Updated 2009-October
Papers (795) that quote: Pascual-Marqui RD, Michel CM, Lehmann D: Low resolution electromagnetic tomography: a new method for localizing electrical activity in the brain. International Journal of Psychophysiology 1994; 18: 49-65.

Summary: The regulation of the timing of sleep is thought to be linked to the temporal dynamics of slow-wave activity [SWA, electroencephalogram (EEG) spectral power in the ∼0.75-4.5 Hz range] in the cortical non-rapid eye movement (NREM) sleep EEG. In the two-process model of sleep regulation, SWA was used as a direct indication of sleep debt, or Process S. Originally, estimation of the latter was performed in a gross way, by measuring average SWA across NREM-REM sleep cycles, fitting an exponential curve to the values thus obtained and estimating its time constant. In later studies, SWA was assumed to be proportional to the instantaneous decay rate of Process S, rather than taken as a direct reflection of S. Following up on this, we extended the existing model of SWA dynamics in which the effects of intrusions of REM sleep and wakefulness were incorporated. For each subject, a 'gain constant' can be estimated that quantifies the efficiency of SWA in dissipating S. As the course of SWA is variable across cortical locations, local differences are likely to exist in the rate of discharge of S, eventually leading to different levels of S in different cortical regions. In this study, we estimate the extent of local differences of SWA regulation on the basis of the extended model of SWA dynamics, for 26 locations on the scalp. We observed higher efficiency of SWA in dissipation of S in frontal EEG derivations, suggesting that SWA regulation has a clear local aspect. This result further suggests that the process involved in (local) SWA regulation cannot be identical to the Process S involved (with Process C) in effectual determination of sleep timing - a single behaviour that cannot vary between locations on the scalp. We therefore propose to distinguish these two representations and characterize the former, purely SWA-related, as 'Process Z', which then is different for different locations on the scalp. To demonstrate those differences, we compare the gain constants derived for the medial EEG derivations (Fz, Cz, Pz, Oz) with each other and with the decay rate derived from SWA values per NREM-REM sleep cycle. © 2008 European Sleep Research Society.

2. Zariffa, J. and M.R. Popovic, Localization of active pathways in peripheral nerves: A simulation study. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2009. 17(1): p. 53-62.

Summary: A methodology is investigated for determining the location of active pathways in a peripheral nerve using measurements from a multicontact cuff electrode. The problem is treated as an inverse problem of source localization and solved using the sLORETA algorithm, developed for the electroencephalogram/ magnetoencephalogram source localization problem. Simulated measurements are generated corresponding to action potentials traveling along either one or three pathways in a rat sciatic nerve. The performance of the proposed methodology using these measurements is evaluated in terms of localization error, missed pathways, and spurious pathways. The source localization performance when assuming an idealized nerve anatomy is compared to that when the correct anatomy is known. The effect of a spatio-temporal constraint based on the nerve anatomy and electrophysiology is also investigated. The approach in its present form was not found to be sufficiently reliable for subfascicular localization in practice, due to mean localization errors in the 140-180 μm range, high numbers of spurious pathways, and low resolution. Nonetheless, the constraints were shown to produce a marked reduction in the number of spurious pathways. Conditions under which the source localization approach may be useful for peripheral nerves are discussed. © 2006 IEEE.

3. Zaehle, T., L. Jancke, C.S. Herrmann, and M. Meyer, Pre-attentive spectro-temporal feature processing in the human auditory system. Brain Topography, 2009. 22(2): p. 97-108.

Summary: In the present study, we investigated the pre-attentive processing of low-level acoustic properties and the impact of this mechanism on functional lateralization in the human auditory system. Mismatch negativity (MMN) of the event-related potentials (ERP) were recorded in 19 adult humans who passively listened to a standard stimulus and spectrally and temporally deviant sounds. We predicted modulations of the MMN amplitude in response to spectrally and temporally graded deviants. Based on recent models of functional hemispheric lateralisation, we further hypothesized a left-lateralized source of the MMN in response to temporal deviants and, in contrast, a right-lateralized source of the MMN in response to spectral deviants. In agreement with our hypothesis, we showed that spectrally and temporally deviant sounds lead to robust MMNs recorded from frontocentral scalp electrodes. The amplitudes of the MMNs were modulated by the grade of spectral and temporal deviation from the standard sound. Furthermore, by using an assumption-free source localization approach (LORETA) we demonstrated functionally lateralized activations with dominance of the right hemisphere for the processing of spectral characteristics and of the left hemisphere for the processing of temporal acoustic properties. Results of our study further contribute to the ongoing debate on the role of low-level acoustic feature perception in functional hemispheric lateralization in the context of auditory and speech processing. Our data indicate that the pre-attentive feature-specific deviant processing is mediated by partly distinct neural subsystems for temporal and spectral information. © 2009 Springer Science+Business Media, LLC.

4. Yao, J., A. Chen, C. Carmona, and J.P.A. Dewald, Cortical overlap of joint representations contributes to the loss of independent joint control following stroke. NeuroImage, 2009. 45(2): p. 490-499.

Summary: The loss of independent joint control in the paretic upper limb is a cardinal sign of movement disorders following stroke. However, the underlying neural mechanisms for such a loss following stroke are still largely unknown. In order to investigate the possible contribution of altered sensorimotor cortical activity to the loss of independent joint control, we measured electroencephalographic (EEG) and torque signals during the generation of static shoulder/elbow torques. We found significant increases in the overlap of shoulder and elbow joint representations at the cortical level in stroke subjects as compared to control subjects. Linear regression results demonstrated significant associations between the cortical overlap of joint representations and the degree of the loss of independent joint control. Therefore, we conclude that an increased overlap of cortical representations for shoulder and elbow contributes to the expression of the loss of independent shoulder/elbow control of the paretic upper limb in chronic hemiparetic stroke survivors. © 2008 Elsevier Inc. All rights reserved.

5. Weis, M., F. Römer, M. Haardt, D. Jannek, and P. Husar, Multi-dimensional space-time-frequency component analysis of event related EEG data using closed-form PARAFAC. ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, 2009: p. 349-352.

Summary: The efficient analysis of electroencephalographic (EEG) data is a long standing problem in neuroscience, which has regained new interest due to the possibilities of multidimensional signal processing. We analyze event related multi-channel EEG recordings on the basis of the time-varying spectrum for each channel. It is a common approach to use wavelet transformations for the time-frequency analysis (TFA) of the data. To identify the signal components we decompose the data into time-frequency-space atoms using Parallel Factor (PARAFAC) analysis. In this paper we show that a TFA based on the Wigner-Ville distribution together with the recently developed closedform PARAFAC algorithm enhance the separability of the signal components. This renders it an attractive approach for processing EEG data. Additionally, we introduce the new concept of component amplitudes, which resolve the scaling ambiguity in the PARAFAC model and can be used to judge the relevance of the individual components. ©2009 IEEE.

6. Van Overwalle, F., S. Van den Eede, K. Baetens, and M. Vandekerckhove, Trait inferences in goal-directed behavior: ERP timing and localization under spontaneous and intentional processing. Social Cognitive and Affective Neuroscience, 2009. 4(2): p. 177-190.

Summary: This study measured event-related potentials (ERPs) during multiple goal and trait inferences, under spontaneous or intentional instructions. Participants read sentences describing several goal-implying behaviors of a target person from which also a strong trait could be inferred or not. The last word of each sentence determined the consistency with the inference induced during preceding sentences. In comparison with behaviors that implied only a goal, stronger waveforms beginning at ∼150 ms were obtained when the behaviors additionally implied a trait. These ERPs showed considerable parallels between spontaneous and intentional inferences. This suggests that traits embedded in a stream of goal-directed behaviors were detected more rapidly and automatically than mere goals, irrespective of the participants' spontaneous or intentional instructions. In line with this, source localization (LORETA) of the ERPs show predominantly activation in the temporo-parietal junction (TPJ) during 150-200 ms, suggesting that goals were detected at that time interval. During 200-300 ms, activation was stronger at the medial prefrontal cortex (mPFC) for multiple goals and traits as opposed to goals only, suggesting that traits were inferred during this time window. A cued recall measure taken after the presentation of the stimulus material support the occurrence of goal and trait inferences and shows significant correlations with the neural components, indicating that these components are valid neural indices of spontaneous and intentional social inferences. The early detection of multiple goal and trait inferences is explained in terms of their greater social relevance, leading to privileged attention allocation and processing in the brain. © The Author (2009). Published by Oxford University Press.

7. Van der Cruyssen, L., M. Van Duynslaeger, A. Cortoos, and F. Van Overwalle, ERP time course and brain areas of spontaneous and intentional goal inferences. Social Neuroscience, 2009. 4(2): p. 165-184.

Summary: This study measured event-related potentials during spontaneous and intentional goal inferences. Participants read sentences describing the behavior of a target person from which a strong goal or intention could be inferred. The last word of each sentence determined the consistency with the goal induced during preceding sentences. In comparison with behaviors that were consistent with the implied goal, a stronger P200 waveform was obtained when the behaviors were irrelevant with that goal or did not contain goal-directed behavior at all, and this P200 showed considerable parallels between spontaneous and intentional inferences. This indicates that goals were inferred rapidly and automatically while reading the behaviors, irrespective of the participants' spontaneous or intentional instructions. In line with this, source localization (LORETA) of the event-related potentials shows predominantly activation in the temporoparietal junction (TPJ) during and immediately after goal detection (225-300 ms). Before and after this time interval, however, activation is stronger at the TPJ during spontaneous processing, and stronger at the medial prefrontal cortex (mPFC) during intentional processing. Memory measures taken after the presentation of the stimulus materials support the occurrence of goal inferences and show significant correlations with the neural components, indicating that these components are valid neural indices of spontaneous and intentional goal inferences. The results are highly similar to previous ERP research on trait inferences that revealed a similar division of brain activation for spontaneous (TPJ) and intentional (mPFC) processes, but appearing later at about 600 ms, pointing to similar brain areas recruited for social inferences, but at different timings for different inference types.

8. Valdés-Sosa, P.A., M. Vega-Hernández, J.M. Sánchez-Bornot, E. Martínez-Montes, and M.A. Bobes, EEG source imaging with spatio-temporal tomographic nonnegative independent component analysis. Human Brain Mapping, 2009. 30(6): p. 1898-1910.

Summary: This article describes a spatio-temporal EEG/MEG source imaging (ESI) that extracts a parsimonious set of "atoms" or components, each the outer product of both a spatial and a temporal signature. The sources estimated are localized as smooth, minimally overlapping patches of cortical activation that are obtained by constraining spatial signatures to be nonnegative (NN), orthogonal, sparse, and smooth-in effect integrating ESI with NN-ICA. This constitutes a generalization of work by this group on the use of multiple penalties for ESI. A multiplicative update algorithm is derived being stable, fast and converging within seconds near the optimal solution. This procedure, spatio-temporal tomographic NN ICA (STTONNICA), is equally able to recover superficial or deep sources without additional weighting constraints as tested with simulations. STTONNICA analysis of ERPs to familiar and unfamiliar faces yields an occipital-fusiform atom activated by all faces and a more frontal atom that only is active with familiar faces. The temporal signatures are at present unconstrained but can be required to be smooth, complex, or following a multivariate autoregressive model. © 2009 Wiley-Liss, Inc.

9. Toth, M., B. Faludi, J. Wackermann, J. Czopf, and I. Kondakor, Characteristic changes in brain electrical activity due to chronic hypoxia in patients with obstructive sleep apnea syndrome (OSAS): A combined EEG study using LORETA and omega complexity. Brain Topography, 2009. 22(3): p. 185-190.

Summary: EEG background activity of patients with obstructive sleep apnea syndrome (OSAS, N = 25) was compared to that of normal controls (N = 14) to reflect alterations of brain electrical activity caused by chronic intermittent hypoxia in OSAS. Global and regional (left vs. right, anterior vs. posterior) measures of spatial complexity (Omega) were used to characterize the degree of spatial synchrony of EEG. Low resolution electromagnetic tomography (LORETA) was used to localize generators of EEG activity in separate frequency bands. Comparing patients to controls, lower Omega complexity was found globally and in the right hemisphere. Using LORETA, an increased medium frequency activity was seen bilaterally in the precuneus, paracentral and posterior cingulate cortex. These findings indicate that alterations caused by chronic hypoxia in brain electrical activity in regions associated with influencing emotional regulation, long-term memory and the default mode network. Global synchronization (lower Omega complexity) may indicate a significantly reduced number of relatively independent, parallel neural processes due to chronic global hypoxic state in apneic patients as well as over the right hemisphere. © 2009 Springer Science+Business Media, LLC.

10. Tombini, M., F. Zappasodi, L. Zollo, G. Pellegrino, G. Cavallo, F. Tecchio, E. Guglielmelli, and P.M. Rossini, Brain activity preceding a 2D manual catching task. NeuroImage, 2009. 47(4): p. 1735-1746.

Summary: We investigated the event-related desynchronization (ERD) and synchronization (ERS) properties of cortical EEG rhythms in regions of interest (ROI) during the preparation of a 2D task for manual catching of a moving object. EEG signals were recorded through a 32-channel system in eleven healthy subjects during the interception task consisting of 2D catching with the right hand of a handle moving at constant velocity (1.5 m/s) on a predefined straight trajectory. The first session of catching movements (CATCHING_PRE) was compared with a second session after 1 h with identical characteristics (CATCHING_POST) and with other two conditions, where the subjects had to reach and grasp the handle fixed in the medium of platform (REACHING) and they looked at the object moving without catching it (GAZE TRACKING). Changes of cortical rhythms were correlated with dynamic and kinematic indexes of motor performance in both catching sessions. Movements requiring different strategies (predictive versus prospective) are supported by specific changes of cortical EEG rhythms: in the CATCHING condition a more evident power decrease (ERD) in alpha 2 and beta band in the sensorimotor region contralateral to the catching hand was observed, while in the REACHING one a bilateral ERD in beta band was found. Motor learning and movement automatization were characterized by a significant reduction of theta ERS in the anterior cingulate cortex (ACC), a ROI linked to focused attention, and with a shift of neuronal activation in alpha 2 band from the bilateral superior parietal areas to the homologous area of the left hemisphere. Finally, our EEG findings are consistent with the role of supplementary motor (SMA), premotor and prefrontal areas in motor planning and preparation. In particular, theta ERS in left SMA significantly correlated with an improvement of motor performance, as evidenced by its correlation with the training-related reduction of interception time (IT). © 2009 Elsevier Inc. All rights reserved.

11. Tereshchenko, E.P., V.A. Ponomarev, Y.D. Kropotov, and A. Müller, Comparative efficiencies of different methods for removing blink artifacts in analyzing quantitative electroencephalogram and event-related potentials. Human Physiology, 2009. 35(2): p. 241-247.

Summary: Different methods for blink artifact correction in multichannel electoencephalogram (EEG) have been compared with respect to their efficiency and the relative systemic error of the estimation of the parameters of EEG spectra and event-related potentials (ERPs). Three methods of blink artifact correction have been used: Distraction of the electrooculogram (EOG) signals from EEG signals, zeroing independent EEG components associated with vertical eye movement, and zeroing the principal EEG components related to blinking. The results have shown that these correction methods can substantially improve the accuracy of the estimation of quantitative EEG parameters while only slightly distorting signals from most EEG sites. It is concluded that wide use of these methods for EEG processing in fundamental and applied studies would be advisable. © Pleiades Publishing, Ltd. 2009.

12. Tei, S., P.L. Faber, D. Lehmann, T. Tsujiuchi, H. Kumano, R.D. Pascual-Marqui, L.R.R. Gianotti, and K. Kochi, Meditators and non-meditators: EEG source imaging during resting. Brain Topography, 2009. 22(3): p. 158-165.

Summary: Many meditation exercises aim at increased awareness of ongoing experiences through sustained attention and at detachment, i.e., non-engaging observation of these ongoing experiences by the intent not to analyze, judge or expect anything. Long-term meditation practice is believed to generalize the ability of increased awareness and greater detachment into everyday life. We hypothesized that neuroplasticity effects of meditation (correlates of increased awareness and detachment) would be detectable in a no-task resting state. EEG recorded during resting was compared between Qigong meditators and controls. Using LORETA (low resolution electromagnetic tomography) to compute the intracerebral source locations, differences in brain activations between groups were found in the inhibitory delta EEG frequency band. In the meditators, appraisal systems were inhibited, while brain areas involved in the detection and integration of internal and external sensory information showed increased activation. This suggests that neuroplasticity effects of long-term meditation practice, subjectively described as increased awareness and greater detachment, are carried over into non-meditating states. © 2009 Springer Science+Business Media, LLC.

13. Tamaki, M., T. Matsuoka, H. Nittono, and T. Hori, Activation of fast sleep spindles at the premotor cortex and parietal areas contributes to motor learning: A study using sLORETA. Clinical Neurophysiology, 2009. 120(5): p. 878-886.

Summary: Objective: The present study examined whether slow and/or fast sleep spindles are related to visuomotor learning, by examining the densities of current sleep spindle activities. Methods: Participants completed a visuomotor task before and after sleep on the learning night. This task was not performed on the non-learning night. Standard polysomnographic recordings were made. After the amplitudes of slow and fast spindles were calculated, sLORETA was used to localize the source of slow and fast spindles and to investigate the relationship between spindle activity and motor learning. Results: Fast spindle amplitude was significantly larger on the learning than on the non-learning nights, particularly at the left frontal area. sLORETA revealed that fast spindle activities in the left frontal and left parietal areas were enhanced when a new visuomotor skill was learned. There were no significant learning-dependent changes in slow spindle activity. Conclusions: Fast spindle activity increases in cortical areas that are involved in learning a new visuomotor skill. The thalamocortical network that underlies the generation of fast spindles may contribute to the synaptic plasticity that occurs during sleep. Significance: Activity of fast sleep spindles is a possible biomarker of memory deficits. © 2009 International Federation of Clinical Neurophysiology.

14. Stern, Y., M.Y. Neufeld, S. Kipervasser, A. Zilberstein, I. Fried, M. Teicher, and E. Adi-Japha, Source localization of temporal lobe epilepsy using PCA - LORETA analysis on ictal EEG recordings. Journal of Clinical Neurophysiology, 2009. 26(2): p. 109-116.

Summary: Localizing the source of an epileptic seizure using noninvasive EEG suffers from inaccuracies produced by other generators not related to the epileptic source. The authors isolated the ictal epileptic activity, and applied a source localization algorithm to identify its estimated location. Ten ictal EEG scalp recordings from five different patients were analyzed. The patients were known to have temporal lobe epilepsy with a single epileptic focus that had a concordant MRI lesion. The patients had become seizure-free following partial temporal lobectomy. A midinterval (∼5 seconds) period of ictal activity was used for Principal Component Analysis starting at ictal onset. The level of epileptic activity at each electrode (i.e., the eigenvector of the component that manifest epileptic characteristic), was used as an input for low-resolution tomography analysis for EEG inverse solution (). The algorithm accurately and robustly identified the epileptic focus in these patients. Principal component analysis and source localization methods can be used in the future to monitor the progression of an epileptic seizure and its expansion to other areas. Copyright © 2009 American Clinical Neurophysiology Society.

15. Soei, E., C. Bellebaum, and I. Daum, Relational and non-relational memory - Electrophysiological correlates of novelty detection, repetition detection and subsequent memory. European Journal of Neuroscience, 2009. 29(2): p. 388-398.

Summary: The dissociability of novelty detection in relational (RM) and non-relational memory (NRM) is currently under debate. To further address the time courses and underlying brain correlates of novelty detection, event-related potentials (ERPs) were analysed for encoding and retrieval on three memory tasks in healthy subjects. Spatial and non-spatial RM as well as NRM were assessed separately. The ERPs related to RM and NRM were dissociable for hits and correct rejections in an early and late time window. An early old/new effect was observed for NRM. A late old/new effect replicated the frequently reported recollection-associated old/new effect in terms of direction and amplitudes. Four different novelty types (spatial relational, non-spatial relational, horizontal non-relational and inverted non-relational) were examined. The P3a related to novelty detection differed in horizontal vs. inverted distractors in NRM, but not in spatial vs. non-spatial RM. ERPs for repetition detection (hits during retrieval) and also for subsequent hits (encoding phase) differed between RM and NRM. These findings are discussed in relation to potential brain correlates in RM and NRM during encoding and retrieval. © 2008 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

16. Shulman, A., B. Goldstein, and A.M. Strashun, Final common pathway for tinnitus: Theoretical and clinical implications of neuroanatomical substrates. International Tinnitus Journal, 2009. 15(1): p. 5-50.

Summary: A final common pathway (FCP) for tinnitus has been hypothesized since 1989 for all clinical types of tinnitus, particularly subjective idiopathic tinnitus (SIT) of the severe disabling type. This was intended to explain the transformation-transition of the sensation of an aberrant auditory sensation - tinnitus (i.e., the sensory component) - to one of affect (i.e., the emotional-behavioral component) or, conversely, that an emotional-behavioral stimulus (affect) can result in the clinical manifestation of a sensation (a sensory stimulus). Understanding the pathophysiology of this transformation is fundamental for the diagnosis of tinnitus and the treatment of the patient, and it presents a dilemma to basic science, neuroscience, and clinical medicine. Clinically, tinnitus is not a unitary symptom; it constitutes many clinical types; can have its origin in the auditory or nonauditory systems and in the peripheral or central nervous system; and may be clinically manifest or subclinical. Accumulating evidence is presented to support the original hypothesis of an FCP. The resolution of this dilemma involves sensory processing (i.e., the integration, identification, and understanding of the ongoing, underlying, simultaneous, multiple associated brain function processes not only from one sensory modality but from multiple sensory modalities accompanying and associated with an FCP). In the FCP, the predominant brain function process is that of the sensory-affect transformation of a sensation and its conscious awareness by the affected patient. The neuroanatomical substrates identified in 1989 in tinnitus patients (reported originally in 1991 and published in 1995) are presented as a common framework for the hypothesis of an FCP. They further the understanding of the clinical heterogeneity of the tinnitus symptom, clinically manifest as multiple brain functions associated with the clinical course of tinnitus patients, particularly those with SIT. The FCP provides a model for tinnitus theory, diagnosis, and treatment. The FCP is not a tinnitus theory. Specifically, it is a hypothesis that attempts to explain how an aberrant auditory sensory stimulus becomes transformed into one of affect and somatomotor response. The neuroanatomical substrates of the FCP provide a basis for the identification of the involved neurocircuitries and neurochemistries. The physiology and biochemistry underlying the neuroanatomical substrates of the FCP provide a basis for translation for tinnitus diagnosis and treatment. The neuroanatomical substrates of the FCP are presented as algorithms of (1) components of a sensation (i.e., sensory, affect, and psychomotor), a translation from basic sensory physiology for tinnitus; (2) clinically manifest biophysiological brain functions and underlying processes associated with the tinnitus; (3) a model for investigation of metabolic-electrophysiological correlates for tinnitus; (4) the basis for an integrated theory of tinnitus and brain function (i.e., tinnitus dyssynchrony-synchrony theory; (5) a model for the identification of underlying neurocircuitries and neurochemistries involved in brain for the sensory-affect transformation of an aberrant auditory stimulus (tinnitus); (6) a model for the selection-introduction of innovative therapies attempting tinnitus relief; and (7) its clinical translation for objective monitoring systems for the determination of the efficacy of modalities of therapy attempting tinnitus relief. The hypothesis of the FCP for tinnitus and the identified neuroanatomical substrates, when viewed in terms of the physiology of sensory processing, is considered to be expanded and broader in its application for all sensations, normal or aberrant.

17. Schendan, H.E. and S.M. Maher, Object knowledge during entry-level categorization is activated and modified by implicit memory after 200 ms. NeuroImage, 2009. 44(4): p. 1423-1438.

Summary: The timing of activating memory about visual objects is important for theories of human cognition but largely unknown, especially for tasks like entry level categorization that activate semantic memory. We tested an implicit memory-categorization "equivalence" hypothesis of multiple memory systems theory that a cortical system that stores structural knowledge to support entry level categorization also stores long-term, perceptual implicit memory, resulting in priming of this knowledge. Event-related brain potentials (ERPs) were recorded to impoverished pictures of new and repeated objects that were similar in perceptual properties but differed in categorization success. The cortical dynamics of object knowledge were defined using categorization ratings and naming. As predicted, rating, naming, and repetition effects on a frontocentral N350 show that implicit memory modifies the object knowledge network supporting categorization. This ERP is a complex of components between 200 and 500 ms indexing temporally overlapping substates from more perceptual to more conceptual knowledge. A frontopolar N350 subcomponent defines the first substate of a process of object model selection from occipitotemporal cortex based on shape similarity, and indicates that implicit memory in this system is greater with better categorization success. Afterwards, parietal positivity and a slow wave index secondary, post-model selection processes, like evaluating the success of a decision or memory match, and working memory for overt report, respectively. Altogether, ERP findings support the equivalence hypothesis and a two-state interactive account of visual object knowledge, and delineate the timing of multiple memory systems. © 2008 Elsevier Inc. All rights reserved.

18. Saletu, M., P. Anderer, G.M. Saletu-Zyhlarz, M. Mandl, B. Saletu, and J. Zeitlhofer, Modafinil improves information processing speed and increases energetic resources for orientation of attention in narcoleptics: Double-blind, placebo-controlled ERP studies with low-resolution brain electromagnetic tomography (LORETA). Sleep Medicine, 2009. 10(8): p. 850-858.

Summary: Background and purpose: Recent neuroimaging studies in narcolepsy discovered significant gray matter loss in the right prefrontal and frontomesial cortex, a critical region for executive processing. In the present study, event-related potential (ERP) low-resolution brain electromagnetic tomography (LORETA) was used to investigate cognition before and after modafinil as compared with placebo. Patients and methods: In a double-blind, placebo-controlled cross-over design, 15 patients were treated with a 3-week fixed titration scheme of modafinil and placebo. The Epworth Sleepiness Scale (ESS), Maintenance of Wakefulness Test (MWT) and auditory ERPs (odd-ball paradigm) were obtained before and after the 3 weeks of therapy. Latencies, amplitudes and LORETA sources were determined for standard (N1 and P2) and target (N2 and P300) ERP components. Results: The ESS score improved significantly from 15.4 (± 4.0) under placebo to 10.2 (± 4.1) under 400 mg modafinil (p = 0.004). In the MWT, latency to sleep increased nonsignificantly after modafinil treatment (11.9 ± 6.9 versus 13.3 ± 7.1 min). In the ERP, N2 and P300 latencies were shortened significantly. While ERP amplitudes showed only minor changes, LORETA revealed increased source strengths: for N1 in the left auditory cortex and for P300 in the medial and right dorsolateral prefrontal cortex. Conclusion: LORETA revealed that modafinil improved information processing speed and increased energetic resources in prefrontal cortical regions, which is in agreement with other neuroimaging studies. © 2009 Elsevier B.V. All rights reserved.

19. Saletu, B., P. Anderer, M. Wolzt, D. Nosiska, A. Assandri, E. Noseda, F. Nannipieri, and G.M. Saletu-Zyhlarz, Double-blind, placebo-controlled, multiple-ascending-dose study on the pharmacodynamics of ABIO-08/01, a new CNS drug with potential anxiolytic activity: 2. EEG-tomography findings based on LORETA (low-resolution brain electromagnetic tomography). Neuropsychobiology, 2009. 59(2): p. 110-122.

Summary: Effects of ABIO-08/01, a new potentially anxiolytic isoxazoline, on regional electrical brain generators were investigated by 3-dimensional EEG tomography. In a double- blind, placebo-controlled, multiple-ascending-dose study, 16 healthy males (30.2 ± 5.7 years) received 3 oral drug doses (10, 20, 40 mg) and placebo for 7 days (8-day wash-out) in a randomized non-balanced design for phase-1 studies. A 3-min vigilance-controlled (V) EEG, a 4-min resting (R) EEG with eyes closed, a 1-min eyes-open (EO) EEG and psychometric tests were performed 0, 1 and 6 h after taking the drug on days 1 and 5. Low-resolution brain electromagnetic tomography (LORETA) was computed from the spectrally analyzed EEG data, and differences between drug and placebo were displayed as statistical parametric maps. Data were registered to the Talairach-Tournoux Human Brain Atlas available as a digitized MRI. An overall omnibus significance test followed by a voxel-by-voxel t test demonstrated significant regional EEG changes after ABIO-08/01 versus placebo, dependent on recording condition, dose and time. While in the EO-EEG specifically the lowest dose of ABIO-08/01 induced pronounced sedative effects (delta/theta and beta increase) 1 h after acute and slightly less so after superimposed administration, in the 6th hour a decrease in alpha and beta activity signaled less sedative and more relaxant action. In the V-EEG these changes were less pronounced, in the R-EEG partly opposite. Hemisphere-specific changes were observed, suggesting increases in LORETA power over the left temporal, parietal, superior frontal regions and decreases over the right prefrontal, temporal pole and occipital regions. These LORETA changes are discussed in the light of neuroimaging findings on anxiety and anxiolytics. Copyright © 2009 S. Karger AG, Basel.

20. Romero, S., M.A. Mañanas, and M.J. Barbanoj, Influence of ocular filtering in eeg data on the assessment of drug-induced effects on the brain, in Human Brain Mapping. 2009. p. 1470-1480.

21. Ricardo-Garcell, J., J.J. González-Olvera, E. Miranda, T. Harmony, E. Reyes, L. Almeida, L. Galán, D. Díaz, L. Ramírez, A. Fernández-Bouzas, and E. Aubert, EEG sources in a group of patients with major depressive disorders. International Journal of Psychophysiology, 2009. 71(1): p. 70-74.

Summary: EEG sources were assessed in a group of patients with major moderate-severe depressive disorder (MDD) as classified by trained clinicians according to DSM-IV criteria. Frequency Domain Variable Resolution Electromagnetic Tomography (FD-VARETA) was used to calculate EEG sources. The Z-values indicated that EEG sources were abnormal (increase in current density) in all patients, with most demonstrating abnormal EEG sources in both hemispheres but with maximal inverse solution located primarily in the right. Twenty-nine patients had a predominant topography of the abnormal EEG maximal inverse solution in the frontal lobes. The remaining seven patients had a bilateral abnormal increase in current density in the superior parietal lobe. The EEG maximal abnormal inverse solution frequency was observed in both hemispheres such that the increases in current density were prevalent in alpha and theta bands. The results suggest that any of the two hemispheres could be affected by MDD, but abnormal EEG sources can be found more frequently in the right one, with the maximal abnormal inverse solution at the alpha and theta bands in frontal and parietal cortices. © 2008 Elsevier B.V. All rights reserved.

22. Ribolsi, M., G. Koch, V. Magni, G. Di Lorenzo, I.A. Rubino, A. Siracusano, and D. Centonze, Abnormal brain lateralization and connectivity in schizophrenia. Reviews in the Neurosciences, 2009. 20(1): p. 61-70.

Summary: Schizophrenia is a complex disorder mainly characterized by thought disturbances, hallucinations, and decay of social and cognitive performances. From past attempts to identify the exclusive brain lesions responsible for specific domains of schizophrenia symptoms such as delusion and auditory hallucinations, recent data pointed towards network alterations leading to abnormal brain asymmetry and connectivity as important determinants of schizophrenia pathophysiology. Several contributions have reported reduced brain lateralization in schizophrenia, causing a failure of left hemisphere dominance. Evidence of altered connectivity among distinct cortical areas is also accumulating. The aim of the present article is to critically review such contributions.

23. Ren, G.Q., Y. Yang, and X. Li, Early cortical processing of linguistic pitch patterns as revealed by the mismatch negativity. Neuroscience, 2009. 162(1): p. 87-95.

Summary: Previous brain imaging studies have shown the left hemispheric dominance for processing of lexical tone in native speakers. However, the low temporal resolution related to neuroimaging techniques might not explicitly detect the brain activities that occur at a relatively small or a determined time frame. We used the mismatch negativity (MMN) and a source estimation technique (low-resolution electromagnetic tomography [LORETA]) to probe the brain activities underlying the early pre-attentive processing of Mandarin lexical tone and intonation. A passive oddball paradigm was applied to present tone and intonation contrast in a speech and nonspeech context. The results showed that no difference of the MMN amplitudes existed between speech and nonspeech conditions, although a larger MMN was found for tone than intonation condition. Source localization of the MMNs for all of the conditions showed the right hemispheric dominance, regardless of their linguistic functions (tone vs. intonation) or speech context (speech vs. nonspeech). Interestingly, the MMN generator for normal tone and hummed tone originated from the same cortical area (right parietal lobe, BA 19). These findings suggest that the pre-attentive cortical processing can be modulated not only by speech stimuli, but also by their nonspeech hums. Our data are compatible with the acoustic hypothesis of speech processing. Crown Copyright © 2009.

24. Proverbio, A.M., M. Del Zotto, N. Crotti, and A. Zani, A no-go related prefrontal negativity larger to irrelevant stimuli that are difficult to suppress. Behavioral and Brain Functions, 2009. 5.

Summary: Background: There is a wide debate in the literature about whether N2/P3 effects in no-go trials reflect the inhibition of an intended action, or the absence of a negative movement-related potential typical of go trials. The aim of this study was to provide an objective measure of the suppression of irrelevant information (in a conjoined selective visual attention task) under conditions that were perfectly comparable from the viewpoint of the motoric processes involved. Methods: Twenty-nine right-handed students took part in the study. Their EEGs were recorded from 128 scalp sites while they viewed gratings of four different spatial frequencies (from 0.75 to 6 c/deg) randomly flashed in the four upper and lower quadrants of the visual field. The tasks consisted of attending and responding to a conjunction of spatial frequency and space location. Intermediate frequencies (1.5 and 3 c/deg) acted as distracters or lures. Analysis of the ERPs elicited by the same physical stimulus, close in spatial frequency to the actual target and falling within the attended quadrant (pseudo-target) vs. a non-target location, allowed us to identify the time course and neural bases of brain activation during the suppression of irrelevant information. Results: FAs were on average 9% for pseudo-targets and 0.2% for other types of lures, indicating that the former were more difficult to suppress. Target-related ERP components (occipito/temporal selection negativity, posterior P3b and precentral motor N2) were greater to pseudo-targets than other distracters. A large prefrontal negativity (370-430 ms) was also identified, much larger to pseudo-targets than non-targets (and absent in response to real targets), thus reflecting response inhibition and top-down cognitive control processes. Conclusion: A LORETA inverse solution identified the neural generators of this effect in the left dorsolateral prefrontal cortex (DLPF), left and right fusiform gyri and bilateral superior temporal cortices. The tentative hypothesis is advanced that these activations might reflect the modulatory effects exerted by the fronto/temporal circuit for the suppression of irrelevant information. © 2009 Proverbio et al; licensee BioMed Central Ltd.

25. Proverbio, A.M., R. Adorni, A. Zani, and L. Trestianu, Sex differences in the brain response to affective scenes with or without humans. Neuropsychologia, 2009. 47(12): p. 2374-2388.

Summary: Recent findings have demonstrated that women might be more reactive than men to viewing painful stimuli (vicarious response to pain), and therefore more empathic [Han, S., Fan, Y., & Mao, L. (2008). Gender difference in empathy for pain: An electrophysiological investigation. Brain Research, 1196, 85-93]. We investigated whether the two sexes differed in their cerebral responses to affective pictures portraying humans in different positive or negative contexts compared to natural or urban scenarios. 440 IAPS slides were presented to 24 Italian students (12 women and 12 men). Half the pictures displayed humans while the remaining scenes lacked visible persons. ERPs were recorded from 128 electrodes and swLORETA (standardized weighted Low-Resolution Electromagnetic Tomography) source reconstruction was performed. Occipital P115 was greater in response to persons than to scenes and was affected by the emotional valence of the human pictures. This suggests that processing of biologically relevant stimuli is prioritized. Orbitofrontal N2 was greater in response to positive than negative human pictures in women but not in men, and not to scenes. A late positivity (LP) to suffering humans far exceeded the response to negative scenes in women but not in men. In both sexes, the contrast suffering-minus-happy humans revealed a difference in the activation of the occipito/temporal, right occipital (BA19), bilateral parahippocampal, left dorsal prefrontal cortex (DPFC) and left amygdala. However, increased right amygdala and right frontal area activities were observed only in women. The humans-minus-scenes contrast revealed a difference in the activation of the middle occipital gyrus (MOG) in men, and of the left inferior parietal (BA40), left superior temporal gyrus (STG, BA38) and right cingulate (BA31) in women (270-290 ms). These data indicate a sex-related difference in the brain response to humans, possibly supporting human empathy. © 2008.

26. Proverbio, A. and R. Adorni, New insights into name category-related effects: Is the Age of Acquisition a possible factor? Behavioral and Brain Functions, 2009. 5.

Summary: Background: Electrophysiological, hemodynamic and neuropsychological studies have provided evidence of dissociation in the way words belonging to different semantic categories (e.g., animals, tools, actions) are represented in the brain. The aim of the present study was to investigate whether a word's semantic domain may affect the amplitude and latency of ERP components, independently of any other factor. Methods: EEGs were recorded from 16 volunteers engaged in a lexical decision task (word/non-word discrimination) involving 100 words (flora and fauna names). This task allowed us to evaluate differences in processing between words belonging to different categories (fauna vs. flora) independently of task demands. All stimuli were balanced in terms of length, frequency of occurrence, familiarity and imageability. Low Resolution Electromagnetic Tomography (LORETA) was performed on ERP difference waves of interest. Results: Our findings showed that the two categories were discriminated as early as 200 ms post-stimulus, with larger responses to flora names over the left occipito-temporal areas, namely BA37 and BA20. Category-related ERP differences were also observed in the amplitudes of the later centro-parietal N400, posterior P300 and anterior LP components. Behavioral responses to words denoting fauna were more accurate than to words denoting flora. Conclusion: Overall, it seems that it was easier to access the lexical properties of fauna, probably because of their biologically relevant status. The results are discussed in the light of the possible role played by different factors. © 2009 Adorni and Proverbio; licensee BioMed Central Ltd.

27. Pratt, H., A. Starr, H.J. Michalewski, A. Dimitrijevic, N. Bleich, and N. Mittelman, Auditory-evoked potentials to frequency increase and decrease of high- and low-frequency tones. Clinical Neurophysiology, 2009. 120(2): p. 360-373.

Summary: Objective: To define cortical brain responses to large and small frequency changes (increase and decrease) of high- and low-frequency tones. Methods: Event-Related Potentials (ERPs) were recorded in response to a 10% or a 50% frequency increase from 250 or 4000 Hz tones that were approximately 3 s in duration and presented at 500-ms intervals. Frequency increase was followed after 1 s by a decrease back to base frequency. Frequency changes occurred at least 1 s before or after tone onset or offset, respectively. Subjects were not attending to the stimuli. Latency, amplitude and source current density estimates of ERPs were compared across frequency changes. Results: All frequency changes evoked components P50, N100, and P200. N100 and P200 had double peaks at bilateral and right temporal sites, respectively. These components were followed by a slow negativity (SN). The constituents of N100 were predominantly localized to temporo-parietal auditory areas. The potentials and their intracranial distributions were affected by both base frequency (larger potentials to low frequency) and direction of change (larger potentials to increase than decrease), as well as by change magnitude (larger potentials to larger change). The differences between frequency increase and decrease depended on base frequency (smaller difference to high frequency) and were localized to frontal areas. Conclusions: Brain activity varies according to frequency change direction and magnitude as well as base frequency. Significance: The effects of base frequency and direction of change may reflect brain networks involved in more complex processing such as speech that are differentially sensitive to frequency modulations of high (consonant discrimination) and low (vowels and prosody) frequencies. © 2008 International Federation of Clinical Neurophysiology.

28. Pratt, H., A. Starr, H.J. Michalewski, A. Dimitrijevic, N. Bleich, and N. Mittelman, Cortical evoked potentials to an auditory illusion: Binaural beats. Clinical Neurophysiology, 2009. 120(8): p. 1514-1524.

Summary: Objective: To define brain activity corresponding to an auditory illusion of 3 and 6 Hz binaural beats in 250 Hz or 1000 Hz base frequencies, and compare it to the sound onset response. Methods: Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000 Hz to one ear and 3 or 6 Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3 Hz and 6 Hz, in base frequencies of 250 Hz and 1000 Hz. Tones were 2000 ms in duration and presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. Results: All stimuli evoked tone-onset P50, N100 and P200 components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P50 had significantly different sources than the beats-evoked oscillations; and N100 and P200 sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Conclusions: Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Significance: Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp. © 2009 International Federation of Clinical Neurophysiology.

29. Ou, W., A. Nummenmaa, M. Hämäläinen, and P. Golland, Multimodal functional imaging using fMRI-informed regional EEG/MEG source estimation. Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2009. 5636 LNCS: p. 88-100.

Summary: We propose a novel method, fMRI-Informed Regional Estimation (FIRE), which utilizes information from fMRI in E/MEG source reconstruction. FIRE takes advantage of the spatial alignment between the neural and the vascular activities, while allowing for substantial differences in their dynamics. Furthermore, with the regional approach, FIRE can be efficiently applied to a dense grid of sources. Inspection of our optimization procedure reveals that FIRE is related to the re-weighted minimum-norm algorithms, the difference being that the weights in the proposed approach are computed from both the current estimates and fMRI data. Analysis of both simulated and human fMRI-MEG data shows that FIRE reduces the ambiguities in source localization present in the minimum-norm estimates. Comparisons with several joint fMRI-E/MEG algorithms demonstrate robustness of FIRE in the presence of sources silent to either fMRI or E/MEG measurements. © 2009 Springer Berlin Heidelberg.

30. Ou, W., M.S. Hämäläinen, and P. Golland, A distributed spatio-temporal EEG/MEG inverse solver. NeuroImage, 2009. 44(3): p. 932-946.

Summary: We propose a novel ℓ1ℓ2-norm inverse solver for estimating the sources of EEG/MEG signals. Based on the standard ℓ1-norm inverse solvers, this sparse distributed inverse solver integrates the ℓ1-norm spatial model with a temporal model of the source signals in order to avoid unstable activation patterns and "spiky" reconstructed signals often produced by the currently used sparse solvers. The joint spatio-temporal model leads to a cost function with an ℓ1ℓ2-norm regularizer whose minimization can be reduced to a convex second-order cone programming (SOCP) problem and efficiently solved using the interior-point method. The efficient computation of the SOCP problem allows us to implement permutation tests for estimating statistical significance of the inverse solution. Validation with simulated and human MEG data shows that the proposed solver yields source time course estimates qualitatively similar to those obtained through dipole fitting, but without the need to specify the number of dipole sources in advance. Furthermore, the ℓ1ℓ2-norm solver achieves fewer false positives and a better representation of the source locations than the conventional ℓ2 minimum-norm estimates. © 2008 Elsevier Inc. All rights reserved.

31. Ortigue, S., N. Patel, and F. Bianchi-Demicheli, New electroencephalogram (EEG) neuroimaging methods of analyzing brain activity applicable to the study of human sexual response. Journal of Sexual Medicine, 2009. 6(7): p. 1830-1845.

Summary: Introduction. Electroencephalogram (EEG) combined with brain source localization algorithms is becoming a powerful tool in the neuroimaging study of human cerebral functions. Aim. The present article provides a tutorial on the various EEG methods currently used to study the human brain activity, notably during sexual response. Main Outcome Measures. Review of published literature on standard EEG waveform analyses and most recent electrical neuroimaging techniques (microstate approach and two methods of brain source localization). Methods. Retrospective overview of pertinent literature. Results. Although the standard EEG waveform analyses enable millisecond time-resolution information about the human sexual responses in the brain, less is clear about their related spatial information. Nowadays, the improvement of EEG techniques and statistical approaches allows the visualization of the dynamics of the human sexual response with a higher spatiotemporal resolution. Here, we describe these enhanced techniques and summarize along with an overview of what we have learned from them in terms of chronoarchitecture of sexual response in the human brain. Finally, the speculation on how we may be able to use other enhanced approaches, such as independent component analysis, are also presented. Conclusions. EEG neuroimaging has already been proven as a strong worthwhile research tool. Combining this approach with standard EEG waveform analyses in sexual medicine may provide a better understanding of the neural activity underlying the human sexual response in both healthy and clinical populations. Ortigue S, Patel N, and Bianchi-Demicheli F. New EEG neuroimaging methods of analyzing brain activity applicable to the study of human sexual response. © 2009 International Society for Sexual Medicine.

32. Neuhaus, A.H., C. Opgen-Rhein, C. Urbanek, M. Gross, E. Hahn, T.M.T. Ta, S. Koehler, and M. Dettling, Spatiotemporal mapping of sex differences during attentional processing. Human Brain Mapping, 2009. 30(9): p. 2997-3008.

Summary: Functional neuroimaging studies have increasingly aimed at approximating neural substrates of human cognitive sex differences elicited by visuospatial challenge. It has been suggested that females and males use different behaviorally relevant neurocognitive strategies. In females, greater right prefrontal cortex activation has been found in several studies. The spatiotemporal dynamics of neural events associated with these sex differences is still unclear. We studied 22 female and 22 male participants matched for age, education, and nicotine with 29-channel-electroencephalogram recorded under a visual selective attention paradigm, the Attention Network Test. Visual event-related potentials (ERP) were topographically analyzed and neuroelectric sources were estimated. In absence of behavioral differences, ERP analysis revealed a novel frontal-occipital second peak of visual N100 that was significantly increased in females relative to males. Further, in females exclusively, a corresponding central ERP component at around 220 ms was found; here, a strong correlation between stimulus salience and sex difference of the central ERP component amplitude was observed. Subsequent source analysis revealed increased cortical current densities in right rostral prefrontal (BA 10) and occipital cortex (BA 19) in female subjects. This is the first study to report on a tripartite association between sex differences in ERPs, visual stimulus salience, and right prefrontal cortex activation during attentional processing. © 2009 Wiley-Liss, Inc.

33. Murphy, M., B.A. Riedner, R. Huber, M. Massimini, F. Ferrarelli, and G. Tononi, Source modeling sleep slow waves. Proceedings of the National Academy of Sciences of the United States of America, 2009. 106(5): p. 1608-1613.

Summary: Slow waves are the most prominent electroencephalographic (EEG) feature of sleep. These waves arise from the synchronization of slow oscillations in the membrane potentials of millions of neurons. Scalp-level studies have indicated that slow waves are not instantaneous events, but rather they travel across the brain. Previous studies of EEG slow waves were limited by the poor spatial resolution of EEGs and by the difficulty of relating scalp potentials to the activity of the underlying cortex. Here we use high-density EEG (hd-EEG) source modeling to show that individual spontaneous slow waves have distinct cortical origins, propagate uniquely across the cortex, and involve unique subsets of cortical structures. However, when the waves are examined en masse, we find that there are diffuse hot spots of slow wave origins centered on the lateral sulci. Furthermore, slow wave propagation along the anterior-posterior axis of the brain is largely mediated by a cingulate highway. As a group, slow waves are associated with large currents in the medial frontal gyrus, the middle frontal gyrus, the inferior frontal gyrus, the anterior cingulate, the precuneus, and the posterior cingulate. These areas overlap with the major connectional backbone of the cortex and with many parts of the default network. © 2009 by The National Academy of Sciences of the USA.

34. Mueller, E.M., S.G. Hofmann, D.L. Santesso, A.E. Meuret, S. Bitran, and D.A. Pizzagalli, Electrophysiological evidence of attentional biases in social anxiety disorder. Psychological Medicine, 2009. 39(7): p. 1141-1152.

Summary: Background. Previous studies investigating attentional biases in social anxiety disorder (SAD) have yielded mixed results. Recent event-related potential (ERP) studies using the dot-probe paradigm in non-anxious participants have shown that the P1 component is sensitive to visuospatial attention towards emotional faces. We used a dot-probe task in conjunction with high-density ERPs and source localization to investigate attentional biases in SAD. Method. Twelve SAD and 15 control participants performed a modified dot-probe task using angry-neutral and happy-neutral face pairs. The P1 component elicited by face pairs was analyzed to test the hypothesis that SAD participants would display early hypervigilance to threat-related cues. The P1 component to probes replacing angry, happy or neutral faces was used to evaluate whether SAD participants show either sustained hypervigilance or decreased visual processing of threat-related cues at later processing stages. Results. Compared to controls, SAD participants showed relatively (a) potentiated P1 amplitudes and fusiform gyrus (FG) activation to angry-neutral versus happy-neutral face pairs; (b) decreased P1 amplitudes to probes replacing emotional (angry and happy) versus neutral faces; and (c) higher sensitivity (d′) to probes following angry-neutral versus happy-neutral face pairs. SAD participants also showed significantly shorter reaction times (RTs) to probes replacing angry versus happy faces, but no group differences emerged for RT. Conclusions. The results provide electrophysiological support for early hypervigilance to angry faces in SAD with involvement of the FG, and reduced visual processing of emotionally salient locations at later stages of information processing, which might be a manifestation of attentional avoidance. © 2008 Cambridge University Press.

35. Mobascher, A., J. Brinkmeyer, T. Warbrick, F. Musso, H.J. Wittsack, R. Stoermer, A. Saleh, A. Schnitzler, and G. Winterer, Fluctuations in electrodermal activity reveal variations in single trial brain responses to painful laser stimuli - A fMRI/EEG study. NeuroImage, 2009. 44(3): p. 1081-1092.

Summary: Pain is a complex experience with sensory, emotional and cognitive aspects. It also includes a sympathetic response that can be captured by measuring the electrodermal activity (EDA). The present study was performed to investigate which brain areas are associated with sympathetic activation in experimental pain; an issue that has not been addressed with fMRI (functional magnetic resonance imaging) thus far. Twelve healthy subjects received painful laser stimulation to the left hand. The event-related fMRI BOLD (blood oxygen level dependent) response was measured together with simultaneous EEG (electroencephalography) and EDA recordings. Laser stimuli induced the expected EDA response, evoked EEG potentials and BOLD responses. Single trial EDA amplitudes were used to guide further analysis of fMRI and EEG data. We found significantly higher BOLD responses in trials with high EDA vs. low EDA trials, predominantly in the insula and somatosensory cortex (S1/S2). Likewise, in the EEG we found the N2 laser evoked potentials to have significantly higher amplitudes in trials with high vs. low EDA. Furthermore EDA-informed BOLD modeling explained additional signal variance in sensory areas and yielded higher group level activation. We conclude that the sympathetic response to pain is associated with activation in pain-processing brain regions, predominantly in sensory areas and that single trial (EDA)-information can add to BOLD modeling by taking some of the response variability across trials and subjects into account. Thus, EDA is a useful additional, objective index when pain is studied with fMRI/EEG which might be of particular relevance in the context of genetic- and pharmacoimaging. © 2008 Elsevier Inc. All rights reserved.

36. Mobascher, A., J. Brinkmeyer, T. Warbrick, F. Musso, H.J. Wittsack, A. Saleh, A. Schnitzler, and G. Winterer, Laser-evoked potential P2 single-trial amplitudes covary with the fMRI BOLD response in the medial pain system and interconnected subcortical structures. NeuroImage, 2009. 45(3): p. 917-926.

Summary: Pain is a complex experience with sensory, emotional and cognitive aspects. The cortical representation of pain - the pain matrix - consists of a network of regions including the primary (S1) and secondary (S2) sensory cortex, insula, and anterior cingulate cortex (ACC). These structures interact with brain regions such as the prefrontal cortex and the amygdalae. Simultaneous EEG/fMRI (electroencephalography/functional magnetic resonance imaging) has recently been introduced as a method to study the spatiotemporal characteristics of cognitive processes with high spatial and high temporal resolution at the same time. The present study was conducted to clarify if single trial EEG-informed BOLD modeling supports the definition of functional compartments within the pain matrix and interconnected regions. Twenty healthy subjects received painful laser stimulation while EEG and the fMRI blood oxygen level dependent (BOLD) signal were recorded simultaneously. While the laser-evoked N2 potential provided no additional information for BOLD modeling, the regressor obtained from the single trial laser-evoked P2 potential explained additional variance in a network of cortical and subcortical structures that largely overlapped with the pain matrix. This modeling strategy yielded pronounced activation in the ACC, right amygdala and thalamus. Our results suggest that laser-evoked potential (LEP) informed fMRI can be used to visualize BOLD activation in the pain matrix with an emphasis on functional compartments (as defined by the temporal dynamics of the LEP) such as the medial pain system. Furthermore, our findings suggest a concerted effort of the ACC and the amygdala in the cognitive-emotional evaluation of pain. © 2009 Elsevier Inc. All rights reserved.

37. Mitsonis, C.I., C. Potagas, I. Zervas, and K. Sfagos, The effects of stressful life events on the course of multiple sclerosis: A review. International Journal of Neuroscience, 2009. 119(3): p. 315-335.

Summary: There is growing body of evidence that support an association between stressful life events and an increased risk for Multiple Sclerosis (MS) exacerbations. However, the nature of this relationship remains unclear, because of the lack of agreement about the definition of stress and/or because of research design problems. This article summarizes the psychological and biological mechanisms by which stress may impact MS progression. Findings indicate a number of factors, including stressor chronicity, frequency, severity and type, depression, anxiety, health locus of control, optimism, perceived social support, and coping strategies. Applied implications are discussed, concentrating on the need for multidisciplinary care interventions that target patients' disease symptoms. Copyright © 2009 Informa Healthcare USA, Inc.

38. Meltzer, J.A., G.A. Fonzo, and R.T. Constable, Transverse patterning dissociates human EEG theta power and hippocampal BOLD activation. Psychophysiology, 2009. 46(1): p. 153-162.

Summary: Theta oscillations (4-8 Hz) are often modulated in human electroencephalogram (EEG) studies of memory, whereas overlapping frequencies dominate rodent hippocampal EEG. An emerging parallelism between theta reactivity and hippocampal functional magnetic resonance imaging activation has suggested a homology between theta activity in humans and rodents, representing a process of cortico-hippocampal interaction involved in memory. In the present study, we investigated EEG reactivity during performance of a relational memory task that induces a negative hippocampal blood oxygenation level dependent (BOLD) signal change, compared to a nonrelational control condition. Relational trials induced theta increases and alpha decreases. Low Resolution Electromagnetic Brain Tomography estimates localized theta and alpha modulation to frontal midline and parietal midline cortices, respectively, both of which exhibit negative BOLD responses in this task. Thus, theta and alpha dynamics are dissociable from positive BOLD activation, and may, in fact, colocalize with negative BOLD responses. Copyright © 2008 Society for Psychophysiological Research.

39. McMenamin, B.W., A.J. Shackman, J.S. Maxwell, L.L. Greischar, and R.J. Davidson, Validation of regression-based myogenic correction techniques for scalp and source-localized EEG. Psychophysiology, 2009. 46(3): p. 578-592.

Summary: EEG and EEG source-estimation are susceptible to electromyographic artifacts (EMG) generated by the cranial muscles. EMG can mask genuine effects or masquerade as a legitimate effect - even in low frequencies, such as alpha (8-13 Hz). Although regression-based correction has been used previously, only cursory attempts at validation exist, and the utility for source-localized data is unknown. To address this, EEG was recorded from 17 participants while neurogenic and myogenic activity were factorially varied. We assessed the sensitivity and specificity of four regression-based techniques: between-subjects, between-subjects using difference-scores, within-subjects condition-wise, and within-subject epoch-wise on the scalp and in data modeled using the LORETA algorithm. Although within-subject epoch-wise showed superior performance on the scalp, no technique succeeded in the source-space. Aside from validating the novel epoch-wise methods on the scalp, we highlight methods requiring further development. Copyright © 2009 Society for Psychophysiological Research.

40. Maurer, U., K. Bucher, S. Brem, R. Benz, F. Kranz, E. Schulz, S. van der Mark, H.C. Steinhausen, and D. Brandeis, Neurophysiology in Preschool Improves Behavioral Prediction of Reading Ability Throughout Primary School. Biological Psychiatry, 2009. 66(4): p. 341-348.

Summary: Background: More struggling readers could profit from additional help at the beginning of reading acquisition if dyslexia prediction were more successful. Currently, prediction is based only on behavioral assessment of early phonological processing deficits associated with dyslexia, but it might be improved by adding brain-based measures. Methods: In a 5-year longitudinal study of children with (n = 21) and without (n = 23) familial risk for dyslexia, we tested whether neurophysiological measures of automatic phoneme and tone deviance processing obtained in kindergarten would improve prediction of reading over behavioral measures alone. Results: Together, neurophysiological and behavioral measures obtained in kindergarten significantly predicted reading in school. Particularly the late mismatch negativity measure that indicated hemispheric lateralization of automatic phoneme processing improved prediction of reading ability over behavioral measures. It was also the only significant predictor for long-term reading success in fifth grade. Importantly, this result also held for the subgroup of children at familial risk. Conclusions: The results demonstrate that brain-based measures of processing deficits associated with dyslexia improve prediction of reading and thus may be further evaluated to complement clinical practice of dyslexia prediction, especially in targeted populations, such as children with a familial risk. © 2009 Society of Biological Psychiatry.

41. Martín-Loeches, M., A. Sel, P. Casado, L. Jiménez, and L. Castellanos, Encouraging expressions affect the brain and alter visual attention. PLoS ONE, 2009. 4(6).

Summary: Background: Very often, encouraging or discouraging expressions are used in competitive contexts, such as sports practice, aiming at provoking an emotional reaction on the listener and, consequently, an effect on subsequent cognition and/or performance. However, the actual efficiency of these expressions has not been tested scientifically. Methodology/Principal Findings: To fill this gap, we studied the effects of encouraging, discouraging, and neutral expressions on event-related brain electrical activity during a visual selective attention task in which targets were determined by location, shape, and color. Although the expressions preceded the attentional task, both encouraging and discouraging messages elicited a similar long-lasting brain emotional response present during the visuospatial task. In addition, encouraging expressions were able to alter the customary working pattern of the visual attention system for shape selection in the attended location, increasing the P1 and the SP modulations while simultaneously fading away the SN. Conclusions/Significance: This was interpreted as an enhancement of the attentional processes for shape in the attended location after an encouraging expression. It can be stated, therefore, that encouraging expressions, as those used in sport practice, as well as in many other contexts and situations, do seem to be efficient in exerting emotional reactions and measurable effects on cognition. © 2009 Martin-Loeches et al.

42. Mangina, C.A., Historical milestones of Neuroscientific Psychophysiology. International Journal of Psychophysiology, 2009. 73(2): p. 76-80.

Summary: The main developments emphasizing the birth and ascent of Neuroscientific Psychophysiology are highlighted. More than a century ago, monumental contributions laid the grounds for our understanding of the human brain-body-behavior-environment interrelationships with theoretical, methodological, empirical and applied underpinnings. Thousands of Psychophysiologists worldwide have contributed to enrich humanity's knowledge and will continue to enhance Neuroscientific Psychophysiology by enlarging its horizons and important ramifications. The excellence of Neuroscientific Psychophysiology is reflected in the world renowned and highly acclaimed International Journal of Psychophysiology which this year, celebrated its 25th Anniversary. The International Organization of Psychophysiology, associated with the United Nations (New York) unites professional Neuroscientists from around the world and integrates interdisciplinary Psychophysiology as a leading neuroscience. © 2009 Elsevier B.V. All rights reserved.

43. Li, L., D. Yao, and G. Yin, Spatio-temporal dynamics of visual selective attention identified by a common spatial pattern decomposition method. Brain Research, 2009. 1282: p. 84-94.

Summary: Three spatio-temporal neurophysiological patterns involved in visual selective attention were identified from the human event-related potentials (ERPs) by a novel common spatial pattern (CSP) decomposition method and the standardized low resolution brain electromagnetic tomography (sLORETA). In the experiment, stimuli were rapidly presented randomly to the right or left visual fields while subjects attended to one visual field at a time (Clark, Hillyard, 1996. Spatial selective attention affects early extrastriate but not striate components of the visual evoked potential. J. Cogn. Neurosci. 8, 387-402). The spatial patterns indicated that visual cortex, prefrontal cortex (PFC), anterior cingulate cortex (ACC) and posterior parietal cortex (PPC) were involved in the control of top-down attention. The temporal waveforms indicated that contralateral PFC and PPC were activated synchronously at about 150 ms after the stimulus onset, with early attention effects only occurring in PFC, and the PPC was activated earlier than that of PFC during 200-260 ms. The results imply that humans adopt different allocation strategies for resources in visual attention and un-attention situations. For attention case, visual cortex consumes the most resources and for non-attention situation, the ACC and PPC consume the most resources. © 2009 Elsevier B.V. All rights reserved.

44. Levin, R.J., Revisiting post-ejaculation refractory time - What we know and what we do not know in males and in females. Journal of Sexual Medicine, 2009. 6(9): p. 2376-2389.

Summary: Introduction. The post-ejaculation refractory time (PERT), the period after a single ejaculation when further erections and ejaculations are inhibited, has been studied and well-documented in male rats. Since its first attribution in men by Masters and Johnson and its inaccurate delineation in their graphic sexual response model in 1966 it has been infrequently studied whereas scant attention has been paid to any such possible activity in women after female ejaculation. Aim. To critically review our current knowledge about PERT in rats and humans and describe and correct shortcomings and errors in previous publications and propose corrections. Methods. Review of published literature. Main Outcome Measures. Identifying evidence-based data to support authority-based facts. Results. The review exposes the extremely limited evidence-based data that our knowledge of PERT is based on. The paucity of data for most aspects of human PERT is remarkable; even the generally accepted statement that the duration of PERT increases with age has no published support data. Conclusions. Despite numerous studies in rats the mechanisms and site(s) of the activity are poorly understood. Dopaminergic and adrenergic pathways are thought to shorten PERT whereas serotonergic pathways lengthen its duration. Raising the brain serotonin levels in men using SSRIs helps reduce early or premature ejaculation. Rats have an absolute PERT (aPERT) during which erection and ejaculation is inhibited and a relative PERT (rPERT) when a stronger or novel stimulus can, whether such phases exist in men is unexamined. Apart from possible depressed activity in the amygdala and penile dorsal nerve and rejection of prolactin as a major factor in PERT little or no significant advance in understanding human male PERT has occurred. No evidence-based data on women's PERT after female ejaculation exists. New investigations in young and older men utilizing brain imaging and electromagnetic tomography are priority studies to accomplish. © 2009 International Society for Sexual Medicine.

45. Knott, V., A. Millar, and D. Fisher, Sensory gating and source analysis of the auditory P50 in low and high suppressors. NeuroImage, 2009. 44(3): p. 992-1000.

Summary: Impairments in sensory gating in schizophrenia have been reflected by diminished suppression of the scalp-recorded middle latency auditory P50 event-related potential (MLAERP) elicited by the second (S2) of a pair (S1-S2) of clicks. As understanding the functional neural substrates of aberrant gating would have important implications for schizophrenia, this study examined the location and time-course of the neural generators of the P50 MLAERP and its gating on subgroups of healthy volunteers exhibiting low (n = 12) and high (n = 12) P50 suppression. Suppressor differences were observed with S1 P50 (high > low) and S2 P50 (high < low) amplitudes, and current source density analysis with standardized Low Resolution Electromagnetic Tomography (sLORETA) evidenced an S1 P50-related activation of limbic, temporal and parietal regions in the high but not the low suppressors. Distributed source localization of the Gating Difference Wave (GDW), obtained by subtracting the S2 P50 response from the S1 P50 response, also revealed a later and sustained frontal activation to characterize high suppressors. These findings suggest that impaired gating of the kind evident in schizophrenia may involve the deficient functioning of multiple interconnected and temporally overlapping activated brain regions. Crown Copyright © 2008.

46. Khittl, B., H. Bauer, and P. Walla, Change detection related to peripheral facial expression: An electroencephalography study. Journal of Neural Transmission, 2009. 116(1): p. 67-70.

Summary: The objective is to study the change detection of emotion expression by electroencephalography (EEG). A visual letter task was combined with two neutral faces. After a short break another letter task occurred whilst the peripheral faces remained or randomly changed to joy, anger or disgust. Study participants responded whether they had perceived a change in emotion expression or not. Explicit change detection elicited more positive-going EEG amplitudes than change blindness between 750 and 900 ms. A change to disgust elicited largest effects. Furthermore, evidence for implicit change detection occurred. © 2008 Springer-Verlag.

47. Karanasiou, I.S., C. Papageorgiou, E.I. Tsianaka, G.K. Matsopoulos, E.M. Ventouras, and N.K. Uzunoglu, Behavioral and brain pattern differences between acting and observing in an auditory task. Behavioral and Brain Functions, 2009. 5.

Summary: Background: Recent research has shown that errors seem to influence the patterns of brain activity. Additionally current notions support the idea that similar brain mechanisms are activated during acting and observing. The aim of the present study was to examine the patterns of brain activity of actors and observers elicited upon receiving feedback information of the actor's response. Methods: The task used in the present research was an auditory identification task that included both acting and observing settings, ensuring concurrent ERP measurements of both participants. The performance of the participants was investigated in conditions of varying complexity. ERP data were analyzed with regards to the conditions of acting and observing in conjunction to correct and erroneous responses. Results: The obtained results showed that the complexity induced by cue dissimilarity between trials was a demodulating factor leading to poorer performance. The electrophysiological results suggest that feedback information results in different intensities of the ERP patterns of observers and actors depending on whether the actor had made an error or not. The LORETA source localization method yielded significantly larger electrical activity in the supplementary motor area (Brodmann area 6), the posterior cingulate gyrus (Brodmann area 31/23) and the parietal lobe (Precuneus/Brodmann area 7/5). Conclusion: These findings suggest that feedback information has a different effect on the intensities of the ERP patterns of actors and observers depending on whether the actor committed an error. Certain neural systems, including medial frontal area, posterior cingulate gyrus and precuneus may mediate these modulating effects. Further research is needed to elucidate in more detail the neuroanatomical and neuropsychological substrates of these systems. © 2009 Karanasiou et al; licensee BioMed Central Ltd.

48. Kamarajan, C., B. Porjesz, M. Rangaswamy, Y. Tang, D.B. Chorlian, A. Padmanabhapillai, R. Saunders, A.K. Pandey, B.N. Roopesh, N. Manz, A.T. Stimus, and H. Begleiter, Brain signatures of monetary loss and gain: Outcome-related potentials in a single outcome gambling task. Behavioural Brain Research, 2009. 197(1): p. 62-76.

Summary: This study evaluates the event-related potential (ERP) components in a single outcome gambling task that involved monetary losses and gains. The participants were 50 healthy young volunteers (25 males and 25 females). The gambling task involved valence (loss and gain) and amount (50¢ and 10¢) as outcomes. The outcome-related negativity (ORN/N2) and outcome-related positivity (ORP/P3) were analyzed and compared across conditions and gender. Monetary gain (compared to loss) and higher amount (50¢ compared to 10¢) produced higher amplitudes and shorter latencies in both ORN and ORP components. Difference wave plots showed that earlier processing (200-400 ms) is dominated by the valence (loss/gain) while later processing (after 400 ms) is marked by the amount (50¢/10¢). Functional mapping using Low Resolution Electromagnetic Tomography (LORETA) indicated that the ORN separated the loss against gain in both genders, while the ORP activity distinguished the 50¢ against 10¢ in males. This study further strengthens the view that separate brain processes/circuitry may mediate loss and gain. Although there were no gender differences in behavioral and impulsivity scores, ORN and ORP measures for different task conditions had significant correlations with behavioral scores. This gambling paradigm may potentially offer valuable indicators to study outcome processing and impulsivity in normals as well as in clinical populations. © 2008 Elsevier B.V.

49. Joliot, M., G. Leroux, S. Dubal, N. Tzourio-Mazoyer, O. Houdé, B. Mazoyer, and L. Petit, Cognitive inhibition of number/length interference in a Piaget-like task: Evidence by combining ERP and MEG. Clinical Neurophysiology, 2009. 120(8): p. 1501-1513.

Summary: Objective: We combined event-related potential (ERP) and magnetoencephalography (MEG) acquisition and analysis to investigate the electrophysiological markers of the inhibitory processes involved in the number/length interference in a Piaget-like numerical task. Methods: Eleven healthy subjects performed four gradually interfering conditions with the heuristic "length equals number" to be inhibited. Low resolution tomography reconstruction was performed on the combined grand averaged electromagnetic data at the early (N1, P1) and late (P2, N2, P3early and P3late) latencies. Every condition was analyzed at both scalp and regional brain levels. Results: The inhibitory processes were visible on the late components of the electromagnetic brain activity. A right P2-related frontal orbital activation reflected the change of strategy in the inhibitory processes. N2-related SMA/cingulate activation revealed the first occurrence of the stimuli processing to be inhibited. Both P3 components revealed the working memory processes operating in a medial temporal complex and the mental imagery processes subtended by the precuneus. Conclusions: Simultaneous ERP and MEG signal acquisition and analysis allowed to describe the spatiotemporal patterns of neural networks involved in the inhibition of the "length equals number" interference. Significance: Combining ERP and MEG ensured a sensitivity which could be reached previously only through invasive intracortical recordings. © 2009 International Federation of Clinical Neurophysiology.

50. Jaušovec, N. and K. Jaušovec, Do women see things differently than men do? NeuroImage, 2009. 45(1): p. 198-207.

Summary: The aim of the study was to investigate the influence of gender on brain activity. Thirty male and 30 female respondents solved simple auditory and visual tasks while their electroencephalogram (EEG) was recorded. Also recorded was the percentage of oxygen saturation of hemoglobin (%StO2) in the respondents' frontal brain areas with near-infrared spectroscopy (NIRS). The attended task condition was based on the oddball paradigm. Respondents had to mentally count infrequent target stimuli - tones or shapes. In the unattended condition they just listened to tones or viewed different shapes. Gender related differences in EEG activity were only observed in the amplitudes of the early evoked gamma response and the P3 component. Women displayed higher amplitudes than men. A second finding was that these differences were more pronounced for the visual than for the auditory stimuli. No gender related differences were observed in the ERP latencies, as well as in the amplitudes of the P1-N1 complex, and the induced gamma response. The NIRS data showed that males in their frontal brain areas displayed a higher percentage of StO2 than did females; and males also showed a higher increase in %StO2 during task performance as compared with the resting condition. Taken all together the results suggest that the females' visual event-categorization process is more efficient than in males. The data are discussed in the theoretical framework of the evolutionary theory of human spatial sex differences. © 2008 Elsevier Inc. All rights reserved.

51. Ioannides, A.A., Magnetoencephalography (MEG). Methods in Molecular Biology, 2009. 489: p. 167-188.

Summary: Magnetoencephalography (MEG) encompasses a family of non-contact, non-invasive techniques for detecting the magnetic field generated by the electrical activity of the brain, for analyzing this MEG signal and for using the results to study brain function. The overall purpose of MEG is to extract estimates of the spatiotemporal patterns of electrical activity in the brain from the measured magnetic field outside the head. The electrical activity in the brain is a manifestation of collective neuronal activity and, to a large extent, the currency of brain function. The estimates of brain activity derived from MEG can therefore be used to study mechanisms and processes that support normal brain function in humans and help us understand why, when and how they fail. © 2009 Humana Press.

52. Hochman, E.Y., Z. Eviatar, Z. Breznitz, M. Nevat, and S. Shaul, Source localization of error negativity: Additional source for corrected errors. NeuroReport, 2009. 20(13): p. 1144-1148.

Summary: Error processing in corrected and uncorrected errors was studied while participants responded to a target surrounded by flankers. Error-related negativity (ERN/NE) was stronger and appeared earlier in corrected errors than in uncorrected errors. ERN neural sources for each error type were analyzed using low-resolution electromagnetic tomography method of source localization. For corrected errors, the ERN source was located at the anterior cingulate (BA 24) and the medial and superior frontal regions (presupplementary motor area, BA 6), whereas it was located at the anterior cingulate (BA 24) for uncorrected errors. It is suggested that the anterior cingulate is the main source of the ERN with the presupplementary motor area contributing to ERN initiation only if the correct response tendency is sufficiently active to allow for full execution of a correction response. © 2009 Lippincott Williams & Wilkins, Inc.

53. Him, Y.Y., A.Y. Roh, Y. Namgoong, H.J. Jo, J.M. Lee, and J.S. Kwon, Cortical network dynamics during source memory retrieval: Current density imaging with individual MRI. Human Brain Mapping, 2009. 30(1): p. 78-91.

Summary: We investigated the neural correlates of source memory retrieval using low-resolution electromagnetic tomography (LORETA) with 64 channels EEG and individual MRI as a realistic head model. Event-related potentials (ERPs) were recorded while 13 healthy subjects performed the source memory task for the voice of the speaker in spoken words. The source correct condition of old words elicited more positive-going potentials than the correct rejection condition of new words at 400-700 ms post-stimulus and the old/new effects also appeared in the right anterior region between 1,000 and 1,200 ms. We conducted source reconstruction at mean latencies of 311, 604, 793, and 1,100 ms and used statistical parametric mapping for the statistical analysis. The results of source analysis suggest that the activation of the right inferior parietal region may reflect retrieval of source information. The source elicited by the difference ERPs between the source correct and source incorrect conditions exhibited dynamic change of current density activation in the overall cortices with time during source memory retrieval. These results indicate that multiple neural systems may underlie the ability to recollect context. Hum Brain Mapp 30:78-91, 2009. © 2007 Wiley-Liss, inc.

54. Hill, H., An event-related potential evoked by movement planning is modulated by performance and learning in visuomotor control. Experimental Brain Research, 2009. 195(4): p. 519-529.

Summary: Based on a previous exploratory study, the functionality of event-related potentials related to visuomotor processing and learning was investigated. Three pursuit tracking tasks (cursor control either mouse, joystick, or bimanually) revealed the greatest tracking error and greatest learning effect in the bimanual task. The smallest error without learning was found in the mouse task. Error reduction reflected visuomotor learning. In detail, target-cursor distance was reduced continuously, indicating a better fit to a changed direction, whereas response time remained at 300 ms. A central positive ERP component with an activity onset 100 ms after a directional change of the target and most likely generated in premotor areas could be assigned to response planning and execution. The magnitude of this component was modulated by within-and-between- task difficulty and size of the tracking error. Most importantly, the size of this component was sensitive to between-subject performance and increased with visuomotor learning. © 2009 Springer-Verlag.

55. Hennig-Fast, K., N.S. Werner, R. Lermer, K. Latscha, F. Meister, M. Reiser, R.R. Engel, and T. Meindl, After facing traumatic stress: Brain activation, cognition and stress coping in policemen. Journal of Psychiatric Research, 2009. 43(14): p. 1146-1155.

Summary: Introduction: Resilience can be defined as the capacity to recover following stress or trauma exposure by adopting healthy strategies for dealing with trauma and stress. Although the importance of stress resilience has been recognized, the underlying neurocognitive mediators have not yet been identified. Thus, the primary goal of this study was to investigate memory-related brain activity in traumatized policemen who attended a pre-traumatic general stress coping program. Method: Ten traumatized male police officers were compared to demographically matched non-traumatized officers (n = 15) on associative memory by using a block design paradigm. Participants with either another psychiatric comorbidity or neurological disorder were excluded. During functional brain imaging (1.5-Tesla), face-profession pairs had to be encoded twice. For subsequent retrieval the faces were presented as cue stimuli for associating the category of the prior learned profession. Additionally, clinical pattern, stress coping style, and cognitive parameters were assessed. Results: Less BOLD activation was found in the hippocampus, parahippocampal gyrus and fusiform gyrus in the trauma group when compared with the non-trauma group during encoding. This was accompanied by slower reaction times in the trauma group during retrieval. Further impairments were found in context memory and in the use of positive cognitive coping strategies. Discussion: Support was provided for the presence of memory-related disturbances in brain activity associated with trauma even in a resilient population. The contribution of the changes in stress coping ability needs to be further examined in longitudinal studies. © 2009 Elsevier Ltd. All rights reserved.

56. Gurskaya, O.E. and V.A. Ponomaryov, Methods of localization of equivalent EEG sources in the diagnostics of protracted loss of consciousness. Zhurnal Nevrologii i Psihiatrii imeni S.S. Korsakova, 2009. 109(4): p. 36-42.

Summary: Results of EEG study of patients in a protracted unconscious state due to severe cranial trauma using different methods of source localization (independent component analysis, the LORETA method) are presented in order to compare their diagnostic value. Also the results of the study of somatosensory evoked potentials (SSEP) to median nerve stimulation of and EEG are compared. The independent higher frequency components of the EEG power spectrum had the higher activity in the delta-band, were localized predominantly in the frontal brain hemispheres (frontal, temporal regions), positively correlated with pathological neurodynamic SSEP changes (r=0,69; p=0,003) and negatively with the scores on the Glasgow outcome scale (r=-0,66; p=0,005).

57. Galdo-Alvarez, S., M. Lindín, and F. Díaz, Age-related prefrontal over-recruitment in semantic memory retrieval: Evidence from successful face naming and the tip-of-the-tongue state. Biological Psychology, 2009. 82(1): p. 89-96.

Summary: Studies that have attempted to determine the effects of aging on the brain neural sources of memory retrieval have reported two contrasting age effects: under-recruitment and over-recruitment of several prefrontal areas. However, the causes for these effects are still a matter of debate. In order to study the underlying factors that cause the effects, we compared brain activation in young and older adults, in a successful word retrieval condition, and a failed word retrieval condition: the tip-of-the-tongue state. For this, we used the event-related potentials technique and neural source estimation with low-resolution tomographies. The results showed that the older adults did not display under-recruitment in any brain area in comparison with the young adults. However, they displayed additional prefrontal activation that varied depending on the processing stage and the condition, which supports the hypothesis of selective over-recruitment in older adults. © 2009 Elsevier B.V. All rights reserved.

58. Esposito, F., C. Mulert, and R. Goebel, Combined distributed source and single-trial EEG-fMRI modeling: Application to effortful decision making processes. NeuroImage, 2009. 47(1): p. 112-121.

Summary: Single-trial coupling of simultaneously recorded EEG and fMRI time-series can be used to generate fMRI patterns of brain activity with high spatial resolution from EEG responses with high temporal resolution. A forced choice reaction task under different effort conditions has been previously used to demonstrate single-trial EEG-fMRI coupling effects for an early ERP component (N1: 70-150 ms) measured on a single scalp channel (Cz), thereby providing the first multi-modal evidence of early anterior cingulate cortex (ACC) activation in effortful decision making (Mulert, C., Seifert, C., Leicht, G., Kirsch, V., Ertl, M., Karch, S., Moosmann, M., Lutz, J., Möller, H.J., Hegerl, U., Pogarell, O., Jäger, L., 2008. Single-trial coupling of EEG and fMRI reveals the involvement of early anterior cingulate cortex activation in effortful decision making. Neuroimage 42, 158-168.). In this work, we searched for "effort-specific" ERP-N1 sources and explored their single-trial EEG-fMRI correlations for discovering "source-specific" inter-modality coupling effects. To this end, we performed a whole-cortex distributed ERP analysis and used the local source power trial-by-trial variation as an input for single-trial EEG-fMRI coupling analysis. We found a high-effort-specific ERP-N1 source in the ACC and statistically significant differential EEG-fMRI coupling spots in five cortical regions, including the ACC. Our results provide new insights about the neural origins of effort-specific EEG and fMRI response modulations in a choice reaction task and confirm the central role of early ACC activation in motivation-related decision making processes; we discuss the importance of combining distributed source modeling with single-trial coupling for enriching the interpretation of EEG-fMRI patterns. © 2009 Elsevier Inc. All rights reserved.

59. Esposito, F., A. Aragri, T. Piccoli, G. Tedeschi, R. Goebel, and F. Di Salle, Distributed analysis of simultaneous EEG-fMRI time-series: modeling and interpretation issues. Magnetic Resonance Imaging, 2009. 27(8): p. 1120-1130.

Summary: Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) represent brain activity in terms of a reliable anatomical localization and a detailed temporal evolution of neural signals. Simultaneous EEG-fMRI recordings offer the possibility to greatly enrich the significance and the interpretation of the single modality results because the same neural processes are observed from the same brain at the same time. Nonetheless, the different physical nature of the measured signals by the two techniques renders the coupling not always straightforward, especially in cognitive experiments where spatially localized and distributed effects coexist and evolve temporally at different temporal scales. The purpose of this article is to illustrate the combination of simultaneously recorded EEG and fMRI signals exploiting the principles of EEG distributed source modeling. We define a common source space for fMRI and EEG signal projection and gather a conceptually unique framework for the spatial and temporal comparative analysis. We illustrate this framework in a graded-load working-memory simultaneous EEG-fMRI experiment based on the n-back task where sustained load-dependent changes in the blood-oxygenation-level-dependent (BOLD) signals during continuous item memorization co-occur with parametric changes in the EEG theta power induced at each single item. In line with previous studies, we demonstrate on two single-subject cases how the presented approach is capable of colocalizing in midline frontal regions two phenomena simultaneously observed at different temporal scales, such as the sustained negative changes in BOLD activity and the parametric EEG theta synchronization. We discuss the presented approach in relation to modeling and interpretation issues typically arising in simultaneous EEG-fMRI studies. © 2009 Elsevier Inc. All rights reserved.

60. Duru, A.D., A. Ademoglu, and T. Demiralp, Analysis of brain electrical topography by spatio-temporal wavelet decomposition. Mathematical and Computer Modelling, 2009. 49(11-12): p. 2224-2235.

Summary: Currently, the Functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), and Electroencephalography (EEG) recordings are the major techniques of neuroimaging. The EEG with its highest temporal resolution is still a crucial measurement for localization of activities arising from the electrical behaviour of the brain. A scalp topographic map for an EEG may be a superposition of several simpler subtopographic maps, each resulting from an individual electrical source located at a certain depth. Furthermore, this source may have a temporal characteristic as an oscillation or a rhythm that extends in a certain time window which has been a basis of assumption for the time-frequency analysis methods. A method for the spatio-temporal wavelet decomposition of multichannel EEG data is proposed which facilitates the localization of electrical sources separate and/or overlapping on a continuum of time, frequency and space domains. The subtopographic maps asociated with each of these individual components are then used in the MUSIC source localization algorithm. The validations are performed on simulated EEG data. Spatio-temporal wavelet decomposition as a preprocessing method improves the source localization by simplifying the topographic data formed by the superposition of EEG generators, having possible combinations of temporal, frequency and/or spatial overlappings. Spatio-temporal analysis of EEG will help enhance the accuracy of dipole source reconstruction in neuroimaging. © 2008 Elsevier Ltd. All rights reserved.

61. de Munck, J.C. and F. Bijma, Three-way matrix analysis, the MUSIC algorithm and the coupled dipole model. Journal of Neuroscience Methods, 2009. 183(1): p. 63-71.

Summary: The inverse problem of multi-channel MEG/EEG data is considered as a parameter estimation problem. The stability of the solution of the inverse problem, which decreases with the number of included dipoles, can be improved by either adding constraints to the model parameters, or by adding more data of related data sets. The latter approach was taken by Bijma et al. [Bijma F, de Munck JC, Böcker KBE, Huizenga HM, Heethaar RM. The coupled dipole model: an integrated model for multiple MEG/EEG data sets. NeuroImage 2004;23(3):890-904; Bijma F, de Munck JC, Huizenga HM, Heethaar RM, Nehorai A. Simultaneous estimation and testing in multiple MEG data sets. IEEE Trans SP 2005;53(9):3449-60] by introducing coupling matrices that link dipole parameters and source time functions of different data sets. Here, the theoretical foundations of the coupled dipole model are explored and the MUSIC algorithm is generalised to the analysis of multiple related data sets. Similar to the MUSIC algorithm, the number of sources and the number of constraints are derived from the data by considering the minimum possible residual error as a function of the number of sources and constraints. However, contrary to the MUSIC algorithm, where the minimum residual error can be obtained from an SVD analysis of a two-way data matrix, here we deal with multiple data sets and therefore three-way matrix analysis is used. From a simulation study it appears that the number of sources and constraints can be clearly determined from a generalised SVD analysis. The generalisation of the MUSIC algorithm to three-way data gives reasonable estimates of the dipole parameters. These results can be used in the simultaneous analysis of MEG/EEG data of multiple subjects, multiples data sets of the same subject or models where subsequent trials of data show habituation effects. © 2009 Elsevier B.V. All rights reserved.

62. Czigler, I. and L. Pató, Unnoticed regularity violation elicits change-related brain activity. Biological Psychology, 2009. 80(3): p. 339-347.

Summary: Event-related brain electric activity (ERP) was investigated to unnoticed visual changes. The orientation of grid elements (vertical or horizontal) changed after the presentation of 10-15 identical stimuli. The grid patterns were task irrelevant, and were presented in the background of a shape discrimination task. During the first half of the session, participants were unaware of the stimulus change. However, in comparison to the ERPs to the fifth identical stimuli, stimulus change elicited posterior negativities in the 270-375 ms range (visual mismatch negativity, vMMN). With participants instructed on the stimulus change, negativities emerged with earlier onset and with wider distribution. When stimulus change was preceded by only two identical stimuli, there were no such ERP effects. As the results show, a longer sequence of identical unattended stimuli may establish the memory representation of stimulus regularity, and violation of regularity is indicated by posterior negative ERP components (vMMN). © 2008 Elsevier B.V. All rights reserved.

63. Cuspineda Bravo, E.R., C. Machado, T. Virues, E. Martínez-Montes, A. Ojeda, P.A. Valdés, J. Bosch, and L. Valdes, Source analysis of alpha rhythm reactivity using LORETA imaging with 64-channel EEG and individual MRI. Clinical EEG and Neuroscience, 2009. 40(3): p. 150-156.

Summary: Conventional EEG and quantitative EEG visual stimuli (close-open eyes) reactivity analysis have shown their usefulness in clinical practice; however studies at the level of EEG generators are limited. The focus of the study was visual reactivity of cortical resources in healthy subjects and in a stroke patient. The 64 channel EEG and T1 magnetic resonance imaging (MRI) studies were obtained from 32 healthy subjects and a middle cerebral artery stroke patient. Low Resolution Electromagnetic Tomography (LORETA) was used to estimate EEG sources for both close eyes (CE) vs. open eyes (OE) conditions using individual MRI. The t-test was performed between source spectra of the two conditions. Thresholds for statistically significant t values were estimated by the local false discovery rate (lfdr) method. The Z transform was used to quantify the differences in cortical reactivity between the patient and healthy subjects. Closed-open eyes alpha reactivity sources were found mainly in posterior regions (occipito-parietal zones), extended in some cases to anterior and thalamic regions. Significant cortical reactivity sources were found in frequencies different from alpha (lower t-values). Significant changes at EEG reactivity sources were evident in the damaged brain hemisphere. Reactivity changes were also found in the "healthy" hemisphere when compared with the normal population. In conclusion, our study of brain sources of EEG alpha reactivity provides information that is not evident in the usual topographic analysis.

64. Cuetos, F., A. Barbón, M. Urrutia, and A. Domínguez, Determining the time course of lexical frequency and age of acquisition using ERP. Clinical Neurophysiology, 2009. 120(2): p. 285-294.

Summary: Objective: The main goal of the present study was to dissociate the effects on reading of frequency, age of acquisition (AoA) and imageability using the evoked response potential paradigm. Method: Twenty participants read words from three experimental conditions: high and low frequency, late and early age of acquisition and high and low imageability. Results: High frequency words produced more positive mean amplitude than low frequency words in the 175-360 ms post-stimulus onset time window and late AoA produced more negative amplitudes than early AoA in the 400-610 ms window. Imageability did not produce any effect in any time window tested. Brain electromagnetic tomography showed the most activated cortical areas for each category of stimuli. Conclusions: The lexical frequency of words seems to affect an early phase in the recognition process, perhaps at the level of the orthographic input lexicon, while AoA was observed at a later stage, indicating that this variable influence processing at a semantic level or at the links between semantics and phonology. Significance: EEG permits the researcher to investigate the time course, and approximate location in the brain, of psycholinguistic variables. © 2008 International Federation of Clinical Neurophysiology.

65. Corrigan, N.M., T. Richards, S.J. Webb, M. Murias, K. Merkle, N.M. Kleinhans, L.C. Johnson, A. Poliakov, E. Aylward, and G. Dawson, An investigation of the relationship between fmri and erp source localized measurements of brain activity during face processing. Brain Topography, 2009. 22(2): p. 83-96.

Summary: Brain activity patterns during face processing have been extensively explored with functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs). ERP source localization adds a spatial dimension to the ERP time series recordings, which allows for a more direct comparison and integration with fMRI findings. The goals for this study were (1) to compare the spatial descriptions of neuronal activity during face processing obtained with fMRI and ERP source localization using low-resolution electromagnetic tomography (LORETA), and (2) to use the combined information from source localization and fMRI to explore how the temporal sequence of brain activity during face processing is summarized in fMRI activation maps. fMRI and high-density ERP data were acquired in separate sessions for 17 healthy adult males for a face and object processing task. LORETA statistical maps for the comparison of viewing faces and viewing houses were coregistered and compared to fMRI statistical maps for the same conditions. The spatial locations of face processing-sensitive activity measured by fMRI and LORETA were found to overlap in a number of areas including the bilateral fusiform gyri, the right superior, middle and inferior temporal gyri, and the bilateral precuneus. Both the fMRI and LORETA solutions additionally demonstrated activity in regions that did not overlap. fMRI and LORETA statistical maps of face processing-sensitive brain activity were found to converge spatially primarily at LORETA solution latencies that were within 18 ms of the N170 latency. The combination of data from these techniques suggested that electrical brain activity at the latency of the N170 is highly represented in fMRI statistical maps. © 2009 Springer Science+Business Media, LLC.

66. Clemens, B., P. Piros, M. Bessenyei, E. Varga, S. Puskás, and I. Fekete, The electrophysiological "delayed effect" of focal interictal epileptiform discharges. A low resolution electromagnetic tomography (LORETA) study. Epilepsy Research, 2009. 85(2-3): p. 270-278.

Summary: Collating the findings regarding the role of focal interictal epileptiform discharges (IEDs) on CNS functions raises the possibility that IEDs might have negative impact that outlasts the duration of the spike-and-wave complexes. The aim of this study was the electrophysiological demonstration of the "delayed effect" of the IEDs. 19-channel, linked-ears referenced, digital waking EEG records of 11 children (aged 6-14 years, eight with idiopathic, three with cryptogenic focal epilepsy, showing a single spike focus) were retrospectively selected from our database. A minimum of 20 (preferably, 30), 2-s epochs containing a single focal spike-and-wave complex were selected (Spike epochs). Thereafter, Postspike-1 (Ps1), Postspike-2 (Ps2) and Postspike-3 (Ps3) epochs were selected, representing the first and second seconds (Ps1), the third and fourth seconds (Ps2) and the fifth and sixth seconds (Ps3) after the Spike epoch, respectively. Interspike epochs (Is) were selected at a distance at least 10 s after the Spike epoch. Individual analysis: the frequency of interest (FOI = the individual frequency of the wave component of the IEDs), and the region of interest (ROI = the site of the IEDs) were identified by reading the raw EEG waveform and the instant power spectrum. Very narrow band LORETA (low resolution electromagnetic tomography) analysis at the FOI and ROI was carried out. Age-adjusted, Z-transformed LORETA "activity" (=current source density, ampers/meters squared) was compared in the Spike, Ps1, Ps2, Ps3 and Is epochs. Findings: the greatest (uppermost pathological) Z-scores and the greatest spatial extension of the LORETA-abnormality were always found in the Spike epochs, followed by the gradual decrease of activity in terms of severity and spatial extension in the Ps1, Ps2, Ps3 epochs. The lowest (baseline) level and extension of the abnormality was found in the Is epochs. Group analysis: average values of activity across the patients were computed for the temporal decrease of the abnormality. Findings: a clear tendency for the decrease of abnormality was demonstrated. Conclusion: the "delayed effect" of the IEDs was demonstrated electrophysiologically and quantified. The method may be utilized in the individual assessment of the effect of IEDs on cortical activity, the degree and temporo-spatial extension of the abnormality. © 2009 Elsevier B.V. All rights reserved.

67. Ceballos, N.A., L.O. Bauer, and R.J. Houston, Recent EEG and ERP findings in substance abusers. Clinical EEG and Neuroscience, 2009. 40(2): p. 122-128.

Summary: Research on electroencephalographic (EEG) correlates of substance use has a long history. The present paper provides a review of recent studies - 2001 to the present - with a focus on EEG findings in human participants characterized by a history of chronic substance use, abuse or dependence. In some areas (e.g., alcohol and cocaine dependence), the field has attempted to build upon earlier work by incorporating different methodologies or pursuing research questions of a transdisciplinary nature. New areas of inquiry, such as the investigation of EEG differences among users of ecstasy (MDMA) and methamphetamine, have emerged, primarily as a result of an alarming rise in popularity of these drugs.

68. Catena, A., G. Houghton, B. Valdés, and L.J. Fuentes, Unmasking word processing with ERPs: Two novel linear techniques for the estimation of temporally overlapped waveforms. Brain Topography, 2009. 22(1): p. 60-71.

Summary: Masked priming experiments are frequently used to study automatic aspects of word processing. Direct measures of such processing obtained with functional neuroimaging techniques (ERPs, fMRI, etc.) need to isolate the neural activation related to relevant events when they are rapidly followed by others (a situation found in other popular paradigms such as the attentional blink and repetition blindness). Here we examine the assumption of "simple insertion", which underlies the use of subtraction to isolate components of temporally overlapping waveforms. We propose two novel linear methods and illustrate how they extract temporal and spatial ERP components that the subtraction method fails to detect. We show this through the analysis of ERP data from a masked semantic priming procedure. The new techniques reveal activation generated by unconscious (masked) prime words as early as 100 ms and 200 ms post stimulus-onset; a pattern which simple subtraction fails to detect. © 2009 Springer Science+Business Media, LLC.

69. Carbonell, F., K.J. Worsley, N.J. Trujillo-Barreto, and M. Vega-Hernandez, The geometry of time-varying cross-correlation random fields. Computational Statistics and Data Analysis, 2009. 53(9): p. 3291-3304.

Summary: The goal of this paper is to assess the P-value of local maxima of time-varying cross-correlation random fields. The motivation for this comes from an electroencephalography (EEG) experiment, where one seeks connectivity between all pairs of voxels inside the brain at each time point of the recording window. In this way, we extend the results of [Cao, J., Worsley, K.J., 1999b. The geometry of correlation fields with an application to functional connectivity of the brain. The Annals of Applied Probability 9 (4), 1021-1057] by searching for high correlations not only over all pairs of voxels, but over all time points as well. We apply our results to an EEG data set of a face recognition paradigm. Our analysis determines those time instants for which there are significantly correlated regions involved in face recognition. © 2009 Elsevier B.V. All rights reserved.

70. Carbonell, F., K.J. Worsley, and N.J. Trujillo-Barreto, On the Fisher's Z transformation of correlation random fields. Statistics and Probability Letters, 2009. 79(6): p. 780-788.

Summary: One of the most interesting problems studied in Random Field Theory (RFT) is to approximate the distribution of the maximum of a random field. This problem usually appears in a general hypothesis testing framework, where the statistics of interest are the maximum of a random field of a known distribution. In this paper, we use the RFT approach to compare two independent correlation random fields, R1 and R2. Our statistics of interest are the maximum of a random field G, resulting from the difference between the Fisher's Z transformation of R1 and R2, respectively. The Fisher's Z transformation guarantees a Gaussian distribution at each point of G but, unfortunately, G is not transformed into a Gaussian random field. Hence, standard results of RFT for Gaussian random fields are not longer available for G. We show here that the distribution of the maximum of G can still be approximated by the distribution of the maximum of a Gaussian random field, provided there is some correction by its spatial smoothness. Indeed, we present a general setting to obtain this correction. This is done by allowing different smoothness parameters for the components of G. Finally, the performance of our method is illustrated by means of both numerical simulations and real Electroencephalography data, recorded during a face recognition experimental paradigm. © 2008 Elsevier B.V. All rights reserved.

71. Bruni, O., L. Novelli, E. Finotti, A. Luchetti, G. Uggeri, D. Aricò, and R. Ferri, All-night EEG power spectral analysis of the cyclic alternating pattern at different ages. Clinical Neurophysiology, 2009. 120(2): p. 248-256.

Summary: Objective: To analyze in detail the frequency content of the different EEG components of the Cyclic Alternating Pattern (CAP) in the whole sleep of pre-school and school age children compared to normal young adults. Methods: Fourteen pre-school age and 18 school age children and 16 adults were included in this study. Each participant underwent a polysomnographic overnight recording, after an adaptation night; sleep stages and CAP were scored following standard criteria. Average spectra were obtained for each CAP condition from the signal recorded from C3/A2 or C4/A1, separately in sleep stage 2 and slow-wave sleep (SWS), for each subject. Results: The analysis of the relative power density in the three groups showed that in sleep stage 2 and in SWS, CAP A1, A2, A3 subtypes had a significantly higher power in all frequency ranges in pre-school children than in adults, while school children differed mainly for the lower frequencies (<7 Hz). For non-CAP, pre-school and school children differed from adults at almost all frequencies analyzed. Generally, A1, A2 and A3 showed clear spectral differences in the three different groups of subjects with pre-school age children showing slightly less evident differences. Conclusions: CAP subtypes are characterized by clearly different spectra at different ages and also the same subtype shows a different power spectrum, during sleep stage 2 or SWS. This study shows that pre-school children have a different structure of sleep, especially from the microstructural (CAP) point of view: the differences are evident for all the CAP components and for non-CAP in almost all the frequency bands. This finding might be associated to the age-related delta decline in the 0-3 Hz frequency reported in children of the same age. Significance: Our data seem to provide information not available before and useful for the understanding of the impact of CAP on the sleep EEG neurophysiological dynamics at different ages. This type of information is crucial for a more adequate interpretation of data provided by a growing number of studies analyzing CAP in groups of pediatric patients. © 2008 International Federation of Clinical Neurophysiology.

72. Brookings, T., S. Ortigue, S. Grafton, and J. Carlson, Using ICA and realistic BOLD models to obtain joint EEG/fMRI solutions to the problem of source localization. NeuroImage, 2009. 44(2): p. 411-420.

Summary: We develop two techniques to solve for the spatio-temporal neural activity patterns using Electroencephalogram (EEG) and Functional Magnetic Resonance Imaging (fMRI) data. EEG-only source localization is an inherently underconstrained problem, whereas fMRI by itself suffers from poor temporal resolution. Combining the two modalities transforms source localization into an overconstrained problem, and produces a solution with the high temporal resolution of EEG and the high spatial resolution of fMRI. Our first method uses fMRI to regularize the EEG solution, while our second method uses Independent Components Analysis (ICA) and realistic models of Blood Oxygen-Level Dependent (BOLD) signal to relate the EEG and fMRI data. The second method allows us to treat the fMRI and EEG data on equal footing by fitting simultaneously a solution to both data types. Both techniques avoid the need for ad hoc assumptions about the distribution of neural activity, although ultimately the second method provides more accurate inverse solutions. © 2008 Elsevier Inc. All rights reserved.

73. Bolstad, A., B.V. Veen, and R. Nowak, Space-time event sparse penalization for magneto-/electroencephalography. NeuroImage, 2009. 46(4): p. 1066-1081.

Summary: This article presents a new spatio-temporal method for M/EEG source reconstruction based on the assumption that only a small number of events, localized in space and/or time, are responsible for the measured signal. Each space-time event is represented using a basis function expansion which reflects the most relevant (or measurable) features of the signal. This model of neural activity leads naturally to a Bayesian likelihood function which balances the model fit to the data with the complexity of the model, where the complexity is related to the number of included events. A novel Expectation-Maximization algorithm which maximizes the likelihood function is presented. The new method is shown to be effective on several MEG simulations of neurological activity as well as data from a self-paced finger tapping experiment. © 2009 Elsevier Inc. All rights reserved.

74. Bocquillon, P., K. Dujardin, N. Betrouni, V. Phalempin, E. Houdayer, J.L. Bourriez, P. Derambure, and W. Szurhaj, Attention impairment in temporal lobe epilepsy: A neurophysiological approach via analysis of the P300 wave. Human Brain Mapping, 2009. 30(7): p. 2267-2277.

Summary: Purpose: Attention is often impaired in temporal lobe epilepsy (TLE). The P300 wave (an endogenous, event-related potential) is a correlate of attention which is usually recorded during an "oddball paradigm," where the subject is instructed to detect an infrequent target stimulus presented amongst frequent, standard stimuli. Modifications of the P300 wave's latency and amplitude in TLE have been suggested, but it is still not known whether the source regions also differ. Our hypothesis was that temporal lobe dysfunction would modify the P3 source regions in TLE patients. Methods: A comparative, high density, 128-channel electroencephalographic analysis of the characteristics of P300 (P3b latency and amplitude) was performed in 10 TLE patients and 10 healthy controls during auditory and visual oddball paradigms. The P3b sources were localized on individual 3D MR images using the LORETA method and intergroup statistical comparisons were performed using SPM2® software. Results: Our main results (in both individual analyses and intergroup comparisons) revealed a reduction in temporal (and more particularly mesiotemporal) sources and, to a lesser extent, frontal sources in TLE patients, compared with controls. Discussion: This reduction may reflect direct, local cortical dysfunction caused by the epileptic focus or more complex interference between epileptic networks and normal attentional pathways. © 2008 Wiley-Liss, Inc.

75. Barton, M.J., P.A. Robinson, S. Kumar, A. Galka, H.F. Durrant-Whyte, J. Guivant, and T. Ozaki, Evaluating the performance of Kalman-filter-based EEG source localization. IEEE Transactions on Biomedical Engineering, 2009. 56(1): p. 122-136.

Summary: Electroencephalographic (EEG) source localization is an important tool for noninvasive study of brain dynamics, due to its ability to probe neural activity more directly, with better temporal resolution than other imaging modalities. One promising technique for solving the EEG inverse problem is Kalman filtering, because it provides a natural framework for incorporating dynamic EEG generation models in source localization. Here, a recently developed inverse solution is introduced, which uses spatiotemporal Kalman filtering tuned through likelihood maximization. Standard diagnostic tests for objectively evaluating Kalman filter performance are then described and applied to inverse solutions for simulated and clinical EEG data. These tests, employed for the first time in Kalman-filter-based source localization, check the statistical properties of the innovation and validate the use of likelihood maximization for filter tuning. However, this analysis also reveals that the filter's existing space- and time-invariant process model, which contains a single fixed-frequency resonance, is unable to completely model the complex spatiotemporal dynamics of EEG data. This finding indicates that the algorithm could be improved by allowing the process model parameters to vary in space. © 2006 IEEE.

76. Badzakova-Trajkov, G., K.J. Barnett, K.E. Waldie, and I.J. Kirk, An ERP investigation of the Stroop task: The role of the cingulate in attentional allocation and conflict resolution. Brain Research, 2009. 1253(C): p. 139-148.

Summary: The majority of studies support a role of the anterior cingulate cortex (ACC) in the attentional control necessary for conflict resolution in the Stroop task; however, the time course of activation and the neural substrates underlying the Stroop task remain contentious. We used high-density EEG to record visual-evoked potentials from 16 healthy subjects while performing a manual version of the traditional Stroop colour-word task. Difference waveforms for congruent-control and incongruent-control conditions were similar in amplitude and had a similar spatial distribution in the time window of 260-430 ms post stimulus onset. Source estimation indicated particularly middle cingulate involvement in congruent-control and incongruent-control difference waveforms. In contrast, the difference waveform for the incongruent-congruent contrast was observed later (in the time window of 370-480 ms), had a different spatial distribution, and source estimation indicated that the anterior cingulate underlies this difference waveform. As congruent-control and incongruent-control differences have a similar timeframe and cingulate source, we propose that this indicates early attentional allocation processes. That is, the identification of two sources of information (the word and the colour it is printed in) and the selective attention to one. The later peak in the incongruent-congruent difference wave, originating in anterior cingulate, likely reflects identification (and subsequent resolution) of conflict in the two sources of information. © 2008 Elsevier B.V. All rights reserved.

77. Aramaki, M., M. Besson, R. Kronland-Martinet, and S. Ystad, Timbre perception of sounds from impacted materials: Behavioral, electrophysiological and acoustic approaches. Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2009. 5493 LNCS: p. 1-17.

Summary: In this paper, timbre perception of sounds from 3 different impacted materials (Wood, Metal and Glass) was examined using a categorization task. Natural sounds were recorded, analyzed and resynthesized and a sound morphing process was applied to construct sound continua between different materials. Participants were asked to categorize the sounds as Wood, Metal or Glass. Typical sounds for each category were defined on the basis of the behavioral data. The temporal dynamics of the neural processes involved in the categorization task were then examined for typical sounds by measuring the changes in brain electrical activity (Event-Related brain Potentials, ERPs). Analysis of the ERP data revealed that the processing of Metal sounds differed significantly from Glass and Wood sounds as early as 150 ms and up to 700 ms. The association of behavioral, electrophysiological and acoustic data allowed us to investigate material categorization: the importance of damping was confirmed and additionally, the relevancy of spectral content of sounds was discussed. © 2009 Springer Berlin Heidelberg.

78. Adjamian, P., M. Sereda, and D.A. Hall, The mechanisms of tinnitus: Perspectives from human functional neuroimaging. Hearing Research, 2009. 253(1-2): p. 15-31.

Summary: In this review, we highlight the contribution of advances in human neuroimaging to the current understanding of central mechanisms underpinning tinnitus and explain how interpretations of neuroimaging data have been guided by animal models. The primary motivation for studying the neural substrates of tinnitus in humans has been to demonstrate objectively its representation in the central auditory system and to develop a better understanding of its diverse pathophysiology and of the functional interplay between sensory, cognitive and affective systems. The ultimate goal of neuroimaging is to identify subtypes of tinnitus in order to better inform treatment strategies. The three neural mechanisms considered in this review may provide a basis for TI classification. While human neuroimaging evidence strongly implicates the central auditory system and emotional centres in TI, evidence for the precise contribution from the three mechanisms is unclear because the data are somewhat inconsistent. We consider a number of methodological issues limiting the field of human neuroimaging and recommend approaches to overcome potential inconsistency in results arising from poorly matched participants, lack of appropriate controls and low statistical power. © 2009 Elsevier B.V. All rights reserved.

79. Zvyagintsev, M., H. Thönnessen, J. Dammers, F. Boers, and K. Mathiak, An automatic procedure for the analysis of electric and magnetic mismatch negativity based on anatomical brain mapping. Journal of Neuroscience Methods, 2008. 168(2): p. 325-333.

Summary: Data processing techniques in electroencephalography (EEG) and magnetoencephalography (MEG) need user interactions. However, particularly in clinical applications, fast and objective data processing is important. Here we present an observer-independent method for EEG and MEG analysis of mismatch negativity (MMN) that allows reliable estimation of source activity based on objective anatomical references. The procedure integrates several steps including artifact rejection, source estimation and statistical analysis. It enables the evaluation of source activity in a fully automatic and unsupervised manner. To test its feasibility we obtained EEG and MEG responses in an auditory oddball paradigm in 12 healthy volunteers. The automatized method of EEG and MEG data analysis estimated source activity. The automatically detected MMN was closely comparable with the results obtained by a user-controlled method based on the dipole fitting. The presented workflow can be performed easily, rapidly, and reliably. This development may open new fields in research and clinical applications of source-based EEG and MEG. © 2007 Elsevier B.V. All rights reserved.

80. Zouch, W., A. Taleb-Ahmed, A. Ben Hamida, J.L. Bourriez, and P. Derambure, Smooth WMN-FOCUSS method for EEG dipoles localisation. Proceedings of IWSSIP 2008 - 15th International Conference on Systems, Signals and Image Processing, 2008: p. 457-460.

Summary: The new WMN-FOCUSS method is a combination between the Weighted Minimum Norm "WMN" method and the iterative FOCaI Underdetermined System Solver "FOCUSS" one. The initialisation step is very important since it is an iterative method. In this paper, we propose an amelioration of the WMN-FOCUSS by smoothing the current density distribution given by WMN before the initialisation of the iterative process. To reduce the divergence risk, smoothing the first iteration of the WMN-FOCUSS method is also proposed. To evaluate the standard and the smooth WMN-FOCUSS methods, we present a study of the localisation error and the robustness against the noise. The found results show that our method is able to give a good reconstruction of the simulated dipole with small localisation error even with an addition of a white gaussian noise.

81. Zhang, Y., W. van Drongelen, M. Kohrman, and B. He, Three-dimensional brain current source reconstruction from intra-cranial ECoG recordings. NeuroImage, 2008. 42(2): p. 683-695.

Summary: We have investigated 3-dimensional brain current density reconstruction (CDR) from intracranial electrocorticogram (ECoG) recordings by means of finite element method (FEM). The brain electrical sources are modeled by a current density distribution and estimated from the ECoG signals with the aid of a weighted minimum norm estimation algorithm. A series of computer simulations were conducted to evaluate the performance of ECoG-CDR by comparing with the scalp EEG based CDR results. The present computer simulation results indicate that the ECoG-CDR provides enhanced performance in localizing single dipole sources which are located in regions underneath the implanted subdural ECoG grids, and in distinguishing and imaging multiple separate dipole sources, in comparison to the CDR results as obtained from the scalp EEG under the same conditions. We have also demonstrated the applicability of the present ECoG-CDR method to estimate 3-dimensional current density distribution from the subdural ECoG recordings in a human epilepsy patient. Eleven interictal epileptiform spikes (seven from the frontal region and four from parietal region) in an epilepsy patient undergoing surgical evaluation were analyzed. The present promising results indicate the feasibility and applicability of the developed ECoG-CDR method of estimating brain sources from intracranial electrical recordings, with detailed forward modeling using FEM. © 2008 Elsevier Inc. All rights reserved.

82. Zhang, Y., S. Feutl, U. Hauser, C. Richter-Witte, P. Schmorl, H.M. Emrich, and D.E. Dietrich, Clinical correlates of word recognition memory in obsessive-compulsive disorder: An event-related potential study. Psychiatry Research - Neuroimaging, 2008. 162(3): p. 262-272.

Summary: Memory disturbances found in obsessive-compulsive disorder (OCD) may partially be related to dysfunction of cortico-subcortical circuits. However, it is still unknown how OCD symptomatology is related to memory processing. To explore this question, event-related potentials (ERPs) were recorded in a continuous word-recognition paradigm in OCD patients with either severe or moderate scores on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) (group S and group M, n = 8 each) and in normal healthy controls (n = 16). Typically ERPs to repeated items are characterized by more positive waveforms beginning approximately 250 ms post-stimulus. This "old/new effect" has been shown to be relevant for memory processing. The early old/new effect (ca. 300-500 ms) with a frontal distribution is proposed to be a neural correlate of familiarity-based recognition. The late old/new effect (post-500 ms) is assumed to reflect conscious memory retrieval processes. The OCD group S showed a normal early old/new effect and a reduced late old/new effect compared with group M and the control group, but no difference was found between group M and the control group. Source analyses for the late old/new effect showed statistically reduced cerebral activation in the anterior cingulate for OCD group S in contrast to the control group. Additionally, the early old/new effect in OCD group S was negatively correlated with the Y-BOCS total scores, and the late old/new effect was negatively correlated with obsession sub-scores. The severely, not moderately, ill OCD patients showed an impaired conscious recollection of the word-to-be-remembered, which suggested an impairment of working memory capacity in these patients due to a dysfunction in the frontal and cingulate cortex. © 2007 Elsevier Ireland Ltd. All rights reserved.

83. Zariffa, J. and M.R. Popovic, Solution space reduction in the peripheral nerve source localization problem using forward field similarities. Journal of Neural Engineering, 2008. 5(2): p. 191-202.

Summary: Improving our ability to localize bioelectric sources within a peripheral nerve would help us to monitor the control signals flowing to and from any limb or organ. This technology would provide a useful neuroscience tool, and could perhaps be incorporated into a neuroprosthesis interface. We propose to use measurements from a multi-contact nerve cuff to solve an inverse problem of bioelectric source localization within the peripheral nerve. Before the inverse problem can be addressed, the forward problem is solved using finite element modeling. A fine mesh improves the accuracy of the forward problem solution, but increases the number of variables to be solved for in the inverse problem. To alleviate this problem, variables corresponding to mesh elements that are not distinguishable by the measurement setup are grouped together, thus reducing the dimension of the inverse problem without impacting on the forward problem accuracy. A quantitative criterion for element distinguishability is derived using the columns of the leadfield matrix and information about the uncertainty in the measurements. Our results indicate that the number of variables in the inverse problem can be reduced by more than half using the proposed method, without having a detrimental impact on the quality of the localization. © 2008 IOP Publishing Ltd.

84. Yoshioka, T., K. Toyama, M. Kawato, O. Yamashita, S. Nishina, N. Yamagishi, and M.A. Sato, Evaluation of hierarchical Bayesian method through retinotopic brain activities reconstruction from fMRI and MEG signals. NeuroImage, 2008. 42(4): p. 1397-1413.

Summary: A hierarchical Bayesian method estimated current sources from MEG data, incorporating an fMRI constraint as a hierarchical prior whose strength is controlled by hyperparameters. A previous study [Sato, M., Yoshioka, T., Kajihara, S., Toyama, K., Goda, N., Doya, K., Kawato, M., 2004. Hierarchical Bayesian estimation for MEG inverse problem. Neuroimage 23, 806-826] demonstrated that fMRI information improves the localization accuracy for simulated data. The goal of the present study is to confirm the usefulness of the hierarchical Bayesian method by the real MEG and fMRI experiments using visual stimuli with a fan-shaped checkerboard pattern presented in four visual quadrants. The proper range of hyperparameters was systematically analyzed using goodness of estimate measures for the estimated currents. The robustness with respect to false-positive activities in the fMRI information was also evaluated by using noisy priors constructed by adding artificial noises to real fMRI signals. It was shown that with appropriate hyperparameter values, the retinotopic organization and temporal dynamics in the early visual area were reconstructed, which were in a close correspondence with the known brain imaging and electrophysiology of the humans and monkeys. The false-positive effects of the noisy priors were suppressed by using appropriate hyperparameter values. The hierarchical Bayesian method also was capable of reconstructing retinotopic sequential activation in V1 with fine spatiotemporal resolution, from MEG data elicited by sequential stimulation of the four visual quadrants with the fan-shaped checker board pattern at much shorter intervals (150 and 400 ms) than the temporal resolution of fMRI. These results indicate the potential capability for the hierarchical Bayesian method combining MEG with fMRI to improve the spatiotemporal resolution of noninvasive brain activity measurement. © 2008 Elsevier Inc.

85. Yorio, A., A. Tabullo, A. Wainselboim, P. Barttfeld, and E. Segura, Event-related potential correlates of perceptual and functional categories: Comparison between stimuli matching by identity and equivalence, in Neuroscience Letters. 2008. p. 113-118.

86. Xu, P., Y. Tian, X. Lei, X. Hu, and D. Yao, Equivalent charge source model based iterative maximum neighbor weight for sparse EEG source localization. Annals of Biomedical Engineering, 2008. 36(12): p. 2051-2067.

Summary: How to localize the neural electric activities within brain effectively and precisely from the scalp electroencephalogram (EEG) recordings is a critical issue for current study in clinical neurology and cognitive neuroscience. In this paper, based on the charge source model and the iterative re-weighted strategy, proposed is a new maximum neighbor weight based iterative sparse source imaging method, termed as CMOSS (Charge source model based Maximum neighbOr weight Sparse Solution). Different from the weight used in focal underdetermined system solver (FOCUSS) where the weight for each point in the discrete solution space is independently updated in iterations, the new designed weight for each point in each iteration is determined by the source solution of the last iteration at both the point and its neighbors. Using such a new weight, the next iteration may have a bigger chance to rectify the local source location bias existed in the previous iteration solution. The simulation studies with comparison to FOCUSS and LORETA for various source configurations were conducted on a realistic 3-shell head model, and the results confirmed the validation of CMOSS for sparse EEG source localization. Finally, CMOSS was applied to localize sources elicited in a visual stimuli experiment, and the result was consistent with those source areas involved in visual processing reported in previous studies. © 2008 Biomedical Engineering Society.

87. Wu, C., I.J. Kirk, J.P. Hamm, and V.K. Lim, The neural networks involved in pitch labeling of absolute pitch musicians. NeuroReport, 2008. 19(8): p. 851-854.

Summary: Investigating the neural substrates of auditory processing of absolute pitch musicians has relevance for understanding the capabilities of the human brain for plasticity. Electroencephalography was used to examine the N1 of auditory-evoked potentials from absolute pitch musicians, nonabsolute pitch musicians, and nonmusicians during tone labeling tasks with and without presentation of a reference tone. Source localization using low-resolution electromagnetic tomography revealed that when labeling tones without a reference, absolute pitch musicians generated greater activity than nonabsolute pitch musicians in the left and right hemispheres. This suggests that when required to label tones without an external reference, absolute pitch musicians have the ability to recruit a greater network than nonabsolute pitch musicians or nonmusicians. © 2008 Lippincott Williams & Wilkins, Inc.

88. Wan, X., A. Sekiguchi, S. Yokoyama, J. Riera, and R. Kawashima, Electromagnetic source imaging: Backus-Gilbert resolution spread function-constrained and functional MRI-guided spatial filtering. Human Brain Mapping, 2008. 29(6): p. 627-643.

Summary: Electromagnetic source imaging techniques are usually limited by their low spatial resolution, even though these techniques have high temporal resolution. Our heuristic analysis shows that the spatial ambiguity of electromagnetic source localization arises from interference from other sources. In this paper, we suggest a new inverse solution based on the principle of spatial filtering to effectively suppress the interference from other sources, especially from the far sources. By means of this approach, functional MRI information can also be effectively integrated into the inverse solution to further improve spatial accuracy of source localization. Most importantly, the results of source localization by this approach are not significantly biased by incompatible fMRI information. Our simulations and experimental results using electroencephalography based on a realistic head model show that the Backus-Gilbert resolution spread function-constrained and functional MRI-guided spatial filtering suggested in this paper provide high spatial accuracy and resolution of source localization, even in the presence of multiple simultaneously active sources. © 2007 Wiley-Liss, Inc.

89. Walla, P., C. Duregger, K. Greiner, S. Thurner, and K. Ehrenberger, Multiple aspects related to self-awareness and the awareness of others: An electroencephalography study. Journal of Neural Transmission, 2008. 115(7): p. 983-992.

Summary: The effect of possessive pronouns on the encoding of pronoun-noun associations (e.g., my garden) was investigated using the electroencephalography (EEG). Following an alphabetical, semantic and a contextual encoding instruction depth of noun processing was varied within three separate experiments in order to manipulate the grade of awareness related to verbal information processing. Only for the semantic encoding task (lexical decision) response time was significantly longer for nouns associated with the pronoun "mein" (German for "my") than for nouns associated with the pronoun "ein" (German for "a") although pronouns were not to be consciously processed at all. Following recognition tests related to nouns (without their previously associated pronouns) revealed no significant differences related to the number of correctly identified repeated nouns (hits) depending on the kind of previously associated pronoun. The analysis of neurophysiological data revealed a time range between about 250 ms and 400 ms after stimulus onset within which significant pronoun x electrode interactions occurred. No interaction with depth of word processing was found. Overlaid EEG curves, t maps and low resolution brain electromagnetic tomography (LORETA) demonstrate that in this time range "mein" and "sein" associated conditions elicit similar brain activity, both more negative, compared to the "ein" associated condition over occipital electrodes. On the other hand, at left temporal sites the "mein" condition elicited more negative potentials than both other conditions. It is interpreted that EEG recordings reveal two relevant areas, which are sensitive to the concept of a person (as represented by a personal pronoun) between about 250 ms and 400 ms after stimulus onset. One area is located in the occipital region and can distinguish between personal engagement and a neutral condition and the other area is located in the temporal region and is able to distinguish between oneself and somebody else. Together with our previous MEG results (Walla et al. in Neuropsychologia 45:796-809, 2007) we want to combine the inferences in the frame of the "multiple aspects" hypothesis related to research on self-awareness and the awareness of others. © 2008 Springer-Verlag.

90. Ventouras, E.M., P.Y. Ktonas, H. Tsekou, T. Paparrigopoulos, I. Kalatzis, and C.R. Soldatos, Slow and fast EEG sleep spindle component extraction using Independent Component Analysis. 8th IEEE International Conference on BioInformatics and BioEngineering, BIBE 2008, 2008.

Summary: Sleep spindles are groups of rhythmic activity, with a waxing-waning morphology, and are considered a hallmark of stage 2 of the sleep electroencephalogram (EEG). They are present predominantly in stages 2, 3 and 4 of the sleep EEG. Spatial analysis of sleep spindle scalp EEG and EEG inverse problem solutions have provided evidence for the existence of two distinct sleep spindle types, "slow" and "fast" spindles at approximately 12 and 14 Hz, respectively. The present study aimed at processing sleep spindles with Independent Component Analysis (ICA) in order to investigate the possibility of extracting spindle "components" corresponding to separate EEG activity patterns. The EEG activity underlying the components was also investigated, using the Low-Resolution Brain Electromagnetic Tomography (LORETA) technique, inverting the 21-channel EEG recordings to cortical current sources. Results indicate separability and stability of current sources related to sleep spindle "components" reconstructed from separate groups of Independent Components (ICs).

91. Vega-Hernández, M., E. Martínez-Montes, J.M. Sánchez-Bornot, A. Lage-Castellanos, and P.A. Valdés-Sosa, Penalized Least Squares methods for solving the EEG Inverse Problem. Statistica Sinica, 2008. 18(4): p. 1535-1551.

Summary: Most of the known solutions (linear and nonlinear) of the ill-posed EEG Inverse Problem can be interpreted as the estimated coefficients in a penalized regression framework. In this work we present a general formulation of this problem as a Multiple Penalized Least Squares model, which encompasses many of the previously known methods as particular cases (e.g., Minimum Norm, LORETA). New types of inverse solutions arise since recent advances in the field of penalized regression have made it possible to deal with non-convex penalty functions, which provide sparse solutions (Fan and Li (2001)). Moreover, a generalization of this approach allows the use of any combination of penalties based on 11 or 12-norms, leading to solutions with combined properties such as smoothness and sparsity. Synthetic data is used to explore the benefits of non-convex penalty functions (e.g., LASSO, SCAD and LASSO Fusion) and mixtures (e.g., Elastic Net and LASSO Fused) by comparing them with known solutions in terms of localization error, blurring and visibility. Real data is used to show that a mixture model (Elastic Net) allows for tuning the spatial resolution of the solution to range from very concentrated to very blurred sources.

92. van Leeuwen, T., P. Been, M. van Herten, F. Zwarts, B. Maassen, and A. van der Leij, Two-month-old infants at risk for dyslexia do not discriminate /bAk/ from /dAk/: A brain-mapping study. Journal of Neurolinguistics, 2008. 21(4): p. 333-348.

Summary: Dyslexics have problems with categorization of speech sounds, in particular when rapid temporal processing is involved such as in formant transitions of stop-consonants. Infants are already sensitive to such auditory features, but here we show that precursors of impaired categorization are already present in the brain responses of two-month-old infants at familial risk for dyslexia. Natural speech stimuli (/bAk/ and /dAk/), at either side of the phoneme boundary, induced multiple mismatch responses in control infants under pre-attentive and pre-cognitive conditions. Infants at-risk showed an attenuated early mismatch response and an absent late one, in addition to diminished cortical activity in the left hemisphere. These results are consistent with a temporal processing deficit in the infants at risk and may point to an early precursor of the disorder. © 2007.

93. Trujillo-Barreto, N.J., E. Aubert-Vázquez, and W.D. Penny, Bayesian M/EEG source reconstruction with spatio-temporal priors. NeuroImage, 2008. 39(1): p. 318-335.

Summary: This article proposes a Bayesian spatio-temporal model for source reconstruction of M/EEG data. The usual two-level probabilistic model implicit in most distributed source solutions is extended by adding a third level which describes the temporal evolution of neuronal current sources using time-domain General Linear Models (GLMs). These comprise a set of temporal basis functions which are used to describe event-related M/EEG responses. This places M/EEG analysis in a statistical framework that is very similar to that used for PET and fMRI. The experimental design can be coded in a design matrix, effects of interest characterized using contrasts and inferences made using posterior probability maps. Importantly, as is the case for single-subject fMRI analysis, trials are treated as fixed effects and the approach takes into account between-trial variance, allowing valid inferences to be made on single-subject data. The proposed probabilistic model is efficiently inverted by using the Variational Bayes framework under a convenient mean-field approximation (VB-GLM). The new method is tested with biophysically realistic simulated data and the results are compared to those obtained with traditional spatial approaches like the popular Low Resolution Electromagnetic TomogrAphy (LORETA) and minimum variance Beamformer. Finally, the VB-GLM approach is used to analyze an EEG data set from a face processing experiment. © 2007 Elsevier Inc. All rights reserved.

94. Tislerova, B., M. Brunovsky, J. Horacek, T. Novak, M. Kopecek, P. Mohr, and V. Krajca, LORETA functional imaging in antipsychotic-naive and olanzapine-, clozapine- and risperidone-treated patients with schizophrenia. Neuropsychobiology, 2008. 58(1): p. 1-10.

Summary: The aim of our study was to detect changes in the distribution of electrical brain activity in schizophrenic patients who were antipsychotic naive and those who received treatment with clozapine, olanzapine or risperidone. We included 41 subjects with schizophrenia (antipsychotic naive = 11; clozapine = 8; olanzapine = 10; risperidone = 12) and 20 healthy controls. Low-resolution brain electromagnetic tomography was computed from 19-channel electroencephalography for the frequency bands delta, theta, alpha-1, alpha-2, beta-1, beta-2 and beta-3. We compared antipsychotic-naive subjects with healthy controls and medicated patients. (1) Comparing antipsychotic-naive subjects and controls we found a general increase in the slow delta and theta frequencies over the fronto-temporo-occipital cortex, particularly in the temporolimbic structures, an increase in alpha-1 and alpha-2 in the temporal cortex and an increase in beta-1 and beta-2 in the temporo-occipital and posterior limbic structures. (2) Comparing patients who received clozapine and those who were antipsychotic naive, we found an increase in delta and theta frequencies in the anterior cingulate and medial frontal cortex, and a decrease in alpha-1 and beta-2 in the occipital structures. (3) Comparing patients taking olanzapine with those who were antipsychotic naive, there was an increase in theta frequencies in the anterior cingulum, a decrease in alpha-1, beta-2 and beta-3 in the occipital cortex and posterior limbic structures, and a decrease in beta-3 in the frontotemporal cortex and anterior cingulum. (4) In patients taking risperidone, we found no significant changes from those who were antipsychotic naive. Our results in antipsychotic-naive patients are in agreement with existing functional findings. Changes in those taking clozapine and olanzapine versus those who were antipsychotic naive suggest a compensatory mechanism in the neurobiological substrate for schizophrenia. The lack of difference in risperidone patients versus antipsychotic-naive subjects may relate to risperidone's different pharmacodynamic mechanism. Copyright © 2008 S. Karger AG.

95. Tian, Y. and D. Yao, A study on the neural mechanism of inhibition of return by the event-related potential in the Go/Nogo task. Biological Psychology, 2008. 79(2): p. 171-178.

Summary: Inhibition of return (IOR) is a slowed response to a stimulus at recently cued locations when stimulus-onset asynchronies (SOAs) are longer than 250 ms. Using an uninformative peripheral cued Go/Nogo (commit/withdrawal response) task experiment, this study aimed to characterize the neural mechanism of IOR by studying not only the early event-related potentials (ERPs), P1 and N1, but also the late ERPs, Go/Nogo-N2 and P3. Scalp topographies and LORETA showed that the changes in P1 and N1, the cueing effects, were distributed mainly over the dorsal occipito-parietal areas, such as the bilateral middle occipital gyrus and the occipital portion of the cuneus. The changes in the late Nogo-N2 and P3 were distributed mainly over frontal-central areas, such as the right medial frontal gyrus. The Nogo-N2 was smaller and earlier in valid trials than in invalid trials, suggesting that the late component related to IOR was modulated by response preparation inhibition. The Nogo-P3 was larger and later in valid trials than in invalid trials, perhaps indicating that the control system (FEF) was free from an inhibitory marker in the cued locations. These data support a mechanism of IOR consisting of both sensory inhibition and response preparation inhibition. © 2008 Elsevier B.V. All rights reserved.

96. Thompson, T., T. Steffert, T. Ros, J. Leach, and J. Gruzelier, EEG applications for sport and performance. Methods, 2008. 45(4): p. 279-288.

Summary: One approach to understanding processes that underlie skilled performing has been to study electrical brain activity using electroencephalography (EEG). A notorious problem with EEG is that genuine cerebral data is often contaminated by artifacts of non-cerebral origin. Unfortunately, such artifacts tend to be exacerbated when the subject is in motion, meaning that obtaining reliable data during exercise is inherently problematic. These problems may explain the limited number of studies using EEG as a methodological tool in the sports sciences. This paper discusses how empirical studies have generally tackled the problem of movement artifact by adopting alternative paradigms which avoid recording during actual physical exertion. Moreover, the specific challenges that motion presents to obtaining reliable EEG data are discussed along with practical and computational techniques to confront these challenges. Finally, as EEG recording in sports is often underpinned by a desire to optimise performance, a brief review of EEG-biofeedback and peak performance studies is also presented. A knowledge of practical aspects of EEG recording along with the advent of new technology and increasingly sophisticated processing models offer a promising approach to minimising, if perhaps not entirely circumventing, the problem of obtaining reliable EEG data during motion. © 2008 Elsevier Inc. All rights reserved.

97. Taylor, P.C.J., V. Walsh, and M. Eimer, Combining TMS and EEG to study cognitive function and cortico-cortico interactions. Behavioural Brain Research, 2008. 191(2): p. 141-147.

Summary: There has long been an interest in exploring the functional dynamics of the brain's connectivity during cognitive processing, and some recent methodological developments now allow us to test important long-standing hypotheses. This review focuses on the recent development of combined online transcranial magnetic stimulation and electroencephalography (TMS-EEG) and on new studies that have employed this combination to study causal interactions between neural areas involved in perception and cognition. © 2008 Elsevier B.V. All rights reserved.

98. Spyrou, L. and S. Sanei, Source localization of event-related potentials incorporating spatial notch filters. IEEE Transactions on Biomedical Engineering, 2008. 55(9): p. 2232-2239.

Summary: A novel algorithm for the localization of event-related potential (ERP) sources within the brain is proposed here. In this technique, spatial notch filters are developed to exploit the multichannel electroencephalogram data together with a model of ERP with variable parameters in order to accurately localize the corresponding ERP signal sources. The algorithm is robust in the presence of reasonably high noise. The performance of the proposed system has been compared to that of linear constrained minimum variance (LCMV) beamformer for different noise and correlation levels and its superiority has been demonstrated. © 2006 IEEE.

99. Šóš, P., M. Brunovský, J. Horáček, M. Bareš, and M. Kopeček, Utilization of cordance analysis and electromagnetic tomography in monitoring changes of electric brain activity during depressive disorder treatment. Využití kordanční analýzy a elektromagnetické tomografie ke sledování změn elektrické mozkové aktivity během léčby depresivní poruchy, 2008. 12(3): p. 167-171.

Summary: The case report of a depressed patient demonstrates the use of QEEG information in the prediction of a treatment response to an antidepressant and possibly of the maintenance of this response. Resting EEG record of depressive patient, having responded to the new antidepressive treatment (venlafaxine), was analyzed after 1, 4 and 14 weeks using the methods of quantitative electroencephalography (QEEG): cordance analysis and electromagnetic tomography (sLORETA - standardized Low-Resolution Electromagnetic Tomography). Decrease in prefrontal EEG theta cordance was found after the first week of treatment (by the time, when no clinical evidence of improvement was apparent) and the response sustainment correlated with increasing and spreading trend of theta activity (4-8 Hz) current density in dorsal cingulum.

100. Serruya, M.D. and M.J. Kahana, Techniques and devices to restore cognition. Behavioural Brain Research, 2008. 192(2): p. 149-165.

Summary: Executive planning, the ability to direct and sustain attention, language and several types of memory may be compromised by conditions such as stroke, traumatic brain injury, cancer, autism, cerebral palsy and Alzheimer's disease. No medical devices are currently available to help restore these cognitive functions. Recent findings about the neurophysiology of these conditions in humans coupled with progress in engineering devices to treat refractory neurological conditions imply that the time has arrived to consider the design and evaluation of a new class of devices. Like their neuromotor counterparts, neurocognitive prostheses might sense or modulate neural function in a non-invasive manner or by means of implanted electrodes. In order to paint a vision for future device development, it is essential to first review what can be achieved using behavioral and external modulatory techniques. While non-invasive approaches might strengthen a patient's remaining intact cognitive abilities, neurocognitive prosthetics comprised of direct brain-computer interfaces could in theory physically reconstitute and augment the substrate of cognition itself. © 2008 Elsevier B.V. All rights reserved.

101. Seitz, R.J., R. Schäfer, D. Scherfeld, S. Friederichs, K. Popp, H.J. Wittsack, N.P. Azari, and M. Franz, Valuating other people's emotional face expression: a combined functional magnetic resonance imaging and electroencephalography study. Neuroscience, 2008. 152(3): p. 713-722.

Summary: Reading the facial expression of other people is a fundamental skill for social interaction. Human facial expressions of emotions are readily recognized but may also evoke the same experiential emotional state in the observer. We used event-related functional magnetic resonance imaging and multi-channel electroencephalography to determine in 14 right-handed healthy volunteers (29±6 years) which brain structures mediate the perception of such a shared experiential emotional state. Statistical parametric mapping showed that an area in the dorsal medial frontal cortex was specifically activated during the perception of emotions that reflected the seen happy and sad emotional face expressions. This area mapped to the pre-supplementary motor area which plays a central role in control of behavior. Low resolution brain electromagnetic tomography-based analysis of the encephalographic data revealed that the activation was detected 100 ms after face presentation onset lasting until 740 ms. Our observation substantiates recently emerging evidence suggesting that the subjective perception of an experiential emotional state-empathy-is mediated by the involvement of the dorsal medial frontal cortex. © 2008 IBRO.

102. Schulz, E., U. Maurer, S. van der Mark, K. Bucher, S. Brem, E. Martin, and D. Brandeis, Impaired semantic processing during sentence reading in children with dyslexia: Combined fMRI and ERP evidence. NeuroImage, 2008. 41(1): p. 153-168.

Summary: Developmental dyslexia is a specific disorder of reading acquisition characterized by a phonological core deficit. Sentence reading is also impaired in dyslexic readers, but whether semantic processing deficits contribute is unclear. Combining spatially and temporally sensitive neuroimaging techniques to focus on semantic processing can provide a more comprehensive characterization of sentence reading in dyslexia. We recorded brain activity from 52 children (16 with dyslexia, 31 controls) with functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) in two separate counterbalanced sessions. The children silently read and occasionally judged simple sentences with semantically congruous or incongruous endings. fMRI and ERP activation during sentence reading and semantic processing was analyzed across all children and also by comparing children with dyslexia to controls. For sentence reading, we analyzed the response to all words in a sentence; for semantic processing, we contrasted responses to incongruous and congruous endings. Sentence reading was characterized by activation in a left-lateralized language network. Semantic processing was characterized by activation in left-hemispheric regions of the inferior frontal and superior temporal cortex and by an electrophysiological N400 effect after 240 ms with consistent left anterior source localization. Children with dyslexia showed decreased activation for sentence reading in inferior parietal and frontal regions, and for semantic processing in inferior parietal regions, and during the N400 effect. Together, this suggests that semantic impairment during sentence reading reduces dyslexic children's response in left anterior brain regions underlying the more phasic N400 effect and subsequently modulates the more sustained BOLD response in left inferior parietal regions. © 2008 Elsevier Inc. All rights reserved.

103. Santesso, D.L., A.E. Meuret, S.G. Hofmann, E.M. Mueller, K.G. Ratner, E.B. Roesch, and D.A. Pizzagalli, Electrophysiological correlates of spatial orienting towards angry faces: A source localization study. Neuropsychologia, 2008. 46(5): p. 1338-1348.

Summary: The goal of this study was to examine behavioral and electrophysiological correlates of involuntary orienting toward rapidly presented angry faces in non-anxious, healthy adults using a dot-probe task in conjunction with high-density event-related potentials and a distributed source localization technique. Consistent with previous studies, participants showed hypervigilance toward angry faces, as indexed by facilitated response time for validly cued probes following angry faces and an enhanced P1 component. An opposite pattern was found for happy faces suggesting that attention was directed toward the relatively more threatening stimuli within the visual field (neutral faces). Source localization of the P1 effect for angry faces indicated increased activity within the anterior cingulate cortex, possibly reflecting conflict experienced during invalidly cued trials. No modulation of the early C1 component was found for affect or spatial attention. Furthermore, the face-sensitive N170 was not modulated by emotional expression. Results suggest that the earliest modulation of spatial attention by face stimuli is manifested in the P1 component, and provide insights about mechanisms underlying attentional orienting toward cues of threat and social disapproval. © 2007 Elsevier Ltd. All rights reserved.

104. Saletu, M., P. Anderer, G.M. Saletu-Zyhlarz, M. Mandl, J. Zeitlhofer, and B. Saletu, Event-related-potential low-resolution brain electromagnetic tomography (ERP-LORETA) suggests decreased energetic resources for cognitive processing in narcolepsy. Clinical Neurophysiology, 2008. 119(8): p. 1782-1794.

Summary: Objective: Event-related potentials (ERPs) are sensitive measures of both perceptual and cognitive processes. The aim of the present study was to identify brain regions involved in the processes of cognitive dysfunction in narcolepsy by means of ERP tomography. Methods: In 17 drug-free patients with narcolepsy and 17 controls, ERPs were recorded (auditory odd-ball paradigm). Latencies, amplitudes and LORETA sources were determined for standard (N1 and P2) and target (N2 and P300) ERP components. Psychometry included measures of mental performance, affect and critical flicker fusion frequency (CFF). Results: In the ERPs patients demonstrated delayed cognitive N2 and P300 components and reduced amplitudes in midline regions, while N1 and P2 components did not differ from controls. LORETA suggested reduced P300 sources bilaterally in the precuneus, the anterior and posterior cingulate gyri, the ventrolateral prefrontal cortex and the parahippocampal gyrus. In psychometry, patients demonstrated deteriorated mood, increased trait anxiety, decreased CFF and a trend toward reduced general verbal memory and psychomotor activity. Conclusions: Narcoleptic patients showed prolonged information processing, as indexed by N2 and P300 latencies and decreased energetic resources for cognitive processing. Significance: Electrophysiological aberrations in brain areas related to the 'executive attention network' and the 'limbic system' may contribute to a deterioration in mental performance and mood at the behavioral level. © 2008 International Federation of Clinical Neurophysiology.

105. Roach, B.J. and D.H. Mathalon, Event-related EEG time-frequency analysis: An overview of measures and an analysis of early gamma band phase locking in schizophrenia. Schizophrenia Bulletin, 2008. 34(5): p. 907-926.

Summary: An increasing number of schizophrenia studies have been examining electroencephalography (EEG) data using time-frequency analysis, documenting illness-related abnormalities in neuronal oscillations and their synchronization, particularly in the gamma band. In this article, we review common methods of spectral decomposition of EEG, time-frequency analyses, types of measures that separately quantify magnitude and phase information from the EEG, and the influence of parameter choices on the analysis results. We then compare the degree of phase locking (ie, phase-locking factor) of the gamma band (36-50 Hz) response evoked about 50 milliseconds following the presentation of standard tones in 22 healthy controls and 21 medicated patients with schizophrenia. These tones were presented as part of an auditory oddball task performed by subjects while EEG was recorded from their scalps. The results showed prominent gamma band phase locking at frontal electrodes between 20 and 60 milliseconds following tone onset in healthy controls that was significantly reduced in patients with schizophrenia (P =. 03). The finding suggests that the early-evoked gamma band response to auditory stimuli is deficiently synchronized in schizophrenia. We discuss the results in terms of pathophysiological mechanisms compromising event-related gamma phase synchrony in schizophrenia and further attempt to reconcile this finding with prior studies that failed to find this effect. © The Author 2008. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved.

106. Razpurker-Apfeld, I. and H. Pratt, Perceptual visual grouping under inattention: Electrophysiological functional imaging. Brain and Cognition, 2008. 67(2): p. 183-196.

Summary: Two types of perceptual visual grouping, differing in complexity of shape formation, were examined under inattention. Fourteen participants performed a similarity judgment task concerning two successive briefly presented central targets surrounded by task-irrelevant simple and complex grouping patterns. Event-related potentials (ERPs) were recorded from 22 scalp electrodes and source current density estimations were conducted for the net response to the task-irrelevant background patterns, using low-resolution electromagnetic tomography (LORETA). Although participants' subjective reports indicated that neither type of organization induced awareness, electrophysiological results showed they both evoked significant activation in occipital, parieto-temporal and frontal brain areas. Behavioral results demonstrated that only grouping of the simple pattern arose under inattention. In contrast to the complex pattern, the processing of the simple pattern was associated with an initially longer latency and higher activation beginning at 130 ms. These results support the distinction of grouping patterns differing in complexity of shape formation. © 2008 Elsevier Inc. All rights reserved.

107. Putnam, K.M., D.A. Pizzagalli, D.C. Gooding, N.H. Kalin, and R.J. Davidson, Neural activity and diurnal variation of cortisol: Evidence from brain electrical tomography analysis and relevance to anhedonia. Psychophysiology, 2008. 45(6): p. 886-895.

Summary: The medial prefrontal cortex (mPFC), hippocampus, and amygdala are implicated in the regulation of affect and physiological processes, including hypothalamic-pituitary-adrenal (HPA) axis function. Anhedonia is likely associated with dysregulation of these processes. Dense-array resting electroencephalographic and cortisol were obtained from healthy and anhedonic groups. Low-resolution electromagnetic tomography was used to compute intracerebral current density. For the control group, voxelwise analyses found a relationship between current density in beta and gamma bands and steeper cortisol slope (indicative of more adaptive HPA axis functioning) in regions of the hippocampus, parahippocampal gyrus, and mPFC. For the anhedonic group, the mPFC finding was absent. Anhedonia may be characterized by disruptions of mPFC-mediated neuroendocrine regulation, which could constitute a vulnerability to the development of stress-related disorders. Copyright © 2008 Society for Psychophysiological Research.

108. Proverbio, A.M., A. Zani, and R. Adorni, Neural markers of a greater female responsiveness to social stimuli. BMC Neuroscience, 2008. 9.

Summary: Background: There is fMRI evidence that women are neurally predisposed to process infant laughter and crying. Other findings show that women might be more empathic and sensitive than men to emotional facial expressions. However, no gender difference in the brain responses to persons and unanimated scenes has hitherto been demonstrated. Results: Twenty-four men and women viewed 220 images portraying persons or landscapes and ERPs were recorded from 128 sites. In women, but not in men, the N2 component (210-270) was much larger to persons than to scenes. swLORETA showed significant bilateral activation of FG (BA19/37) in both genders when viewing persons as opposed to scenes. Only women showed a source of activity in the STG and in the right MOG (extra-striate body area, EBA), and only men in the left parahippocampal area (PPA). Conclusion: A significant gender difference was found in activation of the left and right STG (BA22) and the cingulate cortex for the subtractive condition women minus men, thus indicating that women might have a greater preference or interest for social stimuli (faces and persons). © 2008 Proverbio et al; licensee BioMed Central Ltd.

109. Proverbio, A.M., A. Zani, and R. Adorni, The left fusiform area is affected by written frequency of words. Neuropsychologia, 2008. 46(9): p. 2292-2299.

Summary: The recent neuroimaging literature gives conflicting evidence about whether the left fusiform gyrus (FG) might recognize words as unitary visual objects. The sensitivity of the left FG to word frequency might provide a neural basis for the orthographic input lexicon theorized by reading models [Patterson, K., Marshall, J. C., & Coltheart, M. (1985). Surface dyslexia: Cognitive and neuropsychological studies of phonological reading. London: Lawrence Erlbaum]. The goal of this study was to investigate the time course and neural correlates of word processing in right-handed readers engaged in an orthographic decision task. Three hundred and twenty Italian words of high and low written frequency and 320 non-derived legal pseudo-words were presented for 250 ms in the central visual field. ERPs were recorded from 128 scalp sites in 10 Italian University students. Behavioural data showed a word superiority effect, with faster RTs to words than pseudo-words. Left occipito/temporal N2 (240 ms) was greater to high-frequency than low-frequency words and pseudo-words. According to the swLORETA inverse solution, the underlying neural source of this effect was located in the left fusiform gyrus of the occipital lobe (X = -29, Y = -66, Z = -10, BA19) and the right superior temporal gyrus (X = 51, Y = 6, Z = -5, BA22), which are probably involved in word recognition and semantic representation, respectively. Later frontal ERP components, LPN (300-350) and P3 (400-500), also showed strong lexical sensitivity, thus suggesting implicit semantic processes. The results shed some light on the possible neural substrate of visual reading disabilities such as developmental surface dyslexia or pure alexia. © 2008 Elsevier Ltd. All rights reserved.

110. Proverbio, A.M. and R. Adorni, Orthographic familiarity, phonological legality and number of orthographic neighbours affect the onset of ERP lexical effects. Behavioral and Brain Functions, 2008. 4.

Summary: Background: It has been suggested that the variability among studies in the onset of lexical effects may be due to a series of methodological differences. In this study we investigated the role of orthographic familiarity, phonological legality and number of orthographic neighbours of words in determining the onset of word/non-word discriminative responses. Methods: ERPs were recorded from 128 sites in 16 Italian University students engaged in a lexical decision task. Stimuli were 100 words, 100 quasi-words (obtained by the replacement of a single letter), 100 pseudo-words (non-derived) and 100 illegal letter strings. All stimuli were balanced for length; words and quasi-words were also balanced for frequency of use, domain of semantic category and imageability. SwLORETA source reconstruction was performed on ERP difference waves of interest. Results: Overall, the data provided evidence that the latency of lexical effects (word/non-word discrimination) varied as a function of the number of a word's orthographic neighbours, being shorter to non-derived than to derived pseudo-words. This suggests some caveats about the use in lexical decision paradigms of quasi-words obtained by transposing or replacing only 1 or 2 letters. Our findings also showed that the left-occipito/temporal area, reflecting the activity of the left fusiform gyrus (BA37) of the temporal lobe, was affected by the visual familiarity of words, thus explaining its lexical sensitivity (word vs. non-word discrimination). The temporo-parietal area was markedly sensitive to phonological legality exhibiting a clear-cut discriminative response between illegal and legal strings as early as 250 ms of latency. Conclusion: The onset of lexical effects in a lexical decision paradigm depends on a series of factors, including orthographic familiarity, degree of global lexical activity, and phonologic legality of non-words. © 2008 Proverbio and Adorni; licensee BioMed Central Ltd.

111. Pratt, H., A. Starr, H.J. Michalewski, N. Bleich, and N. Mittelman, The auditory P50 component to onset and offset of sound. Clinical Neurophysiology, 2008. 119(2): p. 376-387.

Summary: Objective: The auditory Event-Related Potentials (ERP) of component P50 to sound onset and offset have been reported to be similar, but their magnetic homologue has been reported absent to sound offset. We compared the spatio-temporal distribution of cortical activity during P50 to sound onset and offset, without confounds of spectral change. Methods: ERPs were recorded in response to onsets and offsets of silent intervals of 0.5 s (gaps) appearing randomly in otherwise continuous white noise and compared to ERPs to randomly distributed click pairs with half second separation presented in silence. Subjects were awake and distracted from the stimuli by reading a complicated text. Measures of P50 included peak latency and amplitude, as well as source current density estimates to the clicks and sound onsets and offsets. Results: P50 occurred in response to noise onsets and to clicks, while to noise offset it was absent. Latency of P50 was similar to noise onset (56 ms) and to clicks (53 ms). Sources of P50 to noise onsets and clicks included bilateral superior parietal areas. In contrast, noise offsets activated left inferior temporal and occipital areas at the time of P50. Source current density was significantly higher to noise onset than offset in the vicinity of the temporo-parietal junction. Conclusions: P50 to sound offset is absent compared to the distinct P50 to sound onset and to clicks, at different intracranial sources. P50 to stimulus onset and to clicks appears to reflect preattentive arousal by a new sound in the scene. Sound offset does not involve a new sound and hence the absent P50. Significance: Stimulus onset activates distinct early cortical processes that are absent to offset. © 2007 International Federation of Clinical Neurophysiology.

112. Pourtois, G., S. Delplanque, C. Michel, and P. Vuilleumier, Beyond conventional event-related brain potential (ERP): Exploring the time-course of visual emotion processing using topographic and principal component analyses. Brain Topography, 2008. 20(4): p. 265-277.

Summary: Recent technological advances with the scalp EEG methodology allow researchers to record electric fields generated in the human brain using a large number of electrodes or sensors (e.g. 64-256) distributed over the head surface (multi-channel recording). As a consequence, such high-density ERP mapping yields fairly dense ERP data sets that are often hard to analyze comprehensively or to relate straightforwardly to specific cognitive or emotional processes, because of the richness of the recorded signal in both the temporal (millisecond time-resolution) and spatial (multidimensional topographic information) domains. Principal component analyses (PCA) and topographic analyses (combined with distributed source localization algorithms) have been developed and successfully used to deal with this complexity, now offering powerful alternative strategies for data-driven analyses in complement to more traditional ERP analyses based on waveforms and peak measures. In this paper, we first briefly review the basic principles of these approaches, and then describe recent ERP studies that illustrate how they can inform about the precise spatio-temporal dynamic of emotion processing. These studies show that the perception of emotional visual stimuli may produce both quantitative and qualitative changes in the electric field configuration recorded at the scalp level, which are not apparent when using conventional ERP analyses. Additional information gained from these approaches include the identification of a sequence of successive processing stages that may not fully be reflected in ERP waveforms only, and the segregation of multiple or partly overlapping neural events that may be blended within a single ERP waveform. These findings highlight the added value of such alternative analyses when exploring the electrophysiological manifestations of complex and distributed mental functions, as for instance during emotion processing. © 2008 Springer Science+Business Media, LLC.

113. Polezzi, D., L. Lotto, I. Daum, G. Sartori, and R. Rumiati, Predicting outcomes of decisions in the brain. Behavioural Brain Research, 2008. 187(1): p. 116-122.

Summary: When making decisions, the outcomes of different choices play an important role. Feedback is mainly processed in terms of gains and losses. It is as yet unclear whether this distinction holds for predictable as well as unpredictable outcomes. Using ERPs, the present study aimed to determine whether predictable and unpredictable outcomes are coded differently in the brain. Participants had to choose between one of two options: the certain option was always associated with a gain of 10€, while the uncertain option entailed a gain of 30€ or a loss of 10€, with a probability of 50% each. Overall, subjects showed a clear preference for the certain option, a tendency which became more pronounced during the course of the experiment. An early ERP component, the P200, reflected the predictability of outcomes, which was critical for the subsequent decisions. The later feedback related negativity (FRN) reflected the known distinction between gains and losses, while the N500 again reflected differential processing of predictable and unpredictable outcomes. Neither FRN nor the N500 were significantly related to behaviour. Predictability appears to play a central role in outcome evaluation. © 2007 Elsevier B.V. All rights reserved.

114. Polezzi, D., I. Daum, E. Rubaltelli, L. Lotto, C. Civai, G. Sartori, and R. Rumiati, Mentalizing in economic decision-making. Behavioural Brain Research, 2008. 190(2): p. 218-223.

Summary: In the Ultimatum Game, participants typically reject monetary offers they consider unfair even if the alternative is to gain no money at all. In the present study, ERPs were recorded while subjects processed different offers of a proposer. In addition to clearly fair and unfair offers, mid-value offers which cannot be easily classified as fair or unfair and therefore involve more elaborate decision making were analyzed. A fast initial distinction between fair and other kinds of offers was reflected by amplitude of the feedback related negativity (FRN). Mid-value offers were associated with longer RTs, and a larger N350 amplitude. In addition, source analyses revealed a specific involvement of the superior temporal gyrus and the inferior parietal lobule during processing of mid-value offers compared to offers categorized clearly as fair or unfair, suggesting a contribution of mentalizing about the intention of the proposer to the decision making process. Taken together, the present findings support the idea that economic decisions are significantly affected by non-rational factors, trying to narrow the gap between formal theory and the real decisional behaviour. © 2008 Elsevier B.V. All rights reserved.

115. Plummer, C., A.S. Harvey, and M. Cook, EEG source localization in focal epilepsy: Where are we now? Epilepsia, 2008. 49(2): p. 201-218.

Summary: Electroencephalographic source localization (ESL) by noninvasive means is an area of renewed interest in clinical epileptology. This has been driven by innovations in the computer-assisted modeling of dipolar and distributed sources for the investigation of focal epilepsy; a process fueled by the ever-increasing computational power available to researchers for the analysis of scalp EEG recordings. However, demonstration of the validity and clinical utility of these mathematically derived source modeling techniques has struggled to keep pace. This review evaluates the current clinical "fitness" of ESL as applied to the focal epilepsies by examining some of the key studies performed in the field, with emphasis given to clinical work published in the last five years. In doing so, we discuss why ESL techniques have not made an impact on routine epilepsy practice, underlining some of the current problems and controversies in the field. We conclude by examining where ESL currently sits alongside magnetoencephalography and combined EEG-functional magnetic resonance imaging in the investigation of focal epilepsy. © 2008 International League Against Epilepsy.

116. Osterhout, L., A. Poliakov, K. Inoue, J. McLaughlin, G. Valentine, I. Pitkanen, C. Frenck-Mestre, and J. Hirschensohn, Second-language learning and changes in the brain. Journal of Neurolinguistics, 2008. 21(6): p. 509-521.

Summary: Presumably, second-language (L2) learning is mediated by changes in the brain. Little is known about what changes in the brain, how the brain changes, or when these changes occur during learning. Here, we illustrate by way of example how modern brain-based methods can be used to discern some of the changes that occur during L2 learning. Preliminary results from three studies indicate that classroom-based L2 instruction can result in changes in the brain's electrical activity, in the location of this activity within the brain, and in the structure of the learners' brains. These changes can occur during the earliest stages of L2 acquisition. © 2008 Elsevier Ltd. All rights reserved.

117. Olivares-Carreño, E.I. and J. Iglesias-Dorado, Long-latency evoked potentials and mnemonic processing of faces and words. Potenciales evocados de larga latencia y procesamiento mnésico de caras y palabras, 2008. 47(12): p. 624-630.

Summary: Introduction. Evoked potentials are real-time electrophysiological markers of cognitive operations and especially mnemonic processes. The N400 wave has traditionally been studied to characterise the processes involved in memorising verbal material. To investigate the existence of specific memory processes for each information domain, functional analogues of this wave were examined during the processing of non-verbal stimuli, such as faces. Aim. Using an inter-subject design, the classic verbal N400 wave was compared with its functional analogue during the processing of faces in a contextual preactivation task adapted to the visual domain of faces. Subjects and methods. After several sessions dedicated to learning a set of faces, another evoked potential recording session was held in order to analyse the effects of the existence of structural inconsistencies in these stimuli and to compare them, with regard to their topographic distribution and neural generators, with those observed in the classic verbal N400 task. Results. A verbal N400 wave was observed with a (slightly right) centroparietal distribution, and this response was distinguished from another negative wave obtained during the processing of facial inconsistencies in the same group of participants, with a predominantly occipital localisation and differentiated neural generators. Conclusions. These findings support the hypothesis of the specificity of the neural mechanisms involved in the mnemonic processing of faces and words, which is in line with the neurocognitive models that suggest the independence or modularity of memory processes in different domains of information. © 2008, Revista de Neurología.

118. Noirhomme, Q., R.I. Kitney, and B. Macq, Single-trial EEG source reconstruction for brain-computer interface. IEEE Transactions on Biomedical Engineering, 2008. 55(5): p. 1592-1601.

Summary: A new way to improve the classification rate of an EEG-based brain-computer interface (BCI) could be to reconstruct the brain sources of EEG and to apply BCI methods to these derived sources instead of raw measured electrode potentials. EEG source reconstruction methods are based on electrophysiological information that could improve the discrimination between BCI tasks. In this paper, we present an EEG source reconstruction method for BCI. The results are compared with results from raw electrode potentials to enable direct evaluation of the method. Features are based on frequency power change and Bereitschaft potential. The features are ranked with mutual information before being fed to a proximal support vector machine. The dataset IV of the BCI competition II and data from four subjects serve as test data. Results show that the EEG inverse solution improves the classification rate and can lead to results comparable to the best currently known methods. © 2006 IEEE.

119. Nir, R.R., R. Lev, R. Moont, Y. Granovsky, E. Sprecher, and D. Yarnitsky, Neurophysiology of the Cortical Pain Network: Revisiting the Role of S1 in Subjective Pain Perception Via Standardized Low-Resolution Brain Electromagnetic Tomography (sLORETA). Journal of Pain, 2008. 9(11): p. 1058-1069.

Summary: Multiple studies have supported the usefulness of standardized low-resolution brain electromagnetic tomography (sLORETA) in localizing generators of scalp-recorded potentials. The current study implemented sLORETA on pain event-related potentials, primarily aiming at validating this technique for pain research by identifying well-known pain-related regions. Subsequently, we pointed at investigating the still-debated and ambiguous topic of pain intensity coding at these regions, focusing on their relative impact on subjective pain perception. sLORETA revealed significant activations of the bilateral primary somatosensory (SI) and anterior cingulate cortices and of the contralateral operculoinsular and dorsolateral prefrontal (DLPFC) cortices (P < .05 for each). Activity of these regions, excluding DLPFC, correlated with subjective numerical pain scores (P < .05 for each). However, a multivariate regression analysis (R = .80; P = .024) distinguished the contralateral SI as the only region whose activation magnitude significantly predicted the subjective perception of noxious stimuli (P = .020), further substantiated by a reduced regression model (R = .75, P = .008). Based on (1) correspondence of the pain-activated regions identified by sLORETA with the acknowledged imaging-based pain-network and (2) the contralateral SI proving to be the most contributing region in pain intensity coding, we found sLORETA to be an appropriate tool for relevant pain research and further substantiated the role of SI in pain perception. Perspective: Because the literature of pain intensity coding offers inconsistent findings, the current article used a novel tool for revisiting this controversial issue. Results suggest that it is the activation magnitude of SI, which solely establishes the significant correlation with subjective pain ratings, in accordance with the classical clinical thinking, relating SI lesions to diminished perception of pain. Although this study cannot support a causal relation between SI activation magnitude and pain perception, such relation might be insinuated. © 2008 American Pain Society.

120. Mulert, C., O. Pogarell, and U. Hegerl, Simultaneous EEG-fMRI: Perspectives in psychiatry. Clinical EEG and Neuroscience, 2008. 39(2): p. 61-64.

Summary: Neurophysiological findings such as reduced amplitudes of the P300 potential in patients with schizophrenia are among the most robust findings in biological psychiatry. An enormous literature with findings of abnormal central processing in psychiatric diseases has been acquired during the last decades. However, the benefit of this research has been limited in part due to the unresolved problem of precise and correct localization of the underlying neural generators. The difficulty of correct localization is due to the fact that different constellations of cortical neuroelectric generators can produce identical EEG activity. Therefore, even concerning several major event related potentials no generally accepted knowledge about their cerebral generation exists. While correct localization can easily be obtained by imaging methods based on hemodynamic changes such as functional magnetic resonance imaging (fMRI), these techniques can not distinguish between different aspects of neural activity such as oscillation modes or stages of information processing that are only some milliseconds apart. Accordingly, the integration of simultaneous measurements of EEG and fMRI has become a methodological key issue today. EEG-fMRI may prove to be crucial in providing much deeper understanding of brain activity over the next decades. This review summarizes the basic physiology, methodological issues and interesting applications in psychiatry.

121. Moazami-Goudarzi, M., J. Sarnthein, L. Michels, R. Moukhtieva, and D. Jeanmonod, Enhanced frontal low and high frequency power and synchronization in the resting EEG of parkinsonian patients. NeuroImage, 2008. 41(3): p. 985-997.

Summary: Oscillatory and coherent EEG activity is increasingly recognized as a fundamental hallmark of cortical integrative functions. We aimed to study deviations from the norm of different resting EEG parameters in Parkinson's disease (PD) patients. We compared spectral parameters of the resting EEG of PD patients (n = 24, median age 67 years) to those of healthy controls (n = 34, median age 62 years). On average, the patient group exhibited higher spectral power over the frequency range of 2-100 Hz, and the dominant peak was shifted towards lower frequencies. Maximal differences appeared in the 6-9 Hz theta band in all electrodes. Frontal electrodes contributed most to this difference in the 4-6 Hz theta, 12-18 Hz beta and 30-45 Hz gamma bands. On an individual basis, the combination of six spectral power band parameters discriminated between patient and control groups and 72% of all subjects were classified correctly. Using LORETA source analysis, the generators of this power difference were localized to fronto-insulo-temporal cortical areas in the theta and beta bands, and to interhemispheric frontal (supplementary motor area, SMA) and cingulate areas in the 30-45 Hz gamma band. We calculated spectral coherence between electrode pairs in a frontal, central and parietal region of interest (ROI). In the frontal ROI, coherence was enhanced significantly in the patient group in the theta, high beta and gamma bands. In the parietal ROI, patients showed lower coherence around 10 Hz. We demonstrate a deviation from the norm of different resting EEG parameters in PD patients. This evidence can be integrated in the context of a pathophysiological chain reaction initiated in the substantia nigra and resulting in a cortical aberrant dynamics rooted in enhanced dysrhythmic thalamocortical interactions. © 2008 Elsevier Inc. All rights reserved.

122. Marzetti, L., C. Del Gratta, and G. Nolte, Understanding brain connectivity from EEG data by identifying systems composed of interacting sources. NeuroImage, 2008. 42(1): p. 87-98.

Summary: In understanding and modeling brain functioning by EEG/MEG, it is not only important to be able to identify active areas but also to understand interference among different areas. The EEG/MEG signals result from the superimposition of underlying brain source activities volume conducted through the head. The effects of volume conduction produce spurious interactions in the measured signals. It is fundamental to separate true source interactions from noise and to unmix the contribution of different systems composed by interacting sources in order to understand interference mechanisms. As a prerequisite, we consider the problem of unmixing the contribution of uncorrelated sources to a measured field. This problem is equivalent to the problem of unmixing the contribution of different uncorrelated compound systems composed by interacting sources. To this end, we develop a principal component analysis-based method, namely, the source principal component analysis (sPCA), which exploits the underlying assumption of orthogonality for sources, estimated from linear inverse methods, for the extraction of essential features in signal space. We then consider the problem of demixing the contribution of correlated sources that comprise each of the compound systems identified by using sPCA. While the sPCA orthogonality assumption is sufficient to separate uncorrelated systems, it cannot separate the individual components within each system. To address that problem, we introduce the Minimum Overlap Component Analysis (MOCA), employing a pure spatial criterion to unmix pairs of correlates (or coherent) sources. The proposed methods are tested in simulations and applied to EEG data from human μ and α rhythms. © 2008 Elsevier Inc. All rights reserved.

123. Ma, X. and J. Zou, Combined source simulation method-Fictitious medium method for solving anisotropic EEG problems. ISAPE 2008 - The 8th International Symposium on Antennas, Propagation and EM Theory Proceedings, 2008: p. 925-928.

Summary: An electroencephalography (EEG) problem in bio-electromagnetics is to estimate dipolar current sources inside the brain from the measured electric potential distribution on the scalp surface. Traditional linear algorithms are the low-resolution electromagnetic tomography algorithms (LORETA) including improved ones. It is easy to solve isotropic EEG problems by means of them. But the skull conductivity is anisotropic obviously. In this paper, proposed is a source simulation method combined with the fictitious medium method for solving the anisotropic skull layer problem to obtain the electric potential and field intensity on the cortex. Then it can be connected with LORETA. A good agreement between the numerical result and analytical result of the 4-layer spherical head model has been observed. It is shown that this method is effective and feasible. Its prominent advantages are simple and timesaving. And this numerical computation method is suitable for not only spherical head models but also realistic head models with the thin anisotropic layer. © 2008 IEEE.

124. Lorenzo-López, L., E. Amenedo, R.D. Pascual-Marqui, and F. Cadaveira, Neural correlates of age-related visual search decline: A combined ERP and sLORETA study. NeuroImage, 2008. 41(2): p. 511-524.

Summary: Differences in the neural systems underlying visual search processes for young (n = 17, mean age 19.6 ± 1.9) and older (n = 22, mean age 68.5 ± 6) subjects were investigated combining the Event-Related Potential (ERP) technique with standardized Low-Resolution brain Electromagnetic Tomography (sLORETA) analyses. Behavioral results showed an increase in mean reaction times (RTs) and a reduction in hit rates with age. The ERPs were significantly different between young and older subjects at the P3 component, showing longer latencies and lower amplitudes in older subjects. These ERP results suggest an age-related decline in the intensity and speed of visual processing during visual search that imply a reduction in attentional resources with normal aging. The sLORETA data revealed a significantly reduced neural differentiation in older subjects, who recruited bilateral prefrontal regions in a nonselective manner for the different search arrays. Finally, sLORETA between-group comparisons revealed that relative to young subjects, older subjects showed significantly reduced activity in anterior cingulate cortex as well as in numerous limbic and occipitotemporal regions contributing to visual search processes. These findings provide evidence that the neural circuit supporting this cognitive process is vulnerable to normal aging. All these attentional factors could contribute to poorer performance of older compared to young subjects in visual search tasks. © 2008 Elsevier Inc. All rights reserved.

125. Liu, Z. and B. He, fMRI-EEG integrated cortical source imaging by use of time-variant spatial constraints. NeuroImage, 2008. 39(3): p. 1198-1214.

Summary: In response to the need of establishing a high-resolution spatiotemporal neuroimaging technique, tremendous efforts have been focused on developing multimodal strategies that combine the complementary advantages of high-spatial-resolution functional magnetic resonance imaging (fMRI) and high-temporal-resolution electroencephalography (EEG) or magnetoencephalography (MEG). A critical challenge to the fMRI-EEG/MEG integration lies in the spatial mismatches between fMRI activations and instantaneous electrical source activities. Such mismatches are fundamentally due to the fact that fMRI and EEG/MEG signals are generated and collected in highly different time scales. In this paper, we propose a new theoretical framework to solve the problem of fMRI-EEG integrated cortical source imaging. The new framework has two principal technical advancements. First, by assuming a linear neurovascular coupling, a method is derived to quantify the fMRI signal in each voxel as proportional to the time integral of the power of local electrical current during the period of event-related potentials (ERP). Second, the EEG inverse problem is solved for every time instant using an adaptive Wiener filter, in which the prior time-variant source covariance matrix is estimated by combining the quantified fMRI responses and the segmented EEG signals before response averaging. A series of computer simulations were conducted to evaluate the proposed methods in terms of imaging the instantaneous cortical current density (CCD) distribution and estimating the source time courses with a millisecond temporal resolution. As shown in the simulation results, the instantaneous CCD reconstruction by using the proposed fMRI-EEG integration method was robust against both fMRI false positives and false negatives while retaining a spatial resolution nearly as high as that of fMRI. The proposed method could also reliably estimate the source waveforms when multiple sources were temporally correlated or uncorrelated, or were sustained or transient, or had some features in frequency or phase, or had even more complicated temporal dynamics. Moreover, applying the proposed method to real fMRI and EEG data acquired in a visual experiment yielded a time series of reconstructed CCD images, in agreement with the traditional view of hierarchical visual processing. In conclusion, the proposed method provides a reliable technique for the fMRI-EEG integration and represents a significant advancement over the conventional fMRI-weighted EEG (or MEG) source imaging techniques and is also applicable to the fMRI-MEG integrated source imaging. © 2007 Elsevier Inc. All rights reserved.

126. Li, W., R.E. Zinbarg, S.G. Boehm, and K.A. Paller, Neural and behavioral evidence for affective priming from unconsciously perceived emotional facial expressions and the influence of trait anxiety. Journal of Cognitive Neuroscience, 2008. 20(1): p. 95-107.

Summary: Affective judgments can often be influenced by emotional information people unconsciously perceive, but the neural mechanisms responsible for these effects and how they are modulated by individual differences in sensitivity to threat are unclear. Here we studied subliminal affective priming by recording brain potentials to surprise faces preceded by 30-msec happy or fearful prime faces. Participants showed valence-consistent changes in affective ratings of surprise faces, although they reported no knowledge of prime-face expressions, nor could they discriminate between prime-face expressions in a forced-choice test. In conjunction with the priming effect on affective evaluation, larger occipital P1 potentials at 145-175 msec were found with fearful than with happy primes, and source analyses implicated the bilateral extrastriate cortex in this effect. Later brain potentials at 300-400 msec were enhanced with happy versus fearful primes, which may reflect differential attentional orienting. Personality testing for sensitivity to threat, especially social threat, was also used to evaluate individual differences potentially relevant to subliminal affective priming. Indeed, participants with high trait anxiety demonstrated stronger affective priming and greater P1 differences than did those with low trait anxiety, and these effects were driven by fearful primes. Results thus suggest that unconsciously perceived affective information influences social judgments by altering very early perceptual analyses, and that this influence is accentuated to the extent that people are oversensitive to threat. In this way, perception may be subject to a variety of influences that govern social preferences in the absence of concomitant awareness of such influences. © 2008 Massachusetts Institute of Technology.

127. Lee, H.K., D.H. Park, H.S. Shin, and S.C. Hong, Comparison of low resolution electromagnetic tomography imaging between subjects with mild and severe obstructive sleep apnea syndrome: A preliminary study. Psychiatry Investigation, 2008. 5(1): p. 45-51.

Summary: Objective: The purpose of this study was to identify the regions of the brain associated with recurrent nocturnal chronic hypoxic episodes in patients with untreated obstructive sleep apnea syndrome (OSAS) using low-resolution electromagnetic tomography (LORETA) and quantitative electroencephalography (QEEG). Methods: Nocturnal polysomnograph (NPSG) and subsequent morning electroencephalograph (EEG) were measured in 20 subjects with OSAS. Mild (n=10 ages 39.5 ± 12.1 years) and severe (n=10 ages 41.7 ± 13.6 years) right-handed male OSAS subjects were selected by interview and questionnaires including the NPSG, Beck Depression Inventory, Beck Anxiety Inventory, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index. The LORETA and QEEG were compared between the severe and mild OSAS groups by frequency bands (delta 1-3 Hz, theta 4-7 Hz, alpha 8-12 Hz, betal 13-18 Hz, beta2 19-21 Hz, beta3 22-30 Hz, and total 1-30 Hz) made by spectral analysis during resting with the eyes closed. Results: The LORETA analysis showed decreased alpha activity at the right posterior cingulate gyrus (Brodmann area 23) in cases with severe OSAS compared to mild OSAS (p<0.05). For the QEEG, the absolute power of the alpha activity (8-12 Hz) was decreased in P3 (p=0.047), PZ (p=0.039) and O2 (p=0.04) in cases with severe OSAS compared to mild OSAS cases. The LORETA and QEEG analyses had similar results with regard to band, activation and location. Conclusion: The decreased activity of the alpha frequency in the right posterior cingulate gyrus, in patients with severe OSAS compared to those with mild OSAS, suggests that chronic repeated short-term hypoxia during sleep, in OSAS, could provoke cortical brain dysfunction associated with cognitive dysfunction such as memory and attention. Copyright © 2008 Official Journal of Korean Neuropsychiatric Association.

128. Lavric, A., G.A. Mizon, and S. Monsell, Neurophysiological signature of effective anticipatory task-set control: A task-switching investigation. European Journal of Neuroscience, 2008. 28(5): p. 1016-1029.

Summary: Changing between cognitive tasks requires a reorganization of cognitive processes. Behavioural evidence suggests this can occur in advance of the stimulus. However, the existence or detectability of an anticipatory task-set reconfiguration process remains controversial, in part because several neuroimaging studies have not detected extra brain activity during preparation for a task switch relative to a task repeat. In contrast, electrophysiological studies have identified potential correlates of preparation for a task switch, but their interpretation is hindered by the scarcity of evidence on their relationship to performance. We aimed to: (i) identify the brain potential(s) reflecting effective preparation for a task-switch in a task-cuing paradigm that shows clear behavioural evidence for advance preparation, and (ii) characterize this activity by means of temporal segmentation and source analysis. Our results show that when advance preparation was effective (as indicated by fast responses), a protracted switch-related component, manifesting itself as widespread posterior positivity and concurrent right anterior negativity, preceded stimulus onset for ∼300 ms, with sources primarily in the left lateral frontal, right inferior frontal and temporal cortices. When advance preparation was ineffective (as implied by slow responses), or made impossible by a short cue-stimulus interval (CSI), a similar component, with lateral prefrontal generators, peaked ∼300 ms poststimulus. The protracted prestimulus component (which we show to be distinct from P3 or contingent negative variation, CNV) also correlated over subjects with a behavioural measure of preparation. Furthermore, its differential lateralization for word and picture cues was consistent with a role for verbal self-instruction in preparatory task-set reconfiguration. © The Authors (2008).

129. Kopecek, M., B. Tislerova, P. Sos, M. Bares, T. Novak, V. Krajca, and M. Brunovsky, QEEG changes during switch from depression to hypomania/mania: A case report. Neuroendocrinology Letters, 2008. 29(3): p. 295-302.

Summary: Background: QEEG cordance and low-resolution electromagnetic tomography (LORETA) are relatively new applications of QEEG. Four small-scale studies have shown that decreases of QEEG prefrontal theta cordance after the first week on new antidepressants predict clinical response to treatment in patients with unipolar depression. Methods: We calculated prefrontal theta cordance and changes in 3D distribution of brain electrical activity using LORETA in the case of a 54-year old man experiencing his third depressive episode. Results: We did not detect a decrease of prefrontal theta cordance after one week of new treatment and the patient did not respond to this therapy after four weeks. However, we observed a decrease of prefrontal theta cordance after the first week of clomipramine therapy. Manic symptoms emerged after two weeks of clomipramine treatment. A decrease of prefrontal theta cordance preceded the clomipramine induced switch to hypomania during the next episode of depression also. LORETA before and during clomipramine therapies detected a significant increase of theta in the right postcentralis gyrus in the parietal lobe, and a borderline increase of alfa2 in the right middle frontal gyrus. Discussion: In a patient with bipolar spectrum disorder we found that a treefold change in theta prefrontal cordance preceded mood changes in a similar way as in patients with unipolar depression. We speculate that the changes detected by LORETA can attributed to the anticholinergic activity of clomipramine and the specific effects of a mood switch. Our data suggest that the new applications of QEEG can be sensitive to mood changes and have potential in bipolar disorder research. © 2008 Neuroendocrinology Letters.

130. Khemakhem, R., W. Zouch, A. Taleb-Ahmed, and A.B. Hamida, A new combining approach to localizing the EEG activity in the brain: WMN and LORETA solution. BioMedical Engineering and Informatics: New Development and the Future - Proceedings of the 1st International Conference on BioMedical Engineering and Informatics, BMEI 2008, 2008. 1: p. 821-824.

Summary: Estimation of cerebral electric activity from the scalp electroencephalogram EEG requires a solution to the EEG inverse problem. We propose a new approach which consists in combining two methods in order to locate the brain electric activity: 'Weighted Minimum Norm' 'WMN' and 'LOw Resolution brain Electromagnetic TomogrAphy' 'LORETA'. The idea that we propose is to used the current density distribution estimated by the WMN method in order to initialize the LORETA method. A comparative study of three different inverse methods, WMN, LORETA and WMN-LORETA is presented. We compare the results found with existing methods LORETA and WMN. The results reveal that WMN-LORETA is able to reconstruct a three-dimensional source distribution with a degree of localization compared to the other methods. © 2008 IEEE.

131. Khemakhem, R., A.B. Hamida, A. Ahmed-Taleb, and P. Derambure, New hybrid method for the 3D reconstruction of neuronal activity in the brain. Proceedings of IWSSIP 2008 - 15th International Conference on Systems, Signals and Image Processing, 2008: p. 405-408.

Summary: Estimation of the electrical cartography on the scalp surface requires a solution to the EEG inverse problem, but, there is no unique solution to this problem. In this paper we present Standardized LOw Resolution brain Electromagnetic TomogrAphy "sLORETA", the FOCaI Underdetermined System Solver "FOCUSS", and the new combination solution "sLORET A-FOCUSS" methods. The purpose of this paper is to present the technical details of these methods, and give some comparison between them. The results demonstrate that using each method, we obtain different results given the reconstruction in 3D of the cerebral activity in the brain from where we evaluate the efficiency of the sLORETA-FOCUSS method to reconstruct a three dimensional source distribution with smaller localization and a minimum of localization error.

132. Khader, P., T. Schicke, B. Röder, and F. Rösler, On the relationship between slow cortical potentials and BOLD signal changes in humans. International Journal of Psychophysiology, 2008. 67(3): p. 252-261.

Summary: This review summarizes experimental studies that investigated the relationship between DC-recorded slow event-related potentials (slow waves) of the electroencephalogram (EEG) and the hemodynamic BOLD response, as measured with functional magnetic resonance imaging (fMRI). Slow waves have been found to accompany a large number of cognitive processes in a systematic and topographically specific way, and have thus been successfully employed in psychophysiological experiments to dissociate cognitive functions by means of their slow wave topography. Recently, however, several independent studies, using different experimental paradigms, suggest the existence of another feature of slow waves, i.e., a close relationship with the fMRI BOLD response. Some of these studies found couplings between slow waves and BOLD signals in various brain regions, using simultaneous EEG-fMRI recordings. Others found similar task-related activation patterns of slow waves (i.e., scalp topographies) and BOLD responses (i.e., activated voxel profiles), as well as corresponding parametric increases of signal strength with increasing task difficulty. The close relationship between slow waves and BOLD responses reported here concerns a low frequency range of the EEG signal (< 1 Hz) that has so far received less attention in studies on the correspondence between EEG and fMRI than the higher frequencies, and therefore adds to the various findings obtained at higher EEG frequencies. Implications for the use of slow waves for neuroscientific research are discussed. © 2007 Elsevier B.V. All rights reserved.

133. Hyun, J.S., S.C. Kam, and O.Y. Kwon, Changes of cerebral current source by audiovisual erotic stimuli in premature ejaculation patients. Journal of Sexual Medicine, 2008. 5(6): p. 1474-1481.

Summary: Introduction. Premature ejaculation (PE) is one of the most common forms of male sexual dysfunction. The mechanisms of PE remain poorly understood, despite its high prevalence. Aim. To investigate the pathophysiology and casuses of PE in the central nervous system, we tried to observe the changes in brain current source distribution by audiovisual induction of sexual arousal. Methods. Electroencephalograpies were recorded in patients with PE (45.0 ± 10.3 years old, N = 18) and in controls (45.6 ± 9.8 years old, N = 18) during four 10-minute segments of resting, watching a music video excerpt, resting, and watching an erotic video excerpt. Five artifact-free 5-second segments were used to obtain cross-spectral low-resolution brain electromagnetic tomography (LORETA) images. Main Outcome Measures. Statistical nonparametric maps (SnPM) were obtained to detect the current density changes of six frequency bands between the erotic video session and the music video session in each group. Comparisons were also made between the two groups in the erotic video session. Results. In the SnPM of each spectrum in patients with PE, the current source density of the alpha band was significantly reduced in the right precentral gyrus, the right insula, and both superior parietal lobules (P < 0.01). Comparing the two groups in the erotic video session, the current densities of the beta-2 and -3 bands in the PE group were significantly decreased in the right parahippocampal gyrus and left middle temporal gyrus (P & lt;0.01). Conclusions. Neuronal activity in the right precental gyrus, the right insula, both the superior parietal lobule, the right parahippocampal gyrus, and the left middle temporal gyrus may be decreased in PE patients upon sexual arousal. Further studies are needed to evaluate the meaning of decreased neuronal activities in PE patients. © 2008 International Society for Sexual Medicine.

134. Hori, T., K. Ogawa, T. Abe, and H. Nittono, Brain potentials related to rapid eye movements and dreaming during REM sleep: A short review of psychophysiological correlates. Sleep and Biological Rhythms, 2008. 6(3): p. 128-138.

Summary: Many sleep researchers have examined dream image-generation, which occurs during rapid eye movement (REM) sleep. Furthermore, activation of brain regions related to rapid eye movements during human REM sleep has been reported. Although recent brain imaging techniques have high spatial resolution, their temporal resolution is limited. Consequently, the spatio-temporal structures of brain activities related to rapid eye movement remain largely unknown. This article presents a short review of findings of recent studies that have used brain potentials related to rapid eye movement to examine dream image-generation processes. Brain potentials related to rapid eye movement are obtained using averaged electroencephalography (EEG) that is time-locked to the onset or offset of rapid eye movement. First, based on findings related to presaccadic and pre-REM brain potentials, we discuss why eyes move during REM sleep. Second, the relationship of lambda-like potentials, which occur immediately after the cessation of rapid eye movement, to generation of visual dream images, is discussed. Third, enhancement of gamma-band EEG activity occurring immediately after the offset of rapid eye movement is discussed in terms of information-binding of dream images. Finally in this review, preparatory activation of emotion and memory circuits before the onset of rapid eye movement is discussed in terms of contextual setting of the dream story. © 2008 The Author Journal compilation © 2008 Japanese Society of Sleep Research.

135. Holz, E.M., M. Doppelmayr, W. Klimesch, and P. Sauseng, EEG correlates of action observation in humans. Brain Topography, 2008. 21(2): p. 93-99.

Summary: To investigate electrophysiological correlates of action observation electroencephalogram (EEG) was recorded while participants observed repetitive biological (human) or non-biological movements (at a rate of 2 Hz). Steady-state evoked potentials were analyzed and their neural sources were investigated using low resolution electromagnetic tomography analysis (LORETA). Results revealed significantly higher activation in the primary motor and premotor cortex, supplementary motor area as well as the posterior parietal cortices during observation of biological movements, supporting mirror properties of cortical motor neurons. In addition interregional communication was analyzed. Increased coherence for distributed networks at delta (0.5-4 Hz) and lower alpha (8-10 Hz) frequencies were obtained suggesting integration and functional coupling between the activated cortical regions during human action observation. © 2008 Springer Science+Business Media, LLC.

136. Holmes, A.J. and D.A. Pizzagalli, Spatiotemporal dynamics of error processing dysfunctions in major depressive disorder. Archives of General Psychiatry, 2008. 65(2): p. 179-188.

Summary: Context: Depression is characterized by executive dysfunctions and abnormal reactions to errors; however, little is known about the brain mechanisms that underlie these deficits. Objective: To examine whether abnormal reactions to errors in patients with major depressive disorder (MDD) are associated with exaggerated paralimbic activation and/or a failure to recruit subsequent cognitive control to account for mistakes in performance. Design: Between February 15, 2005, and January 19, 2006, we recorded 128-channel event-related potentials while study participants performed a Stroop task, modified to incorporate performance feedback. Setting: Patients with MDD and healthy comparison subjects were recruited from the general community. Participants: Study participants were 20 unmedicated patients with MDD and 20 demographically matched comparison subjects. Main Outcome Measures: The error-related negativity and error positivity were analyzed through scalp and source localization analyses. Functional connectivity analyses were conducted to investigate group differences in the spatiotemporal dynamics of brain mechanisms that underlie error processing. Results: Relative to comparison subjects, patients with MDD displayed significantly lower accuracy after incorrect responses, larger error-related negativity, and higher current density in the rostral anterior cingulate cortex (ACC) and medial prefrontal cortex (PFC) (Brodmann area 10/32) 80 milliseconds after committing an error. Functional connectivity analyses revealed that for the comparison subjects, but not the patients with MDD, rostral ACC and medial PFC activation 80 milliseconds after committing an error predicted left dorsolateral PFC (Brodmann area 8/9) activation 472 milliseconds after committing an error. Conclusions: Unmedicated patients with MDD showed reduced accuracy and potentiated error-related negativity immediately after committing errors, highlighting dysfunctions in the automatic detection of unfavorable performance outcomes. New analytic procedures allowed us to show that abnormal reaction to committing errors was accompanied by hyperactivation in rostral ACC and medial PFC regions 80 milliseconds after committing errors and a failure to recruit dorsolateral PFC-based cognitive control. Future studies are warranted to investigate whether these dysfunctions might foster the emergence and maintenance of negative processing biases and thus increase vulnerability to depression. ©2008 American Medical Association. All rights reserved.

137. Holmes, A.J. and D.A. Pizzagalli, Response conflict and frontocingulate dysfunction in unmedicated participants with major depression. Neuropsychologia, 2008. 46(12): p. 2904-2913.

Summary: Individuals with major depressive disorder (MDD) often exhibit impaired executive function, particularly in experimental tasks that involve response conflict and require adaptive behavioral adjustments. Prior research suggests that these deficits might be due to dysfunction within frontocingulate pathways implicated in response conflict monitoring and the recruitment of cognitive control. However, the temporal unfolding of conflict monitoring impairments in MDD remains poorly understood. To address this issue, we recorded 128-channel event-related potentials while 20 unmedicated participants with MDD and 20 demographically matched, healthy controls performed a Stroop task. Compared to healthy controls, MDD subjects showed larger Stroop interference effects and reduced N2 and N450 amplitudes. Source localization analyses at the time of maximal N450 activity revealed that MDD subjects had significantly reduced dorsal anterior cingulate cortex (dACC; Brodmann area 24/32) and left dorsolateral prefrontal cortex (Brodmann area 10/46) activation to incongruent relative to congruent trials. Consistent with the heterogeneous nature of depression, follow-up analyses revealed that depressed participants with the lowest level of conflict-related dACC activation 620 ms post-stimulus were characterized by the largest Stroop interference effects (relatively increased slowing and reduced accuracy for incongruent trials). Conversely, MDD participants with relatively stronger dACC recruitment did not differ from controls in terms of interference effects. These findings suggest that for some, but not all individuals, MDD is associated with impaired performance in trials involving competition among different response options, and reduced recruitment of frontocingulate pathways implicated in conflict monitoring and cognitive control. © 2008 Elsevier Ltd. All rights reserved.

138. Hensch, T., U. Herold, K. Diers, D. Armbruster, and B. Brocke, Reliability of intensity dependence of auditory-evoked potentials. Clinical Neurophysiology, 2008. 119(1): p. 224-236.

Summary: Objective: Intensity dependence of auditory-evoked potentials (IAEP) is a suggested indicator of serotonergic neurotransmission. In contrast to its clinical renaissance, the reliability of IAEP has only been examined in a few studies, most of which are limited due to the possibly confounding effects of age and gender. Therefore, the present study examines different reliabilities of various IAEP parameterizations while controlling for age and gender. Methods: Auditory-evoked potentials were recorded from 166 students. Of these 37 women and 25 men were retested after three weeks. Results: Test-retest and odd-even reliabilities were remarkable at Cz in both females (r = .88/.86) and males (r = .82/.79). Reliabilities were higher in women, higher with linear than median slopes and best at Cz. Bisection of sweep number, split-half reliability, the second run, and lower intensities revealed lower reliabilities. Conclusions: Reliabilities at Cz can reach the same level as previously reported by dipole-source-localization methods, if sufficient sweep number and linear slopes are applied. Significance: Based on theoretical arguments and current data, the continued use of the easy and rapidly done single-channel IAEP is suggested, although ideally in combination with multi-channel source-localization methods. This would be seminal for a drafted program standardizing IAEP to further improve its clinical utility. © 2007 International Federation of Clinical Neurophysiology.

139. Haufe, S., V.V. Nikulin, A. Ziehe, K.R. Müller, and G. Nolte, Combining sparsity and rotational invariance in EEG/MEG source reconstruction. NeuroImage, 2008. 42(2): p. 726-738.

Summary: We introduce Focal Vector Field Reconstruction (FVR), a novel technique for the inverse imaging of vector fields. The method was designed to simultaneously achieve two goals: a) invariance with respect to the orientation of the coordinate system, and b) a preference for sparsity of the solutions and their spatial derivatives. This was achieved by defining the regulating penalty function, which renders the solutions unique, as a global ℓ1-norm of local ℓ2-norms. We show that the method can be successfully used for solving the EEG inverse problem. In the joint localization of 2-3 simulated dipoles, FVR always reliably recovers the true sources. The competing methods have limitations in distinguishing close sources because their estimates are either too smooth (LORETA, Minimum ℓ1-norm) or too scattered (Minimum ℓ2-norm). In both noiseless and noisy simulations, FVR has the smallest localization error according to the Earth Mover's Distance (EMD), which is introduced here as a meaningful measure to compare arbitrary source distributions. We also apply the method to the simultaneous localization of left and right somatosensory N20 generators from real EEG recordings. Compared to its peers FVR was the only method that delivered correct location of the source in the somatosensory area of each hemisphere in accordance with neurophysiological prior knowledge. © 2008 Elsevier Inc. All rights reserved.

140. Haiman, G., H. Pratt, and A. Miller, Brain responses to verbal stimuli among multiple sclerosis patients with pseudobulbar affect. Journal of the Neurological Sciences, 2008. 271(1-2): p. 137-147.

Summary: Purpose: To characterize the brain activity and associated cortical structures involved in pseudobulbar affect (PBA), a condition characterized by uncontrollable episodes of emotional lability in patients with multiple sclerosis (MS). Methods: Behavioral responses and event related potentials (ERP) in response to subjectively significant and neutral verbal stimuli were recorded from 33 subjects in 3 groups: 1) MS patients with PBA (MS + PBA); 2) MS patients without PBA (MS); 3) Healthy control subjects (HC). Statistical non-parametric mapping comparisons of ERP source current density distributions between groups were conducted separately for subjectively significant and for neutral stimuli. Results: Behavioral responses showed more impulsive performance in patients with PBA. As expected, almost all ERP waveform comparisons between the MS groups and controls were significant. Source analysis indicated significantly distinct activation in MS + PBA in the vicinity of the somatosensory and motor areas in response to neutral stimuli, and at pre-motor and supplementary motor areas in response to subjectively significant stimuli. Both subjectively significant and neutral stimuli evoked higher current density in MS + PBA compared to both other groups. Conclusions: PBA of MS patients involves cortical structures related to sensory-motor and emotional processing, in addition to overactive involvement of motor cortical areas in response to neutral stimuli. Significance: These results may suggest that a 'disinhibition' of a "gate control"-type mechanism for emotional expression may lead to the lower emotional expression threshold of pseudobulbar affect. © 2008 Elsevier B.V. All rights reserved.

141. Godinho, F., M. Frot, C. Perchet, M. Magnin, and L. Garcia-Larrea, Pain influences hedonic assessment of visual inputs. European Journal of Neuroscience, 2008. 27(9): p. 2219-2228.

Summary: It is acknowledged that the emotional state created by visual inputs can modulate the way we feel pain; however, little is known about how acute pain influences the emotional assessment of what we see. In this study healthy subjects scored affective images while receiving painful or innocuous electrical shocks. Painful stimuli did not make unpleasant images more unpleasant, but rendered pleasant pictures significantly less pleasant. Brain responses to visual inputs (64-channels electroencephalogram) mirrored behavioural results, showing pain-induced effects in the orbitofrontal cortex, the subgenual portion of the cingulate gyrus, the anterior prefrontal and the temporal cortices, exclusively during presentation of pleasant images. In addition to this specific effect on pleasant pictures, pain also produced non-specific effects upon all categories of images, engaging cerebral areas associated with attention, alertness and motor preparation (middle-cingulate, supplemental motor, prefrontal cortex). Thus, pain appears to have a dual influence on visual processing: a non-specific effect related to orienting phenomena; and a more specific action exerted on supra-modal limbic areas involved in the production of affective states. The latter correlated with changes in the subjective appraisal of visual stimuli, and may underlie not only the change in their subjective assessment but also reactive processes aimed at coping with unpleasant contexts. © The Authors (2008).

142. Gianotti, L.R.R., G. Künig, P.L. Faber, D. Lehmann, R.D. Pascual-Marqui, K. Kochi, and U. Schreiter-Gasser, Rivastigmine effects on EEG spectra and three-dimensional LORETA functional imaging in Alzheimer's disease. Psychopharmacology, 2008. 198(3): p. 323-332.

Summary: Objective: The objective of the study is to investigate the electrocortical and the global cognitive effects of 3 months rivastigmine medication in a group of mild to moderate Alzheimer's disease patients. Materials and methods: Multichannel EEG and cognitive performances measured with the Mini Mental State Examination in a group of 16 patients with mild to moderate Alzheimer's Disease were collected before and 3 months after the onset of rivastigmine medication. Results: Spectral analysis of the EEG data showed a significant power decrease in the delta and theta frequency bands during rivastigmine medication, i.e., a shift of the power spectrum towards 'normalization'. Three-dimensional low resolution electromagnetic tomography (LORETA) functional imaging localized rivastigmine effects in a network that includes left fronto-parietal regions, posterior cingulate cortex, bilateral parahippocampal regions, and the hippocampus. Moreover, a correlation analysis between differences in the cognitive performances during the two recordings and LORETA-computed intracortical activity showed, in the alpha1 frequency band, better cognitive performance with increased cortical activity in the left insula. Conclusion: The results point to a 'normalization' of the EEG power spectrum due to medication, and the intracortical localization of these effects showed an increase of cortical activity in frontal, parietal, and temporal regions that are well-known to be affected in Alzheimer's disease. The topographic convergence of the present results with the memory network proposed by Vincent et al. (J. Neurophysiol. 96:3517-3531, 2006) leads to the speculation that in our group of patients, rivastigmine specifically activates brain regions that are involved in memory functions, notably a key symptom in this degenerative disease. © 2008 Springer-Verlag.

143. Galka, A., T. Ozaki, H. Muhle, U. Stephani, and M. Siniatchkin, A data-driven model of the generation of human EEG based on a spatially distributed stochastic wave equation. Cognitive Neurodynamics, 2008. 2(2): p. 101-113.

Summary: We discuss a model for the dynamics of the primary current density vector field within the grey matter of human brain. The model is based on a linear damped wave equation, driven by a stochastic term. By employing a realistically shaped average brain model and an estimate of the matrix which maps the primary currents distributed over grey matter to the electric potentials at the surface of the head, the model can be put into relation with recordings of the electroencephalogram (EEG). Through this step it becomes possible to employ EEG recordings for the purpose of estimating the primary current density vector field, i.e. finding a solution of the inverse problem of EEG generation. As a technique for inferring the unobserved high-dimensional primary current density field from EEG data of much lower dimension, a linear state space modelling approach is suggested, based on a generalisation of Kalman filtering, in combination with maximum-likelihood parameter estimation. The resulting algorithm for estimating dynamical solutions of the EEG inverse problem is applied to the task of localising the source of an epileptic spike from a clinical EEG data set; for comparison, we apply to the same task also a non-dynamical standard algorithm. © 2008 Springer Science+Business Media B.V.

144. Fisher, D.J., A. Labelle, and V.J. Knott, The right profile: Mismatch negativity in schizophrenia with and without auditory hallucinations as measured by a multi-feature paradigm. Clinical Neurophysiology, 2008. 119(4): p. 909-921.

Summary: Objective: To examine pre-attentive acoustic change detection in schizophrenia patients with and without auditory hallucinations via mismatch negativity (MMN) extracted from a multi-feature paradigm. Methods: This study examined the electroencephalograph (EEG)-derived MMN, recorded across 32 sites, in 12 hallucinating patients (HPs) with schizophrenia, 12 non-hallucinating patients (NPs) with schizophrenia and 12 healthy controls (HCs). MMN was recorded in response to a multi-feature MMN paradigm [Näätänen, R., et al., 2004. The mismatch negativity (MMN): towards the optimal paradigm. Clin. Neurophys. 115, 140-144] which employs frequency, duration, intensity, location and gap deviants. Differences in source localization were probed using standardized low resolution brain electromagnetic tomography (sLORETA). Results: HPs showed significantly smaller MMNs to duration deviants compared to HCs and NPs, as well as smaller MMNs to intensity deviants compared to HCs. Regionalized differences between HCs and each of the patient groups were observed in response to frequency deviants. There were no significant group effects for location or gap deviants, or for MMN latency. Source localization using sLORETA showed no significant differences in MMN generator location across groups for any of the deviant stimuli. Conclusions: The often-reported robust MMN deficit to duration deviants may be specific to schizophrenia patients afflicted with auditory hallucinations. Furthermore, by using symptom-specific groups, novel deficits of pre-attentive auditory processing, such as that observed to intensity deviants in HPs, may be revealed. Significance: The differential responding observed between both groups of patients with schizophrenia has implications for automatic processing within the auditory cortex of hallucinating patients and suggests that care must be taken when recruiting participants in studies involving schizophrenia to ensure consistent, replicable results. © 2007 International Federation of Clinical Neurophysiology.

145. Esslen, M., S. Metzler, R. Pascual-Marqui, and L. Jancke, Pre-reflective and reflective self-reference: A spatiotemporal EEG analysis. NeuroImage, 2008. 42(1): p. 437-449.

Summary: Functional imaging studies consistently support the role of the medial prefrontal cortex to be a part of a functional network of reflective self-awareness. The current study introduces a new linguistic task which (1) directly compares self-reference and other-reference, and (2) separates pre-reflective from reflective aspects of self-awareness. Twenty-six healthy volunteers evaluated trait adjectives in reference to the self or a close friend while a continuous 30-channel EEG was recorded. Low-resolution brain electromagnetic tomography (LORETA) was used for statistical brain imaging. As expected, the direct comparison of self-reference to other-reference revealed the MPFC to be significant and strongly more active during the self-reference condition. Pre-reflective aspects of self seem to be implemented to a greater degree in the ventral, reflective aspects of the self in dorsal parts of the MPFC. In the pre-reflective self condition, brain areas that receive homeostatic afferents from somatic and visceral sensation of the body such as the insula and the somatosensory cortex were strongly activated as early as 134 ms after stimulus onset. The right inferior parietal lobe seems to be involved in self-referential processing in general. © 2007.

146. Duru, A.D. and A. Ademoglu, Source localization of subtopographies decomposed by radial basis functions. Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2008. 5128 LNCS: p. 108-115.

Summary: Functional neuroimaging methods give the opportunity of investigating human brain functioning. Mostly used functional neuroimaging techniques include Electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and optical imaging. Among these techniques EEG has the best time resolution, while fMRI has the best spatial resolution. High temporal resolution of EEG is an attractive property for neuroimaging studies. EEG inverse problem is needed to be solved in order to identify the locations and the strength of the electrical sources forming EEG/ERP topographies. Low spatial resolution of the scalp topography causes this localization problem more complicated. In this paper, a spatial preprocessing method, which separates a topography into two or more subtopographies is proposed. The decomposition procedure is based on defining a spatial map with radial basis functions which forms the subtopographies. A simulated data is used to exhibit the advantage of using this decomposition technique prior to EEG source localization. It is shown that the accuracy of the source localization problem is improved by using the subtopographies instead of using the raw topography. © 2008 Springer-Verlag Berlin Heidelberg.

147. Doppelmayr, M., T. Finkenzeller, and P. Sauseng, Frontal midline theta in the pre-shot phase of rifle shooting: Differences between experts and novices. Neuropsychologia, 2008. 46(5): p. 1463-1467.

Summary: In the present study the time course of frontal midline theta (Fmθ) during the aiming period in rifle shooting was investigated. Experts (n = 8) and novices (n = 10) had to shoot repeatedly while EEG was recorded, and the time course of Fmθ during the aiming period was significantly different between the two groups, showing a steady increase of power for the last 3 s before the shot only for experts, but not for novices. Source analysis (LORETA) indicated a significantly stronger theta activity for experts strictly located at the anterior cingulate area and medial frontal cortex, locations well known for focused attention. The results suggest that experts and novices use different strategies during the aiming period. While novices keep a relatively constant amount of attention to the target, experts are able to increase attention exactly to the time point of the trigger pull. © 2008 Elsevier Ltd. All rights reserved.

148. Ding, L. and B. He, Sparse source imaging in electroencephalography with accurate field modeling. Human Brain Mapping, 2008. 29(9): p. 1053-1067.

Summary: We have developed a new L1-norm based generalized minimum norm estimate (GMNE) and have fully characterized the concept of sparseness regularization inherited in the proposed algorithm, which is termed as sparse source imaging (SSI). The new SSI algorithm corrects inaccurate source field modeling in previously reported L1-norm GMNEs and proposes that sparseness a priori should only be applied to the regularization term, not to the data term in the formulation of the regularized inverse problem. A new solver to the newly developed SSI has been adopted and known as the second-order cone programming. The new SSI is assessed by a series of simulations and then evaluated using somatosensory evoked potential (SEP) data with both scalp and subdural recordings in a human subject. The performance of SSI is compared with other L1-norm GMNEs and L2-norm GMNEs using three evaluation metrics, i.e., localization error, orientation error, and strength percentage. The present simulation results indicate that the new SSI has significantly improved performance in all evaluation metrics, especially in the metric of orientation error. L2-norm GMNEs show large orientation errors because of the smooth regularization. The previously reported L1-norm GMNEs show large orientation errors due to the inaccurate source field modeling. The SEP source imaging results indicate that SSI has the best accuracy in the prediction of subdural potential field as validated by direct subdural recordings. The new SSI algorithm is also applicable to MEG source imaging. © 2007 Wiley-Liss, Inc.

149. Ding, L., A novel sparse source imaging in reconstructing extended cortical current sources. Proceedings of the 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08 - "Personalized Healthcare through Technology", 2008: p. 4555-4558.

Summary: We have developed a new sparse source imaging (SSI) method with the use of the Ll-norm in EEG inverse problems to reconstruct extended cortical current sources. The new SSI method explores the sparseness in cortical current density variation maps (the transform domain) other than in the cortical current density maps (the original domain) from previously reported SSI methods. The new SSI is assessed by a series of computer simulations. The performance of SSI is compared with the well-known L2-norm MNE using the AUC metric. Our present simulation data indicate that the new SSI has significantly improved performance in reconstructing extended cortical current sources and estimating their cortical extents. The L2-norm MNE shows relatively poor performance in the same source imaging tasks. The new SSI method is also applicable to MEG source imaging. © 2008 IEEE.

150. Diaconescu, A.O., N. Kovacevic, and A.R. McIntosh, Modality-independent processes in cued motor preparation revealed by cortical potentials. NeuroImage, 2008. 42(3): p. 1255-1265.

Summary: We used event-related potentials (ERPs) in a crossmodal stimulus-response compatibility paradigm to identify modality-independent aspects of rule processing and cued response facilitation. Participants responded to a lateralized target with the ipsilateral (compatible) or contralateral (incompatible) hand. Cue-target modality and cue-target order were manipulated. The cue preceded the target in half of the trials, and the target preceded the cue in the other half. For half of the participants, a visual cue signalled the response rule to an auditory target, while in other half, an auditory cue signalled the response rule to a visual target. Behavioural results showed a significant cue facilitation effect with response times faster for trials when the cue preceded the target, regardless of cue-target modality. The overall fastest response times were obtained in auditory cue-visual target trials. We performed groupwise independent component analysis of the cortical potentials and identified two modality-independent spatiotemporal patterns related to experimental effects. The first pattern, which resembled the early part of a contingent-negative waveform, was associated with response rule processing, regardless of cue-target presentation order and modality. The second pattern showed amplitude modulations that were dependent on stimulus modality. However, this pattern also correlated with faster response times only when the cue preceded the target and regardless of cue-target modality. Source analysis suggested that the response rule processing pattern originated from the posterior parietal, motor and cingulate regions. The pattern associated with the cue-first facilitation effect originated from cingulate and medial frontal regions. The effects carried by both patterns showed temporal overlap in the interval between the first and second stimulus presentation, but with differences in their relation to response rule processing and behavioural facilitation. © 2008 Elsevier Inc. All rights reserved.

151. Dhar, M., P.H. Been, R.B. Minderaa, and M. Althaus, Distinct information processing characteristics in dyslexia and ADHD during a covert orienting task: An event-related potential study. Clinical Neurophysiology, 2008. 119(9): p. 2011-2025.

Summary: Objective: A visuo-spatial orienting task was used to investigate the individual and joint contribution of the presence of dyslexia and attention-deficit hyperactivity disorder (ADHD) to information processing. Methods: Sixteen control, 17 dyslexic, 16 ADHD, and 15 comorbid adults performed the task, comprising a valid, invalid, and no-cue condition. Performance measures were errors and reaction time (RT). A negative potential in response to cues and targets (N2), and a positive potential in response to targets (P3) were derived from the EEG. A 2 × 2 design was used with the factors dyslexic/non-dyslexic, and ADHD/non-ADHD. Results: Dyslexic participants demonstrated a smaller cue-related N2, yet a greater target-related N2 in the valid condition. ADHD participants were discriminated by the P3 difference between the invalid and valid conditions. Comorbids differed from ADHD mainly in invalid-valid RT, and were similar to dyslexics in target N2 processing. Conclusions: Dyslexics were impaired in early information processing, and participants with ADHD differed for later processing stages. Significance: This is the first ERP study of attentional processes in dyslexia to incorporate an ADHD and a comorbid group. Its results may contribute to differentiation of these clinical groups. © 2008 International Federation of Clinical Neurophysiology.

152. Desseilles, M., T. Dang-Vu, M. Schabus, V. Sterpenich, P. Maquet, and S. Schwartz, Neuroimaging insights into the pathophysiology of sleep disorders. Sleep, 2008. 31(6): p. 777-794.

Summary: Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might improve our understanding of the pathophysiology underlying adult sleep disorders. Here we review functional brain imaging findings in major intrinsic sleep disorders (i.e., idiopathic insomnia, narcolepsy, and obstructive sleep apnea) and in abnormal motor behavior during sleep (i.e., periodic limb movement disorder and REM sleep behavior disorder). The studies reviewed include neuroanatomical assessments (voxel-based morphometry, magnetic resonance spectroscopy), metabolic/functional investigations (positron emission tomography, single photon emission computed tomography, functional magnetic resonance imaging), and ligand marker measurements. Based on the current state of the research, we suggest that brain imaging is a useful approach to assess the structural and functional correlates of sleep impairments as well as better understand the cerebral consequences of various therapeutic approaches. Modern neuroimaging techniques therefore provide a valuable tool to gain insight into possible pathophysiological mechanisms of sleep disorders in adult humans.

153. Crevecoeur, G., H. Hallez, P. Van Hese, Y. D'Asseler, L. Dupré, and R. Van de Walle, EEG source analysis using space mapping techniques. Journal of Computational and Applied Mathematics, 2008. 215(2): p. 339-347.

Summary: The electroencephalogram (EEG) measures potential differences, generated by electrical activity in brain tissue, between scalp electrodes. The EEG potentials can be calculated by the quasi-static Poisson equation in a certain head model. It is well known that the electrical dipole (source) which best fits the measured EEG potentials is obtained by an inverse problem. The dipole parameters are obtained by finding the global minimum of the relative residual energy (RRE). For the first time, the space mapping technique (SM technique) is used for minimizing the RRE. The SM technique aims at aligning two different simulation models: a fine model, accurate but CPU-time expensive, and a coarse model, computationally fast but less accurate than the fine one. The coarse model is a semi-analytical model, the so-called three-shell concentric sphere model. The fine model numerically solves the Poisson equation in a realistic head model. If we use the aggressive space mapping (ASM) algorithm, the errors on the dipole location are too large. The hybrid aggressive space mapping (HASM) on the other hand has better convergence properties, yielding a reduction in dipole location errors. The computational effort of HASM is greater than ASM but smaller than using direct optimization techniques. © 2007 Elsevier B.V. All rights reserved.

154. Crevecoeur, G., H. Hallez, P. Van Hese, Y. D'Asseler, L. Dupré, and R. Van de Walle, A hybrid algorithm for solving the EEG inverse problem from spatio-temporal EEG data. Medical and Biological Engineering and Computing, 2008. 46(8): p. 767-777.

Summary: Epilepsy is a neurological disorder caused by intense electrical activity in the brain. The electrical activity, which can be modelled through the superposition of several electrical dipoles, can be determined in a non-invasive way by analysing the electro-encephalogram. This source localization requires the solution of an inverse problem. Locally convergent optimization algorithms may be trapped in local solutions and when using global optimization techniques, the computational effort can become expensive. Fast recovery of the electrical sources becomes difficult that way. Therefore, there is a need to solve the inverse problem in an accurate and fast way. This paper performs the localization of multiple dipoles using a global-local hybrid algorithm. Global convergence is guaranteed by using space mapping techniques and independent component analysis in a computationally efficient way. The accuracy is locally obtained by using the Recursively Applied and Projected-MUltiple Signal Classification (RAP-MUSIC) algorithm. When using this hybrid algorithm, a four times faster solution is obtained. © International Federation for Medical and Biological Engineering 2008.

155. Coutin-Churchman, P. and R. Moreno, Intracranial current density (LORETA) differences in QEEG frequency bands between depressed and non-depressed alcoholic patients. Clinical Neurophysiology, 2008. 119(4): p. 948-958.

Summary: Objective: To assess possible differences in intracranial source distribution of surface QEEG power between depressed and non-depressed alcoholic patients in order to find any symptom-related topographic features of physiopathologic relevance. Methods: Low-Resolution Electromagnetic Tomography (LORETA) for the delta, theta, alpha and beta bands of EEG spectra was estimated from 38 alcoholic patients, 20 with and 18 without clinical depression, in which QEEG showed decreased slow and increased beta activity diffusely. Statistical non-parametric mapping was used to compare depressed and non-depressed groups. Measures of intracranial current density in individual patients at areas of significant differences were correlated with BDI scores. Results: Patients with clinical depression showed areas of significantly lower current density than non-depressed patients in delta band at left anterior temporal, left midtemporal (including amygdala and hippocampus), and both frontopolar cortices mostly on the right; and in theta band at bilateral parietal lobe, anterior cingulate and medial frontal cortex. No differences were found at alpha and beta band. Intracranial current density in delta band at left parahippocampal, left midfrontal cortex and right frontopolar cortex was negatively correlated with BDI score. Theta band also showed negative correlations with BDI at sites of significant differences. Conclusions: Diffusely decreased delta and theta activity in the surface QEEG of alcoholic patients has a different intracranial distribution linked to the presence or not of clinical depression that seems to reveal a dysfunctional neuronal state at several specific limbic and other cortical locations that have been related to a specific clinical disorder such as depression. Significance: These results provided further evidence on the effects of depression in the context of alcohol dependence, in this case decreased slow activity as a possible marker of neuronal damage secondary to alcohol toxicity, clinically expressed as depressive symptoms when present in structures that are known to be related to clinical depression. © 2008 International Federation of Clinical Neurophysiology.

156. Cosandier-Rimélé, D., I. Merlet, J.M. Badier, P. Chauvel, and F. Wendling, The neuronal sources of EEG: Modeling of simultaneous scalp and intracerebral recordings in epilepsy. NeuroImage, 2008. 42(1): p. 135-146.

Summary: In many applications which make use of EEG to investigate brain functions, a central question is often to relate the recorded signals to the spatio-temporal organization of the underlying neuronal sources of activity. A modeling attempt to quantitatively investigate this imperfectly known relationship is reported. The proposed plausible model of EEG generation relies on an accurate representation of the neuronal sources of activity. It combines both an anatomically realistic description of the spatial features of the sources (convoluted dipole layer) and a physiologically relevant description of their temporal activities (coupled neuronal populations). The model was used in the particular context of epileptiform activity (interictal spikes) to interpret simultaneously generated scalp and intracerebral EEG. Its integrative properties allowed for the bridging between source-related parameters (spatial extent, location, synchronization) and the properties of resulting EEG signals (amplitude of spikes, amplitude gradient along intracerebral electrodes, topography over scalp electrodes). The sensitivity of both recording modalities to source-related parameters was also studied. The model confirmed that the cortical area involved in interictal spikes is rather large. Its relative location with respect to recording electrodes was found to strongly influence the properties of EEG signals as the source geometry is a critical parameter. The influence, on simulated signals, of the synchronization degree between neuronal populations within the epileptic source was also investigated. The model revealed that intracerebral EEG can reflect epileptic activities corresponding to weak synchronization between neuronal populations of the epileptic patch. These results, as well as the limitations of the model, are discussed. © 2008 Elsevier Inc. All rights reserved.

157. Clemens, B., P. Piros, M. Bessenyei, M. Tóth, K. Hollódy, and I. Kondákor, Imaging the cortical effect of lamotrigine in patients with idiopathic generalized epilepsy: A low-resolution electromagnetic tomography (LORETA) study. Epilepsy Research, 2008. 81(2-3): p. 204-210.

Summary: Purpose: Anatomical localization of the cortical effect of lamotrigine (LTG) in patients with idiopathic generalized epilepsy (IGE). Methods: 19 patients with untreated IGE were investigated. EEG was recorded in the untreated condition and 3 months later when LTG treatment abolished the seizures. 19-channel EEG was recorded, and a total of 2 min artifact-free, waking EEG was processed to low-resolution electromagnetic tomography (LORETA) analysis. Activity (that is, current source density, A/m2) was computed in four frequency bands (delta, theta, alpha, and beta), for 2394 voxels that represented the cortical gray matter and the hippocampi. Group differences between the untreated and treated conditions were computed for the four bands and all voxels by multiple t-tests for interdependent datasets. The results were presented in terms of anatomical distribution and statistical significance. Results: p < 0.01 (uncorrected) changes (decrease of activity) emerged in the theta and the alpha bands. Theta activity decreased in a large cluster of voxels including parts of the temporal, parietal, occipital cortex bilaterally, and in the transverse temporal gyri, insula, hippocampus, and uncus on the right side. Alpha activity decreased in a relatively smaller cortical area involving the right temporo-parietal junction and surrounding parts of the cortex, and part of the insula on the right side. Conclusions: LTG decreased theta activity in several cortical areas where abnormally increased theta activity had been found in a prior study in another cohort of untreated IGE patients [Clemens, B., Bessenyei, M., Piros, P., Tóth, M., Seress, L., Kondákor, I., 2007b. Characteristic distribution of interictal brain electrical activity in idiopathic generalized epilepsy. Epilepsia 48, 941-949]. These LTG-related changes might be related to the decrease of seizure propensity in IGE. © 2008 Elsevier B.V. All rights reserved.

158. Clemens, B., J. Bánk, P. Piros, M. Bessenyei, S. Veto, M. Tóth, and I. Kondákor, Three-dimensional localization of abnormal EEG activity in migraine: A low resolution electromagnetic tomography (LORETA) study of migraine patients in the pain-free interval. Brain Topography, 2008. 21(1): p. 36-42.

Summary: Investigating the brain of migraine patients in the pain-free interval may shed light on the basic cerebral abnormality of migraine, in other words, the liability of the brain to generate migraine attacks from time to time. Twenty unmedicated "migraine without aura" patients and a matched group of healthy controls were investigated in this explorative study. 19-channel EEG was recorded against the linked ears reference and was on-line digitized. 60 × 2-s epochs of eyes-closed, waking-relaxed activity were subjected to spectral analysis and a source localization method, low resolution electromagnetic tomography (LORETA). Absolute power was computed for 19 electrodes and four frequency bands (delta: 1.5-3.5 Hz, theta: 4.0-7.5 Hz, alpha: 8.0-12.5 Hz, beta: 13.0-25.0 Hz). LORETA "activity" (=current source density, ampers/meters squared) was computed for 2394 voxels and the above specified frequency bands. Group comparison was carried out for the specified quantitative EEG variables. Activity in the two groups was compared on a voxel-by-voxel basis for each frequency band. Statistically significant (uncorrected P < 0.01) group differences were projected to cortical anatomy. Spectral findings: there was a tendency for more alpha power in the migraine that in the control group in all but two (F4, C3) derivations. However, statistically significant (P < 0.01, Bonferroni-corrected) spectral difference was only found in the right occipital region. The main LORETA-finding was that voxels with P < 0.01 differences were crowded in anatomically contiguous cortical areas. Increased alpha activity was found in a cortical area including part of the precuneus, and the posterior part of the middle temporal gyrus in the right hemisphere. Decreased alpha activity was found bilaterally in medial parts of the frontal cortex including the anterior cingulate and the superior and medial frontal gyri. Neither spectral analysis, nor LORETA revealed statistically significant differences in the delta, theta, and beta bands. LORETA revealed the anatomical distribution of the cortical sources (generators) of the EEG abnormalities in migraine. The findings characterize the state of the cerebral cortex in the pain-free interval and might be suitable for planning forthcoming investigations. © 2008 Springer Science+Business Media, LLC.

159. Chiu, P.H., A.J. Holmes, and D.A. Pizzagalli, Dissociable recruitment of rostral anterior cingulate and inferior frontal cortex in emotional response inhibition. NeuroImage, 2008. 42(2): p. 988-997.

Summary: The integrity of decision-making under emotionally evocative circumstances is critical to navigating complex environments, and dysfunctions in these processes may play an important role in the emergence and maintenance of various psychopathologies. The goal of the present study was to examine the spatial and temporal dynamics of neural responses to emotional stimuli and emotion-modulated response inhibition. High-density event-related brain potentials (ERPs) were measured as participants (N = 25) performed an emotional Go/NoGo task that required button presses to words of a "target" emotional valence (i.e., positive, negative, neutral) and response inhibition to words of a different "distractor" valence. Using scalp ERP analyses in conjunction with source-localization techniques, we identified distinct neural responses associated with affective salience and affect-modulated response inhibition, respectively. Both earlier (~ 300 ms) and later (~700 ms) ERP components were enhanced with successful response inhibition to emotional distractors. Only ERPs to target stimuli differentiated affective from neutral cues. Moreover, source localization analyses revealed right ventral lateral prefrontal cortex (VLPFC) activation in affective response inhibition regardless of emotional valence, whereas rostral anterior cingulate activation (rACC) was potentiated by emotional valence but was not modulated by response inhibition. This dissociation was supported by a significant Region × Trial Type × Emotion interaction, confirming that distinct regional dynamics characterize neural responses to affective valence and affective response-inhibition. The results are discussed in the context of an emerging affective neuroscience literature and implications for understanding psychiatric pathologies characterized by a detrimental susceptibility to emotional cues, with an emphasis on major depressive disorder. © 2008 Elsevier Inc. All rights reserved.

160. Chan, A.S., Y.M.Y. Han, and M.C. Cheung, Electroencephalographic (EEG) measurements of mindfulness-based triarchic body-pathway relaxation technique: A pilot study. Applied Psychophysiology Biofeedback, 2008. 33(1): p. 39-47.

Summary: Objective: The "Triarchic body-pathway relaxation technique" (TBRT) is a form of ancient Chinese mindfulness-based meditation professed to give rise to positive emotions and a specific state of consciousness in which deep relaxation and internalized attention coexist. The purpose of this study was to examine the EEG pattern generated during the practice of this mindfulness exercise, and compare it to music listening which has been shown to induce positive emotions. Methods: Nineteen college students (aged 19-22 years) participated in the study. Each participant listened to both the TBRT and music audiotapes while EEG was recorded. The order of presentation was counterbalanced to avoid order effect. Two EEG indicators were used: (1) alpha asymmetry index, an indicator for left-sided anterior activation, as measure of positive emotions, and (2) frontal midline theta activity, as a measure for internalized attention. Results: Increased left-sided activation, a pattern associated with positive emotions, was found during both TBRT exercise and music conditions. However, only TBRT exercise was shown to exhibit greater frontal midline theta power, a pattern associated with internalized attention. Conclusions: These results provided evidence to support that the TBRT gives rise to positive emotional experience, accompanied by focused internalized attention. © 2008 Springer Science+Business Media, LLC.

161. Casarotto, S., A.M. Bianchi, E. Ricciardi, C. Gentili, N. Vanello, M. Guazzelli, P. Pietrini, G.A. Chiarenza, and S. Cerutti, Spatiotemporal dynamics of single-letter reading: A combined ERP-FMRI study. Archives Italiennes de Biologie, 2008. 146(2): p. 83-105.

Summary: This work investigates the neural correlates of single-letter reading by combining event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), thus exploiting their complementary spatiotemporal resolutions. Three externally-paced reading tasks were administered with an event-related design: passive observation of letters and symbols and active reading aloud of letters. ERP and fMRI data were separately recorded from 8 healthy adults during the same experimental conditions. Due to the presence of artifacts in the EEG signals, two subjects were discarded from further analysis. Independent Component Analysis was applied to ERPs, after dimensionality reduction by Principal Component Analysis: some independent components were clearly related to specific reading functions and the associated current density distributions in the brain were estimated with Low Resolution Electromagnetic Tomography Analysis method (LORETA). The impulse hemodynamic response function was modeled as a linear combination of linear B-spline functions and fMRI statistical analysis was performed by multiple linear regression. fMRI and LORETA maps were superimposed in order to identify the overlapping activations and the activated regions specifically revealed by each modality. The results showed the existence of neuronal networks functionally specific for letter processing and for explicit verbal-motor articulation, including the temporo-parietal and frontal regions. Overlap between fMRI and LORETA results was observed in the inferior temporal-middle occipital gyrus, suggesting that this area has a crucial and multifunctional role for linguistic and reading processes, likely because its spatial location and strong interconnection with the main visual and auditory sensory systems may have favored its specialization in grapheme-phoneme matching.

162. Cannon, R., J. Lubar, and D. Baldwin, Self-perception and experiential schemata in the addicted brain. Applied Psychophysiology Biofeedback, 2008. 33(4): p. 223-238.

Summary: This study investigated neurophysiological differences between recovering substance abusers (RSA) and controls while electroencephalogram (EEG) was continuously recorded during completion of a new assessment instrument. The participants consisted of 56 total subjects; 28 RSA and 28 non-clinical controls (C). The participants completed the self-perception and experiential schemata assessment (SPESA) and source localization was compared utilizing standardized low-resolution electromagnetic tomography (sLORETA). The data show significant differences between groups during both the assessment condition and baselines. A pattern of alpha activity as estimated by sLORETA was shown in the right amygdala, uncus, hippocampus, BA37, insular cortex and orbitofrontal regions during the SPESA condition. This activity possibly reflects a circuit related to negative perceptions of self formed in specific neural pathways. These pathways may be responsive to the alpha activity induced by many substances by bringing the brain into synchrony if only for a short time. In effect this may represent the euphoria described by substance abusers. © 2008 Springer Science+Business Media, LLC.

163. Brosch, T., D. Sander, G. Pourtois, and K.R. Scherer, Beyond fear: Rapid spatial orienting toward positive emotional stimuli: Research article. Psychological Science, 2008. 19(4): p. 362-370.

Summary: There is much empirical evidence for modulation of attention by negative - particularly fear-relevant - emotional stimuli. This modulation is often explained in terms of a fear module. Appraisal theories of emotion posit a more general mechanism, predicting attention capture by stimuli that are relevant for the needs and goals of the organism, regardless of valence. To examine the brain-activation patterns underlying attentional modulation, we recorded event-related potentials from 20 subjects performing a dot-probe task in which the cues were fear-inducing and nurturance-inducing stimuli (i.e., anger faces and baby faces). Highly similar validity modulation was found for the P1 time-locked to target onset, indicating early attentional capture by both positive and negative emotional stimuli. Topographic segmentation analysis and source localization indicate that the same amplification process is involved whether attention orienting is triggered by negative, fear-relevant stimuli or positive, nurturance-relevant stimuli. These results confirm that biological relevance, and not exclusively fear, produces an automatic spatial orienting toward the location of a stimulus. Copyright © 2008 Association for Psychological Science.

164. Brookes, M.J., K.J. Mullinger, C.M. Stevenson, P.G. Morris, and R. Bowtell, Simultaneous EEG source localisation and artifact rejection during concurrent fMRI by means of spatial filtering. NeuroImage, 2008. 40(3): p. 1090-1104.

Summary: The simultaneous application of functional MRI and EEG represents an attractive, non-invasive technique for the combined measurement of electrical and haemodynamic activity in the human brain. Simultaneous EEG/fMRI provides a brain imaging modality with millimeter spatial accuracy, and millisecond temporal resolution. However, simultaneously acquired measurements are difficult due to the artifacts that are induced in the EEG by both the temporally varying field gradients used in MRI, and also blood flow effects. In this paper we apply an EEG beamformer spatial filter to EEG data recorded simultaneously with fMRI. We show, using this technique, that it is possible to localise accurately electrical effects in the brain, and that the localisation of driven oscillatory responses in the human visual cortex are spatially co-incident with the fMRI BOLD response. We also show how the beamformer can be used to extract timecourses of electrical activity from areas of interest in the brain. Such timecourses have millisecond time resolution. Finally, we show that in addition to source localisation, the beamformer spatial filter acts to reject interference in EEG signals, thus increasing the effective signal to noise ratio of electrical measurements. We show that the EEG-beamformer can eliminate effectively the ballistocardiogram artifact as well as residual gradient artifacts that remain in EEG data following correction using averaged artifact subtraction techniques. © 2008.

165. Boyle, Y., W. El-Deredy, E. Martínez Montes, D.E. Bentley, and A.K.P. Jones, Selective modulation of nociceptive processing due to noise distraction. Pain, 2008. 138(3): p. 630-640.

Summary: This study investigates the effects of noise distraction on the different components and sources of laser-evoked potentials (LEPs) whilst attending to either the spatial component (localisation performance task) or the affective component (unpleasantness rating task) of pain. LEPs elicited by CO2 laser stimulation of the right forearm were recorded from 64 electrodes in 18 consenting healthy volunteers. Subjects reported either pain location or unpleasantness, in the presence and absence of distraction by continuous 85 dBa white noise. Distributed sources of the LEP peaks were identified using Low Resolution Electromagnetic Tomography (LORETA). Pain unpleasantness ratings and P2 (430 ms) peak amplitude were significantly reduced by distraction during the unpleasantness task, whereas the localisation ability and the corresponding N1/N2 (310 ms) peak amplitude remained unchanged. Noise distraction (at 310 ms) reduced activation in the anterior cingulate cortex (ACC) and precuneus during attention to localisation and unpleasantness, respectively. This suggests a complimentary role for these two areas in the control of attention to pain. In contrast, activation of the occipital pole and SII were enhanced by noise during the localisation and unpleasantness task, respectively, suggesting that the presence of noise was associated with increased spatial attentional load. This study has shown selective modulation of affective pain processing by noise distraction, indicated by a reduction in the unpleasantness ratings and P2 peak amplitude and associated activity within the medial pain system. These results show that processing of the affective component of pain can be differentially modulated by top-down processes, providing a potential mechanism for therapeutic intervention. © 2008 International Association for the Study of Pain.

166. Blum, J., K. Lutz, R. Pascual-Marqui, K. Murer, and L. Jäncke, Coherent intracerebral brain oscillations during learned continuous tracking movements. Experimental Brain Research, 2008. 185(3): p. 443-451.

Summary: The aim of the present study was to assess changes in electroencephalogram (EEG) phase locking between fronto-parietal areas, including the frontal and parietal motor areas, during audiomotor learning of continuous tracking movements. Subjects learned to turn a steering wheel according to a given trajectory in order to minimise the discrepancy between a changing foreground stimulus (controllable by the subjects) and a constant background stimulus. The results of the present study show that increasing practice of continuous tracking movements that are continuously performed in the presence of auditory feedback is not accompanied by decrease in phase locking between areas involved. Moreover, the study confirms that internally produced movements show enhanced coherent activities compared to externally guided movements and therefore suggests that the motor-parietal network is more engaged during internally produced than externally produced movements. © 2007 Springer-Verlag.

167. Bellebaum, C. and I. Daum, Learning-related changes in reward expectancy are reflected in the feedback-related negativity. European Journal of Neuroscience, 2008. 27(7): p. 1823-1835.

Summary: The feedback-related negativity (FRN) has been hypothesized to be linked to reward-based learning. While many studies have shown that the FRN only occurs in response to unexpected negative outcomes, the relationship between the magnitude of negative prediction errors and FRN amplitude remains a matter of debate. The present study aimed to elucidate this relationship with a new behavioural procedure that allowed subjects to predict precise reward probabilities by learning an explicit rule. Insight into the rule did not only influence subjects' choice behaviour, but also outcome-related event-related potentials. After subjects had learned the rule, the FRN amplitude difference between non-reward and reward mirrored the magnitude of the negative prediction error, i.e. it was larger for less likely negative outcomes. Source analysis linked this effect to the anterior cingulate cortex. P300 amplitude was also modulated by outcome valence and expectancy. It was larger for positive and unexpected outcomes. It remains to be clarified, however, whether the P300 reflects a positive prediction error. © The Authors (2008).

168. Beeli, G., M. Esslen, and L. Jäncke, Time course of neural activity correlated with colored-hearing synesthesia. Cerebral Cortex, 2008. 18(2): p. 379-385.

Summary: Synesthesia is defined as the involuntary and automatic perception of a stimulus in 2 or more sensory modalities (i.e., cross-modal linkage). Colored-hearing synesthetes experience colors when hearing tones or spoken utterances. Based on event-related potentials we employed electric brain tomography with high temporal resolution in colored-hearing synesthetes and nonsynesthetic controls during auditory verbal stimulation. The auditory-evoked potentials to words and letters were different between synesthetes and controls at the N1 and P2 components, showing longer latencies and lower amplitudes in synesthetes. The intracerebral sources of these components were estimated with low-resolution brain electromagnetic tomography and revealed stronger activation in synesthetes in left posterior inferior temporal regions, within the color area in the fusiform gyrus (V4), and in orbitofrontal brain regions (ventromedial and lateral). The differences occurred as early as 122 ms after stimulus onset. Our findings replicate and extend earlier reports with functional magnetic resonance imaging and positron emission tomography in colored-hearing synesthesia and contribute new information on the time course in synesthesia demonstrating the fast and possibly automatic processing of this unusual and remarkable phenomenon. © 2007 The Authors.

169. Baumann, S., M. Meyer, and L. Jäncke, Enhancement of auditory-evoked potentials in musicians reflects an influence of expertise but not selective attention. Journal of Cognitive Neuroscience, 2008. 20(12): p. 2238-2249.

Summary: Instrumental tones and, in some instances, simple sine-wave tones were shown to evoke stronger auditory-evoked responses in musicians compared to nonmusicians. This effect was taken as an example for plasticity in the auditory cortex elicited by training. To date, however, it is unknown whether an enlarged cortical representation for (instrumental) tones or increased neuronal activity provoked by focused attention in musicians accounts for the reported difference. In an attempt to systematically investigate the influence of attention on the processing of simple sine wave and instrumental tones, we compared auditory-evoked potentials recorded from musicians and nonmusicians. During the electroencephalogram recording, the participants were involved in tasks requiring selective attention to specific sound features such as pitch or timbre. Our results demonstrate that the effect of selective attention on the auditory event-related potential (AEP) has a different time course and shows a different topography than the reproduced effect of music expertise at the N1 component or the previously demonstrated effect at the P2 component. N1 peak potentials were unaffected by attention modulation. These results indicate that the effect of music expertise, which was traced by current density mapping to the auditory cortex, is not primarily caused by selective attention, and it supports the view that increased AEPs on tones in musicians reflect an enlarged neuronal representation for specific sound features of these tones. However, independent from the N1-P2 complex, attention evoked an Nd-like negative component in musicians but not in nonmusicians, which suggests that plasticity also affects top-down processes. © 2008 Massachusetts Institute of Technology.

170. Barbati, G., C. Porcaro, A. Hadjipapas, P. Adjamian, V. Pizzella, G.L. Romani, S. Seri, F. Tecchio, and G.R. Barnes, Functional source separation applied to induced visual gamma activity. Human Brain Mapping, 2008. 29(2): p. 131-141.

Summary: Objective of this work was to explore the performance of a recently introduced source extraction method, FSS (Functional Source Separation), in recovering induced oscillatory change responses from extra-cephalic magnetoencephalographic (MEG) signals. Unlike algorithms used to solve the inverse problem, FSS does not make any assumption about the underlying biophysical source model; instead, it makes use of task-related features (functional constraints) to estimate source/s of interest. FSS was compared with blind source separation (BSS) approaches such as Principal and Independent Component Analysis, PCA and ICA, which are not subject to any explicit forward solution or functional constraint, but require source uncorrelatedness (PCA), or independence (ICA). A visual MEG experiment with signals recorded from six subjects viewing a set of static horizontal black/white square-wave grating patterns at different spatial frequencies was analyzed. The beamforming technique Synthetic Aperture Magnetometry (SAM) was applied to localize task-related sources; obtained spatial filters were used to automatically select BSS and FSS components in the spatial area of interest. Source spectral properties were investigated by using Morlet-wavelet time-frequency representations and significant task-induced changes were evaluated by means of a resampling technique; the resulting spectral behaviours in the gamma frequency band of interest (20-70 Hz), as well as the spatial frequency-dependent gamma reactivity, were quantified and compared among methods. Among the tested approaches, only FSS was able to estimate the expected sustained gamma activity enhancement in primary visual cortex, throughout the whole duration of the stimulus presentation for all subjects, and to obtain sources comparable to invasively recorded data. © 2007 Wiley-Liss, Inc.

171. Anderer, P., B. Saletu, M. Wolzt, S. Culic, A. Assandri, F. Nannipieri, S. Rosini, and G.M. Saletu-Zyhlarz, Double-blind, placebo-controlled, multiple-ascending-dose study on the effects of ABIO-08/01, a novel anxiolytic drug, on perception and cognition, utilizing event-related potential mapping and low-resolution brain electromagnetic tomography. Human Psychopharmacology, 2008. 23(3): p. 243-254.

Summary: Early pharmacological studies in animals demonstrated that ABIO-08/01, a new isoxazoline, exerted anxiolytic and anticonvulsant, but also cognition-enhancing properties. Thus, the aim of the present double-blind, placebo-controlled multiple-ascending-dose study was to investigate the effect of the new compound on event-related potentials (ERPs). In a randomized ascending-dose design for phase-1 studies, 16 young healthy male subjects aged 30.2 ± 5.7 years received three ascending drug doses (10, 20, and 40 mg) and placebo for 7 days, with a washout period of 8 days in between. Auditory ERPs were recorded pre-dose and 2 h post-dose on days 1 (acute effect) and 5 (subacute and absolute superimposed effect). Descriptive statistics with one confirmatory statement on P300 latency demonstrated a significant shortening after acute, subacute, and superimposed administration of 40 mg ABIO-08/01. While ERP amplitudes showed only minor effects, low-resolution brain electromagnetic tomography (LORETA) demonstrated that ABIO-08/01 promotes more efficient information processing by reallocating perceptual and cognitive ERP resources. Thus, our ERP studies confirm early pharmacological findings in animals of a cognition-enhancing effect of ABIO-08/01, which is interesting in the context of the anxiolytic mode of action of the compound as its CNS effects are quite different from those of anxiolytic sedatives, such as Copyright © 2008 john Wiley & Sons, Ltd.

172. Alper, K., M. Raghavan, R. Isenhart, B. Howard, W. Doyle, R. John, and L. Prichep, Localizing epileptogenic regions in partial epilepsy using three-dimensional statistical parametric maps of background EEG source spectra. NeuroImage, 2008. 39(3): p. 1257-1265.

Summary: This preliminary study sought to localize epileptogenic regions in patients with partial epilepsy by analysis of interictal EEG activity utilizing variable resolution electromagnetic tomography (VARETA), a three-dimensional quantitative electroencephalographic (QEEG) frequency-domain distributed source modeling technique. The very narrow band (VNB) spectra spanned the frequency range 0.39 Hz to 19.1 Hz, in 0.39 Hz steps. These VNB spectra were compared to normative data and transformed to provide Z-scores for every scalp derivation, and the spatial distributions of the probable EEG generators of the most abnormal values were displayed on slices from a probabilistic MRI atlas. Each voxel was color-coded to represent the significance of the deviation relative to age appropriate normative values. We compared the resulting three-dimensional images to the localization of epileptogenic regions based on invasive intracranial EEG recordings of seizure onsets. The VARETA image indicated abnormal interictal spectral power values in regions of seizure onset identified by invasive monitoring, mainly in delta and theta range (1.5 to 8.0 Hz). The VARETA localization of the most abnormal voxel was congruent with the epileptogenic regions identified by intracranial recordings with regard to hemisphere in all 6 cases, and with regard to lobe in 5 cases. In contrast, abnormal findings with routine EEG agreed with invasive monitoring with regard to hemisphere in 3 cases and with regard to lobe in 2 cases. These results suggest that analysis of background interictal EEG utilizing distributed source models should be investigated further in clinical epilepsy. © 2007 Elsevier Inc. All rights reserved.

173. Alhaj, H.A., A.E. Massey, and R.H. McAllister-Williams, Effects of cortisol on the laterality of the neural correlates of episodic memory. Journal of Psychiatric Research, 2008. 42(12): p. 971-981.

Summary: Alterations in the laterality of cortical activity have been shown in depressive illnesses. One possible pathophysiological mechanism for this is an effect of corticosteroids. We have previously demonstrated that endogenous cortisol concentrations correlate with the asymmetry of cortical activity related to episodic memory in healthy subjects and depressed patients. To further-examine whether this is due to a causal effect of cortisol on the laterality of episodic memory, we studied the effect of exogenous administration of cortisol in healthy subjects. Twenty-three right-handed healthy male volunteers were tested in a double-blind cross-over study. Event-related potentials (ERPs) were recorded during an episodic memory task following a four-day course of 160 mg/day cortisol or placebo. Low-resolution brain electromagnetic tomography (LORETA) was used to identify brain regions involved in the neurocognitive task. Cortisol levels were measured in saliva samples. ERP and LORETA analysis following placebo demonstrated significant left parahippocampal activation associated with successful retrieval. Cortisol led to a decrease in the mean early frontal ERP voltage and an increase in the late right ERP voltage. LORETA suggested this to be due to a significant increased late activation of the right superior frontal gyrus. There was no significant effect of cortisol on episodic memory performance. This study suggests that exogenous cortisol leads to more positive-going waveforms over the right than the left hemisphere, possibly due to increased monitoring of the products of retrieval. The results support the hypothesis of causal effects of cortisol on the laterality of cortical activity occurring during an episodic memory task. © 2007 Elsevier Ltd. All rights reserved.

174. Abe, T., K. Ogawa, H. Nittono, and T. Hori, Neural generators of brain potentials before rapid eye movements during human REM sleep: A study using sLORETA. Clinical Neurophysiology, 2008. 119(9): p. 2044-2053.

Summary: Objective: Brain activity preceding rapid eye movements (REM) during human REM sleep has remained poorly understood. Slow negative brain potential (pre-REM negativity) appears before REMs. Current sources of this potential were investigated to identify brain activity immediately preceding REMs. Methods: In this study, 22 young healthy volunteers (20-25 years old) participated. Polysomnograms were recorded during normal nocturnal sleep. Brain potentials between 200 ms before and 50 ms after the onset of REMs and pseudo-triggers (3000 ms before the onset of REMs) were averaged. Standardized low-resolution brain electromagnetic tomography (sLORETA) was used to estimate current sources of pre-REM negativity. Results: Pre-REM negativity appeared with the maximal amplitude at right prefrontal sites immediately before REMs. However, this negativity did not appear before pseudo-triggers. Current sources of the pre-REM negativity were estimated in the ventromedial prefrontal cortex, uncus, insula, anterior cingulated cortex, basal forebrain, parahippocampal gyrus, premotor cortex and frontal eye field. Conclusions: The pre-REM negativity reflects brain activity coupled with the occurrence of REMs. Results of this study suggest that emotion, memory, and motor-related brain activity might occur before REMs. Significance: Pre-REM negativity is expected to be a psychophysiological index for elucidating functions of REM sleep. © 2008 International Federation of Clinical Neurophysiology.

175. Zouch, W., R. Khemakhem, J. Boughariou, A. Taleb-Ahmed, I. Feki, A.B. Hamida, and P. Derambure, Combining WMN and FOCUSS recursive approach to estimating the current density distribution in the brain. Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2007: p. 598-601.

Summary: In this paper we present a new approach which combines the two methods of cerebral electric activity's localization: "Weighted Minimum Norm" (WMN) and the iterative method "FOCal Underdetermined System Solver" (FOCUSS). Our idea is to use the current density distribution estimated by the WMN method in order to initialize the weighting matrix necessary for the localization with FOCUSS method. We compare the found results with those of the traditional WMN and FOCUSS methods in term of computing time and resolution matrix. The presented results show that our approach gives a good localization of the active sources in the brain. © 2007 IEEE.

176. Zöllig, J., R. West, M. Martin, M. Altgassen, U. Lemke, and M. Kliegel, Neural correlates of prospective memory across the lifespan. Neuropsychologia, 2007. 45(14): p. 3299-3314.

Summary: Overview: Behavioural data reveal an inverted U-shaped function in the efficiency of prospective memory from childhood to young adulthood to later adulthood. However, prior research has not directly compared processes contributing to age-related variation in prospective memory across the lifespan, hence it is unclear whether the same factors explain the 'rise and fall' of prospective remembering from childhood to later adulthood. The present study examined this question using a paradigm that allowed us to consider the behavioural and neural correlates of processes associated with the prospective and retrospective components of prospective memory. Methods: We compared 14 adolescents, 14 young adults, and 14 old adults in a paradigm where the prospective memory task was embedded in a semantic categorization task. Results: The behavioural data revealed an inverted U-shaped function with adolescents and old adults performing poorly relative to young adults. Analyses of the error data revealed that different processes may have contributed to failures of prospective memory in adolescents and older adults. This finding was supported by age differences in ERP-components for cue detection and post-retrieval processes. Additionally, source localization using LORETA revealed different patterns of neural recruitment for adolescents and older adults relative to younger adults. Conclusion: Our findings demonstrate that adolescents and older adults show different patterns of behavioural errors and neural recruitment for successful prospective remembering indicating that different processes may contribute to the 'rise and fall' of prospective memory across the lifespan. © 2007 Elsevier Ltd. All rights reserved.

177. Zhang, Y., U. Hauser, C. Conty, H.M. Emrich, and D.E. Dietrich, Familial risk for depression and P3b component as a possible neurocognitive vulnerability marker. Neuropsychobiology, 2007. 55(1): p. 14-20.

Summary: Objective: Complex genetic mechanisms are involved in the vulnerability to depressive disorders and cognitive dysfunctions found in depression. This study was performed to explore the effect of the familial risk for depression on electrophysiological correlates of attentional functions as demonstrated by an event-related potential (ERP) go/no-go experiment. Methods: The component P3b as an indicator of target detection processing was investigated in two groups of healthy subjects with or without a family history of depression (n = 14 each). An electrophysiological source localization method (LORETA) was employed to allow a neuro-anatomical interpretation for the ERP data. Results: The group with a familial risk for depression showed a reduced P3b amplitude over left temporal areas in contrast to the control group. This two-dimensional effect was associated with a significantly reduced activation of the left middle temporal gyrus. Conclusions: The P3b amplitude decrement might represent a neurocognitive vulnerability marker for the development of depression. Copyright © 2007 S. Karger AG.

178. Zhang, J., T. Guo, Y. Xu, X. Zhao, and L. Yao, Spatiotemporal patterns of ERP based on combined ICA-LORETA analysis. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2007. 6511(PART 2).

Summary: In contrast to the FMRI methods widely used up to now, this method try to understand more profoundly how the brain systems work under sentence processing task map accurately the spatiotemporal patterns of activity of the large neuronal populations in the human brain from the analysis of ERP data recorded on the brain scalp. In this study, an event-related brain potential (ERP) paradigm to record the on-line responses to the processing of sentences is chosen as an example. In order to give attention to both utilizing the ERPs' temporal resolution of milliseconds and overcoming the insensibility of cerebral location ERP sources, we separate these sources in space and time based on a combined method of independent component analysis (ICA) and low-resolution tomography (LORETA) algorithms. ICA blindly separate the input ERP data into a sum of temporally independent and spatially fixed components arising from distinct or overlapping brain or extra-brain sources. And then the spatial maps associated with each ICA component are analyzed, with use of LORETA to uniquely locate its cerebral sources throughout the full brain according to the assumption that neighboring neurons are simultaneously and synchronously activated. Our results show that the cerebral computation mechanism underlies content words reading is mediated by the orchestrated activity of several spatially distributed brain sources located in the temporal, frontal, and parietal areas, and activate at distinct time intervals and are grouped into different statistically independent components. Thus ICA-LORETA analysis provides an encouraging and effective method to study brain dynamics from ERP.

179. Zaehle, T., L. Jancke, and M. Meyer, Electrical brain imaging evidences left auditory cortex involvement in speech and non-speech discrimination based on temporal features. Behavioral and Brain Functions, 2007. 3.

Summary: Background: Speech perception is based on a variety of spectral and temporal acoustic features available in the acoustic signal. Voice-onset time (VOT) is considered an important cue that is cardinal for phonetic perception. Methods: In the present study, we recorded and compared scalp auditory evoked potentials (AEP) in response to consonant-vowel-syllables (CV) with varying voice-onset-times (VOT) and non-speech analogues with varying noise-onset-time (NOT). In particular, we aimed to investigate the spatio-temporal pattern of acoustic feature processing underlying elemental speech perception and relate this temporal processing mechanism to specific activations of the auditory cortex. Results: Results show that the characteristic AEP waveform in response to consonant-vowel-syllables is on a par with those of non-speech sounds with analogue temporal characteristics. The amplitude of the N1a and N1b component of the auditory evoked potentials significantly correlated with the duration of the VOT in CV and likewise, with the duration of the NOT in non-speech sounds. Furthermore, current density maps indicate overlapping supratemporal networks involved in the perception of both speech and non-speech sounds with a bilateral activation pattern during the N1a time window and leftward asymmetry during the N1b time window. Elaborate regional statistical analysis of the activation over the middle and posterior portion of the supratemporal plane (STP) revealed strong left lateralized responses over the middle STP for both the N1a and N1b component, and a functional leftward asymmetry over the posterior STP for the N1b component. Conclusion: The present data demonstrate overlapping spatio-temporal brain responses during the perception of temporal acoustic cues in both speech and non-speech sounds. Source estimation evidences a preponderant role of the left middle and posterior auditory cortex in speech and non-speech discrimination based on temporal features. Therefore, in congruency with recent fMRI studies, we suggest that similar mechanisms underlie the perception of linguistically different but acoustically equivalent auditory events on the level of basic auditory analysis. © 2007 Zaehle et al; licensee BioMed Central Ltd.

180. Yoshimura, M., T. Koenig, S. Irisawa, T. Isotani, K. Yamada, M. Kikuchi, G. Okugawa, T. Yagyu, T. Kinoshita, W. Strik, and T. Dierks, A pharmaco-EEG study on antipsychotic drugs in healthy volunteers. Psychopharmacology, 2007. 191(4): p. 995-1004.

Summary: Rationale: Both psychotropic drugs and mental disorders have typical signatures in quantitative electroencephalography (EEG). Previous studies found that some psychotropic drugs had EEG effects opposite to the EEG effects of the mental disorders treated with these drugs (key-lock principle). Objectives: We performed a placebo-controlled pharmaco-EEG study on two conventional antipsychotics (chlorpromazine and haloperidol) and four atypical antipsychotics (olanzapine, perospirone, quetiapine, and risperidone) in healthy volunteers. We investigated differences between conventional and atypical drug effects and whether the drug effects were compatible with the key-lock principle. Methods: Fourteen subjects underwent seven EEG recording sessions, one for each drug (dosage equivalent of 1 mg haloperidol). In a time-domain analysis, we quantified the EEG by identifying clusters of transiently stable EEG topographies (microstates). Frequency-domain analysis used absolute power across electrodes and the location of the center of gravity (centroid) of the spatial distribution of power in different frequency bands. Results: Perospirone increased duration of a microstate class typically shortened in schizophrenics. Haloperidol increased mean microstate duration of all classes, increased alpha 1 and beta 1 power, and tended to shift the beta 1 centroid posterior. Quetiapine decreased alpha 1 power and shifted the centroid anterior in both alpha bands. Olanzapine shifted the centroid anterior in alpha 2 and beta 1. Conclusions: The increased microstate duration under perospirone and haloperidol was opposite to effects previously reported in schizophrenic patients, suggesting a key-lock mechanism. The opposite centroid changes induced by olanzapine and quetiapine compared to haloperidol might characterize the difference between conventional and atypical antipsychotics. © 2007 Springer-Verlag.

181. Yildiz, G., A.D. Duru, A. Ademoglu, and T. Demiralp, Bayesian EEG dipole source localization using SA-RJMCMC on realistic head model. Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2007: p. 4268-4272.

Summary: In this study, electroencephalography (EEG) inverse problem is formulated using Bayesian inference. The posterior probability distribution of current sources is sampled by Markov Chain Monte Carlo (MCMC) methods. Sampling algorithm is designed by combining Reversible Jump (RJ) which permits trans-dimensional iterations and Simulated Annealing (SA), a heuristic to escape from local optima. Two different approaches to EEG inverse problem, Equivalent Current Dipole (ECD) and Distributed Linear Imaging (DLI) are combined in terms of probability. EEG inverse problem is solved with this probabilistic approach using simulated data on a realistic head model. Localization errors are computed. Comparing to Multiple Signal Classification algorithm (MUSIC) and Low-Resolution Electromagnetic Tomography (LORETA), using MCMC methods with a Bayesian approach is useful for solving the EEG inverse problem. © 2007 IEEE.

182. Xu, P., Y. Tian, H. Chen, and D. Yao, Lp norm iterative sparse solution for EEG source localization. IEEE Transactions on Biomedical Engineering, 2007. 54(3): p. 400-409.

Summary: How to localize the neural electric activities effectively and precisely from the scalp EEG recordings is a critical issue for clinical neurology and cognitive neuroscience. In this paper, based on the spatial sparse assumption of brain activities, proposed is a novel iterative EEG source imaging algorithm, Lp norm iterative sparse solution (LPISS). In LPISS, the lp(p ≤ 1) norm constraint for sparse solution is integrated into the iterative weighted minimum norm solution of the underdetermined EEG inverse problem, and it is the constraint and the iteratively renewed weight that forces the inverse problem to converge to a sparse solution effectively. The conducted simulation studies with comparison to LORETA and FOCUSS for various dipoles configurations confirmed the validation of LPISS for sparse EEG source localization. Finally, LPISS was applied to a real evoked potential collected in a study of inhibition of return (IOR), and the result was consistent with the previously suggested activated areas involved in an IOR process. © 2007 IEEE.

183. Whitford, T.J., C.J. Rennie, S.M. Grieve, C.R. Clark, E. Gordon, and L.M. Williams, Brain maturation in adolescence: Concurrent changes in neuroanatomy and neurophysiology. Human Brain Mapping, 2007. 28(3): p. 228-237.

Summary: Adolescence to early adulthood is a period of dramatic transformation in the healthy human brain. However, the relationship between the concurrent structural and functional changes remains unclear. We investigated the impact of age on both neuroanatomy and neurophysiology in the same healthy subjects (n = 138) aged 10 to 30 years using magnetic resonance imaging (MRI) and resting electroencephalography (EEG) recordings. MRI data were segmented into gray and white matter images and parcellated into large-scale regions of interest. Absolute EEG power was quantified for each lobe for the slow-wave, alpha and beta frequency bands. Gray matter volume was found to decrease across the age bracket in the frontal and parietal cortices, with the greatest change occurring in adolescence. EEG activity, particularly in the slow-wave band, showed a similar curvilinear decline to gray matter volume in corresponding cortical regions. An inverse pattern of curvilinearly increasing white matter volume was observed in the parietal lobe. We suggest that the reduction in gray matter primarily reflects a reduction of neuropil, and that the corresponding elimination of active synapses is responsible for the observed reduction in EEG power. © 2006 Wiley-Liss, Inc.

184. Volpe, U., A. Mucci, P. Bucci, E. Merlotti, S. Galderisi, and M. Maj, The cortical generators of P3a and P3b: A LORETA study. Brain Research Bulletin, 2007. 73(4-6): p. 220-230.

Summary: The P3 is probably the most well known component of the brain event-related potentials (ERPs). Using a three-tone oddball paradigm two different components can be identified: the P3b elicited by rare target stimuli and the P3a elicited by the presentation of rare non-target stimuli. Although the two components may partially overlap in time and space, they have a different scalp topography suggesting different neural generators. The present study is aimed at defining the scalp topography of the two P3 components by means of reference-independent methods and identifying their electrical cortical generators by using the low-resolution electromagnetic tomography (LORETA). ERPs were recorded during a three-tone oddball task in 32 healthy, right-handed university students. The scalp topography of the P3 components was assessed by means of the brain electrical microstates technique and their cortical sources were evaluated by LORETA. P3a and P3b showed different scalp topography and cortical sources. The P3a electrical field had a more anterior distribution as compared to the P3b and its generators were localized in cingulate, frontal and right parietal areas. P3b sources included bilateral frontal, parietal, limbic, cingulate and temporo-occipital regions. Differences in scalp topography and cortical sources suggest that the two components reflect different neural processes. Our findings on cortical generators are in line with the hypothesis that P3a reflects the automatic allocation of attention, while P3b is related to the effortful processing of task-relevant events. © 2007 Elsevier Inc. All rights reserved.

185. Vandervert, L.R., P.H. Schimpf, and H. Liu, How Working Memory and the Cerebellum Collaborate to Produce Creativity and Innovation. Creativity Research Journal, 2007. 19(1): p. 1-18.

Summary: It is proposed that (a) creativity and innovation are the result of continuously repetitive processes of working memory that are learned as cognitive control models in the cerebellum, (b) that these cerebellar control models consist of multiple-paired predictor (forward) models within the MOdular Selection and Identification for Control (MOSAIC) and hierarchical MOSAIC (HMOSAIC) cerebellar architectures that explore and test problem-solving requirements, and (c) when resulting newly formed predictor/controller models are fed forward to more efficiently control the operations of working memory, they lead to creative and innovative problem solving (including the experiences of "insight" and "intuition"). Within this framework, three of Einstein's classic autobiographical accounts of creative discovery are analyzed. It is concluded that the working memory/cerebellar explanation of creativity and innovation can begin to tie together: (1) behavioral and neuroimaging studies of working memory, (2) behavioral, clinical and neuroimaging studies of the cognitive functions of the cerebellum, and (3) autobiographical accounts of creativity. It is suggested that newly developed electromagnetic inverse techniques will be a necessary complement to functional brain imaging studies to further establish the validity of the theory. Copyright © 2007 by Lawrence Erlbaum Associates, Inc.

186. Van Leeuwen, T., P. Been, M. Van Herten, F. Zwarts, B. Maassen, and A. Van Der Leij, Cortical categorization failure in 2-month-old infants at risk for dyslexia. NeuroReport, 2007. 18(9): p. 857-861.

Summary: Cortical auditory categorization was assessed in 2-month-old infants at genetic risk for dyslexia and controls. Manipulated /bAk/ and /dAk/ speech stimuli were used as frequently presented standards. The neuroelectric brain responses of the control infants were highly sensitive to the phoneme boundary that separated these stimuli, but the infants at risk showed no signs of cortical categorical perception. Cortical sources of the responses were predominantly found in the left hemisphere for the control infants, but mainly in the right hemisphere for the infants at risk. The results demonstrate that impaired categorical perception in dyslexia is already present in infants at risk for the disorder. © 2007 Lippincott Williams & Wilkins, Inc.

187. Van De Heyning, P., P. Lefebvre, and D. De Ridder, Tinnitus: From cochlear to cortical. B-ENT, 2007. 3(SUPPL. 7): p. 1-2.

Summary:

188. Tzur, G. and A. Berger, When things look wrong: Theta activity in rule violation. Neuropsychologia, 2007. 45(13): p. 3122-3126.

Summary: A violation of a rule or expectation is known to evoke a phasic negative potential over the medial frontal cortex. This electrophysiological effect has been shown for incorrect mathematical equations and incongruent words at the end of sentences. The cognitive processes elicited in rule violation seem to involve violation of expectation, error detection, and conflict between competing cognitions. Consistent with the conceptual relation between rule violation and error/conflict detection, rule violation conditions should involve a power increase in the theta frequency band involving the anterior cingulate cortex (ACC). The present study verifies the connection between rule violation and theta activity using a wavelet analysis. Moreover, low resolution brain electromagnetic tomography (LORETA) source localization connects this theta activity to the ACC. Furthermore, the results show that theta activity is sensitive to the salience of the violation, that is, the degree of deviation of the conflicting/erroneous stimulus from the correct (expected) one. © 2007 Elsevier Ltd. All rights reserved.

189. Tucker, D.M., M. Brown, P. Luu, and M.D. Holmes, Discharges in ventromedial frontal cortex during absence spells. Epilepsy and Behavior, 2007. 11(4): p. 546-557.

Summary: Neural mechanisms of conscious attention require thalamic control of widespread cortical networks. Absence spells involve a momentary loss of voluntary control of attention, during which the person is inactive and unresponsive. The spike-wave seizure discharges of these spells rapidly engage both cerebral hemispheres in the classic sign of a "generalized" seizure. Animal evidence suggests that spike-wave seizures are caused by a disruption of thalamic circuitry, with extensive spread to cortex through thalamocortical propagation. We applied advanced methods of electrical source analysis to dense array (256-channel) electroencephalographic recordings of spike-wave discharges of absence spells. Neither the onset nor the spread of these seizures is generalized. Rather, the slow waves of the discharges are restricted to frontotemporal networks, and the spikes represent a highly localized and stereotyped progression of electrophysiological activity in ventromedial frontal networks. Given the current knowledge of the neurophysiology of absence seizures, this specificity of the frontal cortical discharges suggests the hypothesis that absence spells are associated with pathology in a circuit comprising ventromedial frontal cortex, rostral thalamic reticular nucleus, and limbic nuclei of the thalamus. Disrupted in absence, this circuit appears to regulate important aspects of the voluntary control of conscious attention. © 2007 Elsevier Inc. All rights reserved.

190. Toth, M., A. Kiss, P. Kosztolanyi, and I. Kondakor, Diurnal alterations of brain electrical activity in healthy adults: A LORETA study. Brain Topography, 2007. 20(2): p. 63-76.

Summary: EEG background activity was investigated by low resolution brain electromagnetic tomography (LORETA) to test the diurnal alterations of brain electrical activity in healthy adults. Fourteen right-handed healthy male postgraduate medical students were examined four times (8 a.m., 2 p.m., 8 p.m. and next day 2 p.m.). LORETA was computed to localize generators of EEG frequency components. Comparing the EEG activity between 2 p.m. and 8 a.m., increased activity was seen (1) in theta band (6.5-8 Hz) in the left prefrontal, bilateral mesial frontal and anterior cingulate cortex; (2) in alpha2 band (10.5-12 Hz) in the bilateral precuneus and posterior parietal cortex as well as in the right temporo-occipital cortex; (3) in beta1-2-3 band (12.5-30 Hz) in the right hippocampus and parieto-occipital cortex, left frontal and bilateral cingulate cortex. Comparing the brain activity between 8 p.m. and 8 a.m., (1) midline theta activity disappeared; (2) increased alpha2 band activity was seen in the left hemisphere (including the left hippocampus); and (3) increased beta bands activity was found over almost the whole cortex (including both of hippocampi) with the exception of left temporo-occipital region. There were no significant changes between the background activities of 2 p.m. and next day 2 p.m. Characteristic distribution of increased activity of cortex (no change in delta band, and massive changes in the upper frequency bands) may mirror increasing activation of reticular formation and thus evoked thalamocortical feedback mechanisms as a sign of maintenance of arousal. © 2007 Springer Science+Business Media, LLC.

191. Stančák, A., H. Poláček, J. Vrána, and J. Mlynář, Cortical oscillatory changes during warming and heating in humans. Neuroscience, 2007. 147(3): p. 842-852.

Summary: Warmth and heat are registered by different types of cutaneous receptors. To disentangle the cortical activation patterns of warming and heating, we analyzed the temporal evolution of the electroencephalographic 10 and 20 Hz oscillations with the time resolution of hundreds of milliseconds. Sixty heat (from 32 to 50.5 °C, rate of change 6 °C/s) and warm (from 32 to 42 °C, 6 °C/s) stimuli were applied on the right thenar using contact thermode. EEG was recorded from 111 scalp electrodes in 12 healthy subjects, and analyzed using event-related desynchronization and low-resolution electromagnetic tomography methods. During warming, the amplitudes of 10 and 20 Hz oscillations over the contralateral primary sensorimotor (SI/MI) and premotor cortices decreased, and the amplitude of 20 Hz oscillations in the anterior cingulate and ipsilateral premotor cortex increased. Heating was associated with additional profound amplitude decreases of 10 and 20 Hz oscillations over SI/MI and premotor cortex, and by amplitude increase of 20 Hz oscillations originating in the posterior cingulate cortex. Results suggest biphasic amplitude changes of the cortical oscillations during ramp increase of temperature attributable to the periods of warming and heating. The amplitude decreases of 10 and 20 Hz oscillations in SI/MI and premotor cortex possibly aid in preparation of motor withdrawal reaction in an event that temperature should reach intolerable pain. Synchronization of the 20 Hz oscillations in the anterior and especially in the posterior cingulate cortex may aid suppression of unwanted movements. © 2007 IBRO.

192. Spyrou, L., S. Sanei, and C.C. Took, Estimation and location tracking of the P300 subcomponents from single-trial EEG. ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, 2007. 2.

Summary: Estimating the P300 subcomponents of Event Related Potentials (ERPs) is very important in the fields of psychiatry and neurology. The characteristics of these brain signals, such as latency, location, strength, and variation, can give useful insights of the person's condition. In particular, the signals' characteristics can aid in the diagnosis and monitoring of some specific psychiatric diseases such as schizophrenia of various stages, and can be a useful factor for their treatment. In this paper we employ a new filtering algorithm, incorporating prior knowledge of the shape of such components. Then we employ a novel localization algorithm to track the location of the P300 components trial by trial. © 2007 IEEE.

193. Sherlin, L., T. Budzynski, H. Kogan Budzynski, M. Congedo, M.E. Fischer, and D. Buchwald, Low-resolution electromagnetic brain tomography (LORETA) of monozygotic twins discordant for chronic fatigue syndrome. NeuroImage, 2007. 34(4): p. 1438-1442.

Summary: Background: Previous work using quantified EEG has suggested that brain activity in individuals with chronic fatigue syndrome (CFS) and normal persons differs. Our objective was to investigate if specific frequency band-pass regions and spatial locations are associated with CFS using low-resolution electromagnetic brain tomography (LORETA). Methods: We conducted a co-twin control study of 17 pairs of monozygotic twins where 1 twin met criteria for CFS and the co-twin was healthy. Twins underwent an extensive battery of tests including a structured psychiatric interview and a quantified EEG. Eyes closed EEG frequency-domain analysis was computed and the entire brain volume was compared of the CFS and healthy twins using a multiple comparison procedure. Results: Compared with their healthy co-twins, twins with CFS differed in current source density. The CFS twins had higher delta in the left uncus and parahippocampal gyrus and higher theta in the cingulate gyrus and right superior frontal gyrus. Conclusions: These findings suggest that neurophysiological activity in specific areas of the brain may differentiate individuals with CFS from those in good health. The study corroborates that slowing of the deeper structures of the limbic system is associated with affect. It also supports the neurobiological model that the right forebrain is associated with sympathetic activity and the left forebrain with the effective management of energy. These preliminary findings await replication. © 2006 Elsevier Inc. All rights reserved.

194. Sauseng, P., J. Hoppe, W. Klimesch, C. Gerloff, and F.C. Hummel, Dissociation of sustained attention from central executive functions: Local activity and interregional connectivity in the theta range. European Journal of Neuroscience, 2007. 25(2): p. 587-593.

Summary: Human brain oscillatory activity was analysed in the electroencephalographic theta frequency range (4-7 Hz) while subjects executed complex sequential finger movements with varying task difficulty and memory load. Local frontal-midline theta activity was associated with the general level of cognitive demand, with the highest amplitudes in the most demanding condition. Using low-resolution electromagnetic tomography analysis (LORETA), this theta activity was localized in the anterior cingulate gyrus including the cingulate motor area. These results suggest that local theta activity in the anterior cingulate gyrus represents correlates of an attentional system that allocate cognitive resources. In addition, interregional connectivity in the theta frequency range was modulated by memory-related executive functions independently of task difficulty. Connectivity analyses revealed a more distributed long-range network including frontal and parietal cortices during execution of novel compared with well-trained finger movement sequences. Thus, these results are compatible with a model in which theta long-range coupling indicates integration of sensory information into executive control components of complex motor behaviour. © The Authors (2007).

195. Sandmann, P., T. Eichele, K. Specht, L. Jäncke, L.M. Rimol, H. Nordby, and K. Hugdahl, Hemispheric asymmetries in the processing of temporal acoustic cues in consonant-vowel syllables. Restorative Neurology and Neuroscience, 2007. 25(3-4): p. 227-240.

Summary: Purpose: In order to examine auditory lateralization of prelexical speech processing, a dichotic listening task was performed with concurrent EEG measurement. Methods: Subjects were tested with dichotic pairs of six consonant-vowel (CV) syllables that initially started with a voiced (/ba/, /da/, /ga/) or a voiceless stop consonant (/pa/, /ta/, /ka/). Electrophysiological correlates were analyzed by a low resolution electromagnetic tomography (LORETA) approach to estimate the sources of N1 event-related potentials (ERP) in the 3D brain. Results: Behavioral and electrophysiological measures revealed different ear advantages and ERP amplitude measures for voiced and voiceless syllables. Fronto-central N1 amplitudes were larger for syllables with voiced than voiceless initial consonants. LORETA source estimates revealed a lateralization effect, with stronger leftward lateralization for voiced than voiceless CV syllables. Conclusions: The present study demonstrates that auditory lateralization is affected by temporal cues in CV syllables. The lateralization effect suggests that functional hemispheric differences exist at an early prelexical level of speech processing. © 2007 - IOS Press and the authors. All rights reserved.

196. Saletu, M., P. Anderer, H.V. Semlitsch, G.M. Saletu-Zyhlarz, M. Mandl, J. Zeitlhofer, and B. Saletu, Low-resolution brain electromagnetic tomography (LORETA) identifies brain regions linked to psychometric performance under modafinil in narcolepsy. Psychiatry Research - Neuroimaging, 2007. 154(1): p. 69-84.

Summary: Low-resolution brain electromagnetic tomography (LORETA) showed a functional deterioration of the fronto-temporo-parietal network of the right hemispheric vigilance system in narcolepsy and a therapeutic effect of modafinil. The aim of this study was to determine the effects of modafinil on cognitive and thymopsychic variables in patients with narcolepsy and investigate whether neurophysiological vigilance changes correlate with cognitive and subjective vigilance alterations at the behavioral level. In a double-blind, placebo-controlled crossover design, EEG-LORETA and psychometric data were obtained during midmorning hours in 15 narcoleptics before and after 3 weeks of placebo or 400 mg modafinil. Cognitive investigations included the Pauli Test and complex reaction time. Thymopsychic/psychophysiological evaluation comprised drive, mood, affectivity, wakefulness, depression, anxiety, the Symptom Checklist 90 and critical flicker frequency. The Multiple Sleep Latency Test (MSLT) and the Epworth Sleepiness Scale (ESS) were performed too. Cognitive performance (Pauli Test) was significantly better after modafinil than after placebo. Concerning reaction time and thymopsychic variables, no significant differences were observed. Correlation analyses revealed that a decrease in prefrontal delta, theta and alpha-1 power correlated with an improvement in cognitive performance. Moreover, drowsiness was positively correlated with theta power in parietal and medial prefrontal regions and beta-1 and beta-2 power in occipital regions. A less significant correlation was observed between midmorning EEG LORETA and the MSLT; between EEG LORETA and the ESS, the correlation was even weaker. In conclusion, modafinil did not influence thymopsychic variables in narcolepsy, but it significantly improved cognitive performance, which may be related to medial prefrontal activity processes identified by LORETA. © 2006 Elsevier Ireland Ltd. All rights reserved.

197. Rossini, P.M., S. Rossi, C. Babiloni, and J. Polich, Clinical neurophysiology of aging brain: From normal aging to neurodegeneration. Progress in Neurobiology, 2007. 83(6): p. 375-400.

Summary: Physiological brain aging is characterized by a loss of synaptic contacts and neuronal apoptosis that provokes age-dependant decline of sensory processing, motor performance, and cognitive function. Neural redundancy and plastic remodelling of brain networking, also secondary to mental and physical training, promotes maintenance of brain activity in healthy elderly for everyday life and fully productive affective and intellectual capabilities. However, age is the main risk factor for neurodegenerative disorders such as Alzheimer's disease (AD) that impact on cognition. Oscillatory electromagnetic brain activity is a hallmark of neuronal network function in various brain regions. Modern neurophysiological techniques including electroencephalography (EEG), event-related potential (ERP), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS) can accurately index normal and abnormal brain aging to facilitate non-invasive analysis of cortico-cortical connectivity and neuronal synchronization of firing and coherence of rhythmic oscillations at various frequencies. The present review provides a perspective of these issues by assaying different neurophysiological methods and integrating the results with functional brain imaging findings. It is concluded that discrimination between physiological and pathological brain aging clearly emerges at the group level, with applications at the individual level also suggested. Integrated approaches utilizing neurophysiological techniques together with biological markers and structural and functional imaging are promising for large-scale, low-cost and non-invasive evaluation of at-risk populations. Practical implications of the methods are emphasized. © 2007 Elsevier Ltd. All rights reserved.

198. Rodriguez, G., C. Babiloni, A. Brugnolo, C. Del Percio, F. Cerro, F. Gabrielli, N. Girtler, F. Nobili, G. Murialdo, P.M. Rossini, D.S. Rossi, C. Baruzzi, and A.M. Ferro, Cortical sources of awake scalp EEG in eating disorders. Clinical Neurophysiology, 2007. 118(6): p. 1213-1222.

Summary: Objective: To investigate quantitative EEG (qEEG) in anorexia nervosa (AN) and bulimia nervosa (BN) in comparison with healthy controls. Methods: Resting EEG was recorded in 30 healthy females (age: 27.1 ± 5.5), 16-AN females (age: 26.4 ± 9.5) and 12-BN females (age: 27.0 ± 6.3). Cortical EEG sources (delta, theta, alpha 1, alpha 2, beta 1, beta 2) were modeled by LORETA solutions. The statistical analysis was performed considering the factors Group, power Band, and region of interest (central, frontal, parietal, occipital, temporal, limbic). Results: Alpha 1 sources in central, parietal, occipital and limbic areas showed a greater amplitude in Controls versus AN and BN groups. Alpha 2 sources in parietal, occipital and limbic areas showed a greater amplitude in Controls than in both AN and BN groups. Alpha 1 sources in temporal area showed a greater amplitude in Controls compared to both the BN and AN groups as well as in the BN group compared to AN group. Central alpha 1 source correlated significantly with BMI in patients. Conclusions: These results support the hypothesis that eating disorders are related to altered mechanisms of cortical neural synchronization, especially in rolandic alpha rhythms. Significance: To our knowledge this is the first study by LORETA able to detect modifications of cortical EEG activity in eating disorders. © 2007 International Federation of Clinical Neurophysiology.

199. Rippon, G., J. Brock, C. Brown, and J. Boucher, Disordered connectivity in the autistic brain: Challenges for the 'new psychophysiology'. International Journal of Psychophysiology, 2007. 63(2): p. 164-172.

Summary: In 2002, we published a paper [Brock, J., Brown, C., Boucher, J., Rippon, G., 2002. The temporal binding deficit hypothesis of autism. Development and Psychopathology 142, 209-224] highlighting the parallels between the psychological model of 'central coherence' in information processing [Frith, U., 1989. Autism: Explaining the Enigma. Blackwell, Oxford] and the neuroscience model of neural integration or 'temporal binding'. We proposed that autism is associated with abnormalities of information integration that is caused by a reduction in the connectivity between specialised local neural networks in the brain and possible overconnectivity within the isolated individual neural assemblies. The current paper updates this model, providing a summary of theoretical and empirical advances in research implicating disordered connectivity in autism. This is in the context of changes in the approach to the core psychological deficits in autism, of greater emphasis on 'interactive specialisation' and the resultant stress on early and/or low-level deficits and their cascading effects on the developing brain [Johnson, M.H., Halit, H., Grice, S.J., Karmiloff-Smith, A., 2002. Neuroimaging of typical and atypical development: a perspective from multiple levels of analysis. Development and Psychopathology 14, 521-536].We also highlight recent developments in the measurement and modelling of connectivity, particularly in the emerging ability to track the temporal dynamics of the brain using electroencephalography (EEG) and magnetoencephalography (MEG) and to investigate the signal characteristics of this activity. This advance could be particularly pertinent in testing an emerging model of effective connectivity based on the balance between excitatory and inhibitory cortical activity [Rubenstein, J.L., Merzenich M.M., 2003. Model of autism: increased ratio of excitation/inhibition in key neural systems. Genes, Brain and Behavior 2, 255-267; Brown, C., Gruber, T., Rippon, G., Brock, J., Boucher, J., 2005. Gamma abnormalities during perception of illusory figures in autism. Cortex 41, 364-376]. Finally, we note that the consequence of this convergence of research developments not only enables a greater understanding of autism but also has implications for prevention and remediation. © 2006.

200. Prox, V., D.E. Dietrich, Y. Zhang, H.M. Emrich, and M.D. Ohlmeier, Attentional processing in adults with ADHD as reflected by event-related potentials. Neuroscience Letters, 2007. 419(3): p. 236-241.

Summary: Attention deficit/hyperactivity disorder (ADHD) is a well known childhood disease and well researched via event-related potentials (ERPs), but unfortunately there is little information on this illness in adults in ERPs. In the present study, 12 adults diagnosed with ADHD and 12 healthy control adults were examined with respect to ERPs in a visual Go/NoGo-experiment to gain information about target evaluation processing in these patients. Two attention-related ERP-components, the N1 and N2 were significantly increased for the ADHD adults compared to the healthy control adults. These findings were illustrated using source analysis results: In the time frame corresponding to the N1, significant increases of activity were found in the medial frontal gyrus and during the N2 time frame significant increases were detected in the lingual gyrus. The P300 showed a tendency towards decreased activity in the patient group, however, only a subsequent slow wave activity indicated significant differences. Neuronal activity related to early attentional mechanisms (N1 and N2) appears to be enhanced in ADHD patients. Together with the finding of a reduction in the P300, the data suggest that ADHD adults have learned to gather their attention more strongly than healthy adults in order to achieve the same results and compensate for their impairment. This is supported by the source analysis results which show activity in additional brain areas. © 2007 Elsevier Ireland Ltd. All rights reserved.

201. Proverbio, A.M., F. Wiedemann, R. Adorni, V. Rossi, M. Del Zotto, and A. Zani, Dissociating object familiarity from linguistic properties in mirror word reading. Behavioral and Brain Functions, 2007. 3.

Summary: Background: It is known that the orthographic properties of linguistic stimuli are processed within the left occipitotemporal cortex at about 150-200 ms. We recorded event-related potentials (ERPs) to words in standard or mirror orientation to investigate the role of visual word form in reading. Word inversion was performed to determine whether rotated words lose their linguistic properties. Methods: About 1300 Italian words and legal pseudo-words were presented to 18 right-handed Italian students engaged in a letter detection task. EEG was recorded from 128 scalp sites. Results: ERPs showed an early effect of word orientation at ∼150 ms, with larger N1 amplitudes to rotated than to standard words. Low-resolution brain electromagnetic tomography (LORETA) revealed an increase in N1 to rotated words primarily in the right occipital lobe (BA 18), which may indicate an effect of stimulus familiarity. N1 was greater to target than to non-target letters at left lateral occipital sites, thus reflecting the first stage of orthographic processing. LORETA revealed a strong focus of activation for this effect in the left fusiform gyrus (BA 37), which is consistent with the so-called visual word form area (VWFA). Standard words (compared to pseudowords) elicited an enhancement of left occipito/temporal negativity at about 250-350 ms, followed by a larger anterior P3, a reduced frontal N400 and a huge late positivity. Lexical effects for rotated strings were delayed by about 100 ms at occipito/temporal sites, and were totally absent at later processing stages. This suggests the presence of implicit reading processes, which were pre-attentive and of perceptual nature for mirror strings. Conclusion: The contrast between inverted and standard words did not lead to the identification of a purely linguistic brain region. This finding suggests some caveats in the interpretation of the inversion effect in subtractive paradigms. © 2007 Proverbio et al; licensee BioMed Central Ltd.

202. Pratt, H., A. Starr, H.J. Michalewski, N. Bleich, and N. Mittelman, The N1 complex to gaps in noise: Effects of preceding noise duration and intensity. Clinical Neurophysiology, 2007. 118(5): p. 1078-1087.

Summary: Objective: To study the effects of duration and intensity of noise that precedes gaps in noise on the N-Complex (N1a and N1b) of Event-Related Potentials (ERPs) to the gaps. Methods: ERPs were recorded from 13 normal subjects in response to 20 ms gaps in 2-4.5 s segments of binaural white noise. Within each segment, the gaps appeared after 500, 1500, 2500 or 4000 ms of noise. Noise intensity was either 75, 60 or 45 dBnHL. Analysis included waveform peak measurements and intracranial source current density estimations, as well as statistical assessment of the effects of pre-gap noise duration and intensity on N1a and N1b and their estimated intracranial source activity. Results: The N-Complex was detected at about 100 ms under all stimulus conditions. Latencies of N1a (at ∼90 ms) and N1b (at ∼150 ms) were significantly affected by duration of the preceding noise. Both their amplitudes and the latency of N1b were affected by the preceding noise intensity. Source current density was most prominent, under all stimulus conditions, in the vicinity of the temporo-parietal junction, with the first peak (N1a) lateralized to the left hemisphere and the second peak (N1b) - to the right. Additional sources with lower current density were more anterior, with a single peak spanning the duration of the N-Complex. Conclusions: The N1a and N1b of the N-Complex of the ERPs to gaps in noise are affected by both duration and intensity of the pre-gap noise. The minimum noise duration required for the appearance of a double-peaked N-Complex is just under 500 ms, depending on noise intensity. N1a and N1b of the N-Complex are generated predominantly in opposite temporo-parietal brain areas: N1a on the left and N1b on the right. Significance: Duration and intensity interact to define the dual peaked N-Complex, signaling the cessation of an ongoing sound. © 2007.

203. Pinto, B. and C.Q. Silva, A simple method for calculating the depth of EEG sources using minimum norm estimates (MNE). Medical and Biological Engineering and Computing, 2007. 45(7): p. 643-652.

Summary: Neural source localization using electroencephalographic data is usually performed using either dipolar models or minimum norm based techniques. While the former demands a priori information about the number of active sources and is particularly suitable for generators, which occupy small pieces of cortical tissue, the major drawbacks of the second approach are its dependence on the uncorrelated noise, and its tendency to localize the sources at the surface. In this paper, a simple mathematical procedure, based on the behavior of the dispersion of the minimum norm solutions, is introduced, in order to estimate the depth of the sources. The correct position of the active generators is obtained using successively deeper surfaces instead of the application of a regularization matrix, as is commonly described in the bibliography. The evaluation of this technique is performed using single and double dipolar simulated generators and two different models for the head: spherical and realistic. The results yield a mean accuracy of about 10 mm for the most disadvantageous situations studied and thus, this method seems to be very promising to handle the depth of the neural generators. © International Federation for Medical and Biological Engineering 2007.

204. Penny, W., G. Flandin, and N. Trujillo-Barreto, Bayesian comparison of spatially regularised general linear models. Human Brain Mapping, 2007. 28(4): p. 275-293.

Summary: In previous work (Penny et al., [2005]: Neuroimage 24:350-362) we have developed a spatially regularised General Linear Model for the analysis of functional magnetic resonance imaging data that allows for the characterisation of regionally specific effects using Posterior Probability Maps (PPMs). In this paper we show how it also provides an approximation to the model evidence. This is important as it is the basis of Bayesian model comparison and provides a unified framework for Bayesian Analysis of Variance, Cluster of Interest analyses and the principled selection of signal and noise models. We also provide extensions that implement spatial and anatomical regularisation of noise process parameters. © 2006 Wiley-Liss, Inc.

205. Pastor, M.A., M. Valencia, J. Artieda, M. Alegre, and J.C. Masdeu, Topography of cortical activation differs for fundamental and harmonic frequencies of the steady-state visual-evoked responses. An EEG and PET H 215O study. Cerebral Cortex, 2007. 17(8): p. 1899-1905.

Summary: In humans, visual flicker stimuli of graded frequency (2-90 Hz) elicit an electroencephalographic (EEG) steady-state visual-evoked response (SSVER) with the same fundamental frequency as the stimulus and, in addition, a series of harmonic responses. The fundamental component of the SSVER is generated by increased synaptic activity in primary visual cortex (V1). We set out to determine the cortical origin of the harmonic responses in humans. For this purpose, we recorded the SSVERs at 5 different frequencies (5, 10, 15, 25, and 40 Hz) and measured regional cerebral blood flow (rCBF) with positron emission tomography-H215O at rest and during visual stimulation at the same frequencies. The rCBF contrast weighted by the amplitude of the SSVERs first harmonics showed activation of a swath of cortex perpendicular to V1, including mostly the inferior half of the parieto-occipital sulcus. This area overlapped minimally with the primary visual cortex activated by the fundamental frequency. A different method, estimating EEG cortical source current density with low-resolution brain electromagnetic tomography, gave the same results. Our finding suggests that the inferior portion of the banks of the parieto-occipital sulci contains association visual cortex involved in the processing of stimuli that can be as simple as a flickering light source. © The Author 2006. Published by Oxford University Press. All rights reserved.

206. Papageorgiou, C.C., C. Sfagos, K.K. Kosma, K.A. Kontoangelos, N. Triantafyllou, D. Vassilopoulos, A.D. Rabavilas, and C.R. Soldatos, Changes in LORETA and conventional patterns of P600 after steroid treatment in multiple sclerosis patients. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2007. 31(1): p. 234-241.

Summary: Objective: The P600 component of event-related potentials (ERPs) reflecting the 'rule-governed sequence of information processing', has been associated with multiple sclerosis (MS)-related cognition. The present study aimed at examining the effects of methylprednisolone treatment in MS patients on cognition as reflected by the low-resolution brain electromagnetic tomography (LORETA) of the P600 as well as its conventional constituents (amplitudes and latencies) recorded during a working memory (WM) test. Method: A paired LORETA comparison was performed in the P600 component of ERPs elicited during a (WM) test in 18 MS patients suffering from the relapsing-remitting form, before and after 1 week treatment with methylprednisolone. The P600 component was also evaluated in 16 healthy controls matched to the patients on age and educational level. Results: When pre- and post-treatment recordings of LORETA were compared all patients as a group showed significantly different patterns of current density activation located at right frontal lobe. The treatment was accompanied by an increase of the amplitude of P600 at the right frontoparietal area. In the post-treatment phase the patients exhibited significant improvement of the memory performance as compared to themselves before treatment. As a result both the P600 amplitudes and memory performance at post-treatment were closer to those exhibited by normal controls. Conclusion: These findings support the notion that steroid treatment in relapsing-remitting MS patients, may exert a beneficial effect in 'rule-governed sequence of information processing'. © 2006.

207. Palmero-Soler, E., K. Dolan, V. Hadamschek, and P.A. Tass, swLORETA: A novel approach to robust source localization and synchronization tomography. Physics in Medicine and Biology, 2007. 52(7): p. 1783-1800.

Summary: Standardized low-resolution brain electromagnetic tomography (sLORETA) is a widely used technique for source localization. However, this technique still has some limitations, especially under realistic noisy conditions and in the case of deep sources. To overcome these problems, we present here swLORETA, an improved version of sLORETA, obtained by incorporating a singular value decomposition-based lead field weighting. We show that the precision of the source localization can further be improved by a tomographic phase synchronization analysis based on swLORETA. The phase synchronization analysis turns out to be superior to a standard linear coherence analysis, since the latter cannot distinguish between real phase locking and signal mixing. © 2007 IOP Publishing Ltd.

208. Neuhaus, A.H., S. Koehler, C. Opgen-Rhein, C. Urbanek, E. Hahn, and M. Dettling, Selective anterior cingulate cortex deficit during conflict solution in schizophrenia: An event-related potential study. Journal of Psychiatric Research, 2007. 41(8): p. 635-644.

Summary: Background: Schizophrenia research has gained a new focus on identification and further characterization of neurocognitive deficits in the search for behavioural endophenotypes of this disorder. The objective of this study was to explore differential cortical processing during executive control in schizophrenia as assessed with the attention network test (ANT). Methods: Sixteen schizophrenic patients and sixteen healthy controls matched for gender, age, education, and nicotine consumption were tested with the ANT while recording 29-channel-electroencephalogram (EEG). Visual event-related potentials (ERP) N200 and P300 were topographically analyzed and cortical mapping using low resolution brain electromagnetic tomography (LORETA) was applied to localize neuroelectric generators of ERP. Results: Behaviourally, significant differences between schizophrenic patients and controls were found only for the conflict condition (p < 0.05) and for conflict adjusted by mean reaction time (p < 0.01). Examining ERP of control subjects, N200 failed to show robust flanker congruency effects. P300 amplitude was reduced at Pz (p < 0.05) and P300 latency was increased at Cz (p < 0.005) for the conflict condition. Schizophrenic patients differed significantly in P300 latency at Cz during late conflict processing (p < 0.005). Source analysis revealed a deficit in anterior cingulate cortex (p < 0.05). Conclusion: Our results are in line with previous reports about dysfunctional ACC activation in schizophrenia and argue in favour of a selective deficit of cortical conflict resolution. It is further proposed that dysfunctional ACC activation during executive processing may be a neurophysiologic endophenotype candidate of schizophrenia. © 2006 Elsevier Ltd. All rights reserved.

209. Mulert, C., G. Leicht, O. Pogarell, R. Mergl, S. Karch, G. Juckel, H.J. Möller, and U. Hegerl, Auditory cortex and anterior cingulate cortex sources of the early evoked gamma-band response: Relationship to task difficulty and mental effort. Neuropsychologia, 2007. 45(10): p. 2294-2306.

Summary: High frequency oscillations in the 40 Hz (gamma-band)-range are involved in the synchronization of brain regions, e.g., in cognitive functions. It has been suggested that the auditory evoked gamma-band response (GBR) is affected by attention and apart from auditory cortex activity a frontal or anterior cingulate cortex (ACC) generator could be involved. It was the aim of the present study to address three questions: (1) is there a neural generator of the early evoked GBR in the dorsal (d)ACC? (2) Are there different activation patterns in the dACC and the auditory cortex areas in response to task difficulty? (3) Is it possible to detect an influence of early ACC-gamma-band activity (GBR timeframe) to later auditory information processing (N1 timeframe)? In the present EEG/ERP-study we have investigated 30 healthy subjects using six auditory reaction tasks with increasing difficulty and mental effort demands. In the MANOVA analysis we found a significant main effect of task difficulty on both the GBR amplitude (F = 7.75; p < 0.001) and the auditory evoked N1 potential (F = 7.00; p < 0.001) with higher amplitudes in the more difficult tasks. In the LORETA region of interest (ROI) analysis, this effect was only due to increased dACC-activity during the GBR-timeframe. For the ROI analysis during the N1 timeframe, in addition to a strong effect of task difficulty in the dACC a similar main effect was found in the auditory association area 22. These findings are in line with a top-down influence of dACC-activity to the auditory association area 22 during the early evoked GBR. © 2007 Elsevier Ltd. All rights reserved.

210. Mulert, C., G. Juckel, M. Brunnmeier, S. Karch, G. Leicht, R. Mergl, H.J. Möller, U. Hegerl, and O. Pogarell, Prediction of treatment response in major depression: Integration of concepts. Journal of Affective Disorders, 2007. 98(3): p. 215-225.

Summary: Background: Two promising approaches have been introduced for the prediction of treatment response in major depression: one concept is based on the activity in the rostral anterior cingulate cortex (rACC). Subjects with higher metabolic rates respond better to sleep deprivation or antidepressive medication. Another approach is the investigation of the loudness dependence of the auditory evoked potential (LDAEP). Here, a high LDAEP is supposed to reflect low central serotonergic activity. We present the first study comparing both approaches in the same group of patients. Methods: Patients with major depression (n = 20) were investigated using both resting EEG and LDAEP before treatment with either citalopram or reboxetine. Results: We found significant differences between responders and non-responders in the rACC in the theta-frequency range (6.5-8 Hz, p < 0.05). In the subgroup of patients, treated with citalopram we found higher LDAEP-values in responders versus non-responders (p < 0.05) and a significant correlation between pre-treatment-LDAEP and improvement in the Hamilton score after treatment (r = 0.71, p < 0.05). Conclusions: In combining both methods a prediction whether a patient with major depression might be at risk for non-response to a standard therapy as well as a suggestion for a pharmacological approach of choice seems to be possible. © 2006 Elsevier B.V. All rights reserved.

211. Mulert, C., G. Juckel, M. Brunnmeier, S. Karch, G. Leicht, R. Mergl, H.J. Möller, U. Hegerl, and O. Pogarell, Rostral anterior cingulate cortex activity in the theta band predicts response to antidepressive medication. Clinical EEG and Neuroscience, 2007. 38(2): p. 78-81.

Summary: During the last 10 years the knowledge about rostral anterior cingulate cortex (ACC) activity in major depression has substantially increased. Several groups have independently described a relationship between resting activity in this area and response to antidepressant treatment. We have recently confirmed a relationship between resting activity of rostral ACC activity and response in a group of 20 patients with major depression using resting theta activity. In this earlier study regions of interest (ROI) were defined in order to establish regional specificity. Differences between responders and nonresponders were only found in the ACC-ROI, but not in the posterior cingulate region. We have now reanalyzed our data using a whole brain voxelwise approach, in order not to miss any other relevant functional differences. In addition to major differences between responders and nonresponders in the rostral ACC, we have identified a nearby region in the midline orbito-frontal region.

212. Mucci, A., S. Galderisi, B. Kirkpatrick, P. Bucci, U. Volpe, E. Merlotti, F. Centanaro, F. Catapano, and M. Maj, Double dissociation of N1 and P3 abnormalities in deficit and nondeficit schizophrenia. Schizophrenia Research, 2007. 92(1-3): p. 252-261.

Summary: It has been proposed that the presence of enduring, idiopathic negative symptoms define a group of patients with a disease (deficit schizophrenia, DS) that is separate from other forms of schizophrenia (nondeficit schizophrenia, NDS). Although several findings support this hypothesis, the possibility that DS represents the severe end of a single schizophrenia continuum cannot be excluded yet. We tested the hypothesis that DS and NDS differ relative to event-related potentials (ERPs). Amplitude, scalp topography and cortical sources of the ERP components were assessed in clinically stable DS and NDS outpatients and in matched healthy subjects (HCS). Twenty subjects per group were recruited. Among the subjects who completed the target detection task, there were no group difference in accuracy. For N1, only patients with DS, as compared with HCS, showed an amplitude reduction over the scalp central leads and a reduced current source density in cingulate and parahippocampal gyrus. For P3, only patients with NDS, as compared with HCS, showed a lateralized amplitude reduction over the left posterior regions and reduced current source density in left temporal and bilateral frontal, cingulate and parietal areas. The DS and NDS groups differed significantly from each other with regard to N1 amplitude and topography, as well as P3 amplitude and cortical sources. The N1 was affected in DS but not in NDS patients, whereas P3 was affected in NDS only. This double dissociation is consistent with the hypothesis that DS represents a separate disease entity within schizophrenia. © 2007 Elsevier B.V. All rights reserved.

213. Mössner, R., O. Mikova, E. Koutsilieri, M. Saoud, A.C. Ehlis, N. Müller, A.J. Fallgatter, and P. Riederer, Consensus paper of the WFSBP task force on biological markers: Biological markers in depression. World Journal of Biological Psychiatry, 2007. 8(3): p. 141-174.

Summary: Biological markers for depression are of great interest to aid in elucidating the causes of major depression. We assess currently available biological markers to query their validity for aiding in the diagnosis of major depression. We specifically focus on neurotrophic factors, serotonergic markers, biochemical markers, immunological markers, neuroimaging, neurophysiological findings, and neuropsychological markers. We delineate the most robust biological markers of major depression. These include decreased platelet imipramine binding, decreased 5-HT1A receptor expression, increase of soluble interleukin-2 receptor and interleukin-6 in serum, decreased brain-derived neurotrophic factor in serum, hypocholesterolemia, low blood folate levels, and impaired suppression of the dexamethasone suppression test. To date, however, none of these markers are sufficiently specific to contribute to the diagnosis of major depression. Thus, with regard to new diagnostic manuals such as DSM-V and ICD-11 which are currently assessing whether biological markers may be included in diagnostic criteria, no biological markers for major depression are currently available for inclusion in the diagnostic criteria.

214. Möller, J., B.M. Jansma, A. Rodriguez-Fornells, and T.F. Münte, What the brain does before the tongue slips, in Cerebral Cortex. 2007. p. 1173-1178.

215. Minsley, B.J., J. Sogade, and F.D. Morgan, Three-dimensional source inversion of self-potential data. Journal of Geophysical Research B: Solid Earth, 2007. 112(2).

Summary: The self-potential (SP) method has long been used for a variety of geophysical applications because of its ease of acquisition, but has suffered from difficulty in interpretation of the data. Self-potential signals result from a source term that is coupled with the earth resistivity and appropriate boundary conditions. This work describes an inversion methodology for determining the self-potential sources from measured SP and resistivity data. The SP source inversion is a linear problem, though it is complicated by nonuniqueness that is common to potential-field problems. The linear operator is also poorly conditioned because of the limited set of measurements, which are often constrained to the earth's surface. Our approach utilizes model regularization that selects a class of solutions which fit the data with sources that are spatially compact. Large variations in sensitivity due to distance and resistivity structure throughout the model are addressed through the use of a scaling term derived from the Green's functions that define the linear operator. A significant benefit of these methods is the resolution of targets at depth from surface measurements alone. This inversion technique is first illustrated with a simple synthetic data set. In a second example we apply this approach to a field data set taken from previously published literature and investigate the effects of different resistivity structure assumptions on the inversion results. The spatial distribution of sources provides useful information that can subsequently be interpreted in terms of physical processes that generate the SP data. Copyright 2007 by the American Geophysical Union.

216. Meyer, M., S. Elmer, S. Baumann, and L. Jancke, Short-term plasticity in the auditory system: Differential neural responses to perception and imagery of speech and music. Restorative Neurology and Neuroscience, 2007. 25(3-4): p. 411-431.

Summary: Purpose: In this EEG study we sought to examine the neuronal underpinnings of short-term plasticity as a top-down guided auditory learning process. We hypothesized, that (i) auditory imagery should elicit proper auditory evoked effects (N1/P2 complex) and a late positive component (LPC). Generally, based on recent human brain mapping studies we expected (ii) to observe the involvement of different temporal and parietal lobe areas in imagery and in perception of acoustic stimuli. Furthermore we predicted (iii) that temporal regions show an asymmetric trend due to the different specialization of the temporal lobes in processing speech and non-speech sounds. Finally we sought evidence supporting the notion that short-term training is sufficient to drive top-down activity in brain regions that are not normally recruited by sensory induced bottom up processing. Methods: 18 non-musicians partook in a 30 channels based EEG session that investigated spatio-temporal dynamics of auditory imagery of "consonant-vowel" (CV) syllables and piano triads. To control for conditioning effects, we split the volunteers in two matched groups comprising the same conditions (visual, auditory or bimodal stimulation) presented in a slightly different serial order. Furthermore the study presents electromagnetic source localization (LORETA) of perception and imagery of CV- and piano stimuli. Results: Our results imply that auditory imagery elicited similar electrophysiological effects at an early stage (N1/P2) as auditory stimulation. However, we found an additional LPC following the N1/P2 for auditory imagery only. Source estimation evinced bilateral engagement of anterior temporal cortex, which was generally stronger for imagery of music relative to imagery of speech. While we did not observe lateralized activity for the imagery of syllables we noted significantly increased rightward activation over the anterior supratemporal plane for musical imagery. Conclusion: Thus, we conclude that short-term top-down training based auditory imagery of music and speech prompts involvement of distinct neural circuits residing in the perisylvian cortex. © 2007 - IOS Press and the authors. All rights reserved.

217. Meltzer, J.A., M. Negishi, L.C. Mayes, and R.T. Constable, Individual differences in EEG theta and alpha dynamics during working memory correlate with fMRI responses across subjects. Clinical Neurophysiology, 2007. 118(11): p. 2419-2436.

Summary: Objective: Theta and alpha range EEG oscillations are commonly induced in cognitive tasks, but their possible relationship to the BOLD signal of fMRI is not well understood, and individual variability is high. We explored individual differences in EEG reactivity to determine whether it is positively or negatively correlated with BOLD across subjects. Methods: A Sternberg working memory task with 2, 4, or 6 digits was administered to 18 subjects in separate fMRI and EEG sessions. Memory load-dependent theta and alpha reactivity was quantified and used as a regressor to reveal brain areas exhibiting EEG-fMRI correlation across subjects. Results: Theta increases localized to medial prefrontal cortex, and correlated negatively with BOLD in that region and in other "default mode" areas. Alpha modulation localized to parietal-occipital midline cortex and also correlated negatively with BOLD. Conclusions: Individual tendencies to exhibit memory load-dependent oscillations are associated with negative BOLD responses in certain brain regions. Significance: Positive BOLD responses and increased EEG oscillations do not necessarily arise in the same regions. Negative BOLD responses may also relate to cognitive activity, as traditionally indexed by increased EEG power in the theta band. © 2007 International Federation of Clinical Neurophysiology.

218. Mazerolle, E.L., R.C.N. D'Arcy, Y. Marchand, and R.B. Bolster, ERP assessment of functional status in the temporal lobe: Examining spatiotemporal correlates of object recognition, in International Journal of Psychophysiology. 2007. p. 81-92.

219. Maurer, U., S. Brem, K. Bucher, F. Kranz, R. Benz, H.C. Steinhausen, and D. Brandeis, Impaired tuning of a fast occipito-temporal response for print in dyslexic children learning to read. Brain, 2007. 130(12): p. 3200-3210.

Summary: Developmental dyslexia is defined as a disorder of learning to read. It is thus critical to examine the neural processes that impair learning to read during the early phase of reading acquisition, before compensatory mechanisms are adapted by older readers with dyslexia. Using electroencephalography-based event-related imaging, we investigated how tuning of visual activity for print advances in the same children before and after initial reading training in school. The focus was on a fast, coarse form of visual tuning for print, measured as an increase of the occipito-temporal N1 response at 150-270 ms in the event-related potential (ERP) to words compared to symbol strings. The results demonstrate that the initial development of reading skills and visual tuning for print progressed more slowly in those children who became dyslexic than in their control peers. Print-specific tuning in 2nd grade strongly distinguished dyslexic children from controls. It was maximal in the inferior occipito-temporal cortex, left-lateralized in controls, and reduced in dyslexic children. The results suggest that delayed initial visual tuning for print critically contributes to the development of dyslexia. © The Author (2007). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved.

220. Litvak, V., S. Komssi, M. Scherg, K. Hoechstetter, J. Classen, M. Zaaroor, H. Pratt, and S. Kahkonen, Artifact correction and source analysis of early electroencephalographic responses evoked by transcranial magnetic stimulation over primary motor cortex. NeuroImage, 2007. 37(1): p. 56-70.

Summary: Analyzing the brain responses to transcranial magnetic stimulation (TMS) using electroencephalography (EEG) is a promising method for the assessment of functional cortical connectivity and excitability of areas accessible to this stimulation. However, until now it has been difficult to analyze the EEG responses during the several tens of milliseconds immediately following the stimulus due to TMS-induced artifacts. In the present study we show that by combining a specially adapted recording system with software artifact correction it is possible to remove a major part of the artifact and analyze the cortical responses as early as 10 ms after TMS. We used this methodology to examine responses of left and right primary motor cortex (M1) to TMS at different intensities. Based on the artifact-corrected data we propose a model for the cortical activation following M1 stimulation. The model revealed the same basic response sequence for both hemispheres. A large part of the response could be accounted for by two sources: a source close to the stimulation site (peaking ∼ 15 ms after the stimulus) and a midline frontal source ipsilateral to the stimulus (peaking ∼ 25 ms). In addition the model suggests responses in ipsilateral temporo-parietal junction areas (∼ 35 ms) and ipsilateral (∼ 30 ms) and middle (∼ 50 ms) cerebellum. Statistical analysis revealed significant dependence on stimulation intensity for the ipsilateral midline frontal source. The methodology developed in the present study paves the way for the detailed study of early responses to TMS in a wide variety of brain areas. © 2007 Elsevier Inc. All rights reserved.

221. Li, Y.O., T. Adali, and V.D. Calhoun, Estimating the number of independent components for functional magnetic resonance imaging data. Human Brain Mapping, 2007. 28(11): p. 1251-1266.

Summary: Multivariate analysis methods such as independent component analysis (ICA) have been applied to the analysis of functional magnetic resonance imaging (fMRI) data to study brain function. Because of the high dimensionality and high noise level of the fMRI data, order selection, i.e., estimation of the number of informative components, is critical to reduce over/underfitting in such methods. Dependence among fMRI data samples in the spatial and temporal domain limits the usefulness of the practical formulations of information-theoretic criteria (ITC) for order selection, since they are based on likelihood of independent and identically distributed (i.i.d.) data samples. To address this issue, we propose a subsampling scheme to obtain a set of effectively i.i.d. samples from the dependent data samples and apply the ITC formulas to the effectively i.i.d. sample set for order selection. We apply the proposed method on the simulated data and show that it significantly improves the accuracy of order selection from dependent data. We also perform order selection on fMRI data from a visuomotor task and show that the proposed method alleviates the over-estimation on the number of brain sources due to the intrinsic smoothness and the smooth preprocessing of fMRI data. We use the software package ICASSO (Himberg et al. [2004]: Neuroimage 22:1214-1222) to analyze the independent component (IC) estimates at different orders and show that, when ICA is performed at overestimated orders, the stability of the IC estimates decreases and the estimation of task related brain activations show degradation. © 2007 Wiley-Liss, Inc.

222. Li, Y.O., T. Adali, and V.D. Calhoun, A feature-selective independent component analysis method for functional MRI. International Journal of Biomedical Imaging, 2007. 2007.

Summary: In this work, we propose a simple and effective scheme to incorporate prior knowledge about thesources of interest (SOIs) in independent component analysis (ICA) and apply the method to estimatebrain activations from functional magnetic resonance imaging (fMRI) data. We name the proposedmethod as feature-selective ICA since it incorporates the features in the sample space of the independentcomponents during ICA estimation. The feature-selective scheme is achieved through a filtering operationin the source sample space followed by a projection onto the demixing vector space by a least squaresprojection in an iterative ICA process. We perform ICA estimation of artificial activations superimposedinto a resting state fMRI dataset to show that the feature-selective scheme improves the detection ofinjected activation from the independent component estimated by ICA. We also compare the task-relatedsources estimated from true fMRI data by a feature-selective ICA algorithm versus an ICA algorithmand show evidence that the feature-selective scheme helps improve the estimation of the sources in bothspatial activation patterns and the time courses.

223. Li, L. and D. Yao, A new method of spatio-temporal topographic mapping by correlation coefficient of k-means cluster. Brain Topography, 2007. 19(4): p. 161-176.

Summary: It would be of the utmost interest to map correlated sources in the working human brain by Event-Related Potentials (ERPs). This work is to develop a new method to map correlated neural sources based on the time courses of the scalp ERPs waveforms. The ERP data are classified first by k-means cluster analysis, and then the Correlation Coefficients (CC) between the original data of each electrode channel and the time course of each cluster centroid are calculated and utilized as the mapping variable on the scalp surface. With a normalized 4-concentric-sphere head model with radius 1, the performance of the method is evaluated by simulated data. CC, between simulated four sources (s 1-s4) and the estimated cluster centroids (c 1-c4), and the distances (Ds), between the scalp projection points of the s1-s4 and that of the c 1-c4, are utilized as the evaluation indexes. Applied to four sources with two of them partially correlated (with maximum mutual CC = 0.4892), CC (Ds) between s 1-s4 and c1-c 4 are larger (smaller) than 0.893 (0.108) for noise levels NSR ≤ 0.2; Applied to four sources with two of them completely correlated, CC (Ds) between s1-s4 and c1-c4 are larger (smaller) than 0.97367 (0.1898) for a random noise level NSR ≤ 0.2; Applied to 128, 64 and 32 recording electrodes, CC (Ds) between s1-s 4 and c1-c4 are larger (smaller) than 0.9557 (0.4251) for a random noise level NSR = 0.15; And applied to the cases of spatially overlapped scalp activities, CC (Ds) between s 1-s 4 and c1-c4 are larger (smaller) than 0.9083 (0.4329) for a random noise level NSR = 0.15. Finally, the method successfully decomposed the ERPs collected in a spatial selective attention experiment into three clusters located at left, right occipital and frontal. The estimated vectors of the contra-occipital area demonstrate that attention to the stimulus location produces increased amplitude of the P1 and N1 components over the contra-occipital scalp. The estimated vector in the frontal area displays two large processing negativity waves around 100 ms and 250 ms when subjects are attentive, and there is a small negative wave around 140 ms and a P300 when subjects are unattentive. The results of simulations and real Visual Evoked Potentials (VEPs) data demonstrate the validity of the method in mapping correlated sources. This method may be an objective, heuristic and important tool to study the properties of cerebral, neural networks in cognitive and clinical neurosciences. © 2007 Springer Science+Business Media, LLC.

224. Lengger, P.G., F.P.S. Fischmeister, H. Leder, and H. Bauer, Functional neuroanatomy of the perception of modern art: A DC-EEG study on the influence of stylistic information on aesthetic experience, in Brain Research. 2007. p. 93-102.

225. Kopřivová, J., J. Praško, M. Brunovský, M. Raszka, T. Novák, and J. Horáček, Functional connectivity in obsessive-compulsive disorder: A correlation analysis of low-resolution brain electromagnetic tomography (LORETA). Funkční konektivita u obsedantně-kompulzivní poruchy: Korelační analýza elektromagnetické mozkové tomografie (LORETA), 2007. 11(SUPPL. 3): p. 99-104.

Summary: This study compared cortical functional connectivity between patients with obsessive-compulsive disorder (OCD) and healthy controls using voxel-wise electrical activity (current density) correlations estimated by LORETA (low-resolution brain electromagnetic tomography). 16 OCD patients (10 men and 6 women) on stable, benzodiazepine-free medication participated in the study. The mean current density in three a priori selected homologous cortical regions (anterior cingulate, superior temporal cortex and orbitofrontal cortex) was correlated in time with current density in the remaining of 2394 cortical voxels. The individual z-scores obtained by normative database comparisons were analyzed with randomization-permutation statistics. In OCD patients, anterior cingulate and orbitofrontal cortex showed significantly lower correlations with a large frontotemporal region of the right hemisphere, mainly in the low-frequency band. Disconnection of the superior temporal cortex was less pronounced and showed a lateralized, slightly different frequency and topographic pattern. Our findings suggest that deficient right-hemispheric functional connections in inhibitory activities might be involved in the pathophysiology of OCD.

226. Kopřivová, J., J. Praško, M. Brunovský, and J. Horáček, Independent component analysis of the EEG signal and its application in a patient with obsessive-compulsive disorder. Využití analýzy nezávislých komponent EEG signálu u nemocného s obsedantně-kompulzivní poruchou, 2007. 11(4): p. 240-243.

Summary: We demonstrate the potential diagnostic and therapeutic use of electrical brain activity information decomposed via independent component analysis (ICA) in an obsessive-compulsive patient. The resting EEG was analyzed by sLORETA (standardized low-resolution electromagnetic tomography) and by the ICA using the Independent Component Neurofeedback software (ICoN, Nova Tech EEG, Inc). The sLORETA normative database comparison (Nova Tech EEG, Inc) revealed increase of absolute power in the theta frequency band, especially in the anterior cingulate and orbitofrontal gyrus whose involvement in OCD pathophysiology has been previously reported. Abnormal theta waves were also detectable by visual EEG inspection. The ICA identified their main source, localized in the affective part of the anterior cingulate and in the medial orbitofrontal cortex. With respect to out findings we hypothesize that neurofeedback aimed at decreasing theta activity of this source might lead to the normalization of dysfunctional neural network and thus improve clinical symptoms.

227. Kleinlogel, H., W. Strik, and S. Begré, Increased NoGo-anteriorisation in first-episode schizophrenia patients during Continuous Performance Test. Clinical Neurophysiology, 2007. 118(12): p. 2683-2691.

Summary: Objective: NoGo-stimuli during a Continuous Performance Test (CPT) activate prefrontal brain structures such as the anterior cingulate gyrus and lead to an anteriorisation of the positive electrical field of the NoGo-P300 relative to the Go-P300, so-called NoGo-anteriorisation (NGA). NGA during CPT is regarded as a neurophysiological standard index for cognitive response control. While it is known that patients with chronic schizophrenia exhibit a significant reduction in NGA, it is unclear whether this also occurs in patients undergoing their first-episode. Thus, the aim of the present study was to determine NGA in a group of patients with first-episode schizophrenia by utilizing a CPT paradigm. Methods: Eighteen patients with first-episode schizophrenia and 18 matched healthy subjects were investigated electrophysiologically during a cued CPT, and the parameters of the Go- and NoGo-P300 were determined using microstate analysis. Low resolution tomography analysis (LORETA) was used for source determination. Results: Due to a more posterior Go- and a more anterior NoGo-centroid, NGA was greater in patients than in healthy controls. LORETA indicated the same sources for both groups after Go-stimuli, but a more anterior source in patients after NoGo-stimuli. In patients P300-amplitude responses to both Go- and NoGo-stimuli were decreased, and P300-latency to NoGo-stimuli was increased. After the Go-stimuli false reactions and reaction times were increased in patients. Conclusions: Attention was reduced in patients with first-episode schizophrenia, as indicated by more false reactions, prolongation of reaction time, P300-latencies and by a decrease in P300-amplitude. Significantly however, the NGA and prefrontal LORETA-sources indicate intact prefrontal brain structures in first-episode schizophrenia patients. Previously described changes in this indicator of prefrontal function may be related to a progressive decay in chronic schizophrenia. Significance: The results support the idea of a possible new biological marker of first episode psychosis, which may be a useful parameter for the longitudinal measurement of changing prefrontal brain function in a single schizophrenia patient. © 2007 International Federation of Clinical Neurophysiology.

228. Kawasaki, Y., T. Sumiyoshi, Y. Higuchi, T. Ito, M. Takeuchi, and M. Kurachi, Voxel-based analysis of P300 electrophysiological topography associated with positive and negative symptoms of schizophrenia. Schizophrenia Research, 2007. 94(1-3): p. 164-171.

Summary: Abnormal P300 waveforms of the event-related potentials during the auditory oddball task are one of the most consistent findings in patients with schizophrenia. In the present study, we sought to test the hypothesis that the abnormal P300 waveform results from composite representation of neural activity in anatomically distinct brain regions responsible for the manifestation of positive and negative symptoms. We used the low-resolution brain electromagnetic tomography (LORETA) to obtain current density images of the P300 component from 26 patients with schizophrenia. The statistical parametric mapping (SPM) was applied to the LORETA images in order to identify brain regions that are related with the severity of psychotic symptoms as evaluated by the Brief Psychiatric Rating Scale (BPRS). The BPRS Total score was negatively correlated with the P300 current density in the left superior temporal gyrus (r = - 0.615, corrected p = 0.009) and that in the right medial frontal region (r = - 0.571, corrected p = 0.019) by means of SPM single-subject covariates model. These brain regions were included in the region-specific P300 sources as represented by the current density maxima (corrected p < 0.05) using SPM one-sample t-test. A subsequent region-of-interest analysis of Pearson correlations revealed specific relationships between the Positive subscale score and the mean current density in the left superior temporal gyrus (r = - 0.528, p = 0.005) and between the Negative subscale score and the mean current densities in the medial frontal region (r = - 0.551, p = 0.003) and left superior temporal gyrus (r = - 0.499, p = 0.009). These results indicate that functional disturbances of neural networks involving the medial prefrontal and superior temporal regions may be responsible for the generation of positive and the negative psychotic symptoms of schizophrenia. © 2007 Elsevier B.V. All rights reserved.

229. Kam, S.C., O.Y. Kwon, and J.S. Hyun, Location of brain electrical source activation by visually stimulated sexual arousal in young men and women: A cross spectral analysis using low resolution brain electromagnetic tomography (LORETA). Korean Journal of Urology, 2007. 48(3): p. 333-343.

Summary: Purpose: To investigate the locations of the cerebral cortex activated by visually stimulated sexual arousal, and to discriminate the gender differences between the cortical activation patterns in response to sexual stimuli. Materials and Methods: Thirty-two male and the twenty-one female volunteers from right-handed medical students were enrolled in this study. The electroencephatography (EEGs) included the segments recorded during resting, watching a music-video, intermission and watching a pornographic video. The low-resolution brain electromagnetic tomography (LORETA) images of cross-spectral analysis were obtained from the segments using the LORETA-KEY software. Results: The beta 1, 2 and 3 activities of males showed the point of maximal current densities in both the uncus and parahippocampal gyrus of the left limbic lobe, the anterior cingulate of the right limbic lobe, the superior temporal gyrus of both temporal lobes, the precuneus of the right parietal lobe, the medial frontal gyrus and superior frontal gyrus of the right frontal lobe, the superior parietal lobule of the right parietal lobe, and the middle occipital gyrus of both occipital lobes. The delta, theta, alpha and beta 1 activities of females showed the point of maximal current densities in the postcentral gyrus and inferior parietal lobule of the left parietal lobe, the middle frontal gyrus of the left frontal lobe, the middle occipital gyrus of the left occipital lobe, the left cuneus, the superior temporal gyrus of both temporal lobes and the left parahippocampal gyrus. Conclusions: There was a difference in the visually stimulated sexual arousal-associated with the cerebral neuroanatomical areas between men and women, as estimated using the LORETA software. These areas; therefore, were thought to play important roles in the sexual arousal of males and females in response to audiovisual sexual stimulation.

230. Jiangang, L. and T. Jie, Spatiotemporal analysis of single-trial EEG of emotional pictures based on Independent Component Analysis and source location. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2007. 6511(PART 2).

Summary: The present study combined the Independent Component Analysis (ICA) and low-resolution brain electromagnetic tomography (LORETA) algorithms to identify the spatial distribution and time course of single-trial EEG record differences between neural responses to emotional stimuli vs. the neutral. Single-trial multichannel (129-sensor) EEG records were collected from 21 healthy, right-handed subjects viewing the emotion emotional (pleasant/unpleasant) and neutral pictures selected from International Affective Picture System (IAPS). For each subject, the single-trial EEG records of each emotional pictures were concatenated with the neutral, and a three-step analysis was applied to each of them in the same way. First, the ICA was performed to decompose each concatenated single-trial EEG records into temporally independent and spatially fixed components, namely independent components (ICs). The IC associated with artifacts were isolated. Second, the clustering analysis classified, across subjects, the temporally and spatially similar ICs into the same clusters, in which nonparametric permutation test for Global Field Power (GFP) of IC projection scalp maps identified significantly different temporal segments of each emotional condition vs. neutral. Third, the brain regions accounted for those significant segments were localized spatially with LORETA analysis. In each cluster, a voxel-by-voxel randomization test identified significantly different brain regions between each emotional condition vs. the neutral. Compared to the neutral, both emotional pictures elicited activation in the visual, temporal, ventromedial and dorsomedial prefrontal cortex and anterior cingulated gyrus. In addition, the pleasant pictures activated the left middle prefrontal cortex and the posterior precuneus, while the unpleasant pictures activated the right orbitofrontal cortex, posterior cingulated gyrus and somatosensory region. Our results were well consistent with other functional imaging studies, while revealed temporal dynamics of emotional processing of specific brain structure with high temporal resolution.

231. Jaušovec, N. and K. Jaušovec, Personality, gender and brain oscillations. International Journal of Psychophysiology, 2007. 66(3): p. 215-224.

Summary: The aim of the study was to investigate the relationship between personality structure and brain activity of individuals while resting with eyes closed. In the experiment 110 individuals participated (55 males and 55 females). They were clustered into 5 personality types according to the dimensions of general and emotional intelligence, and the five-factor personality model (FFM) - extraversion (E), neuroticism (N), openness (O), conscientiousness (C) and agreeableness (A). The resting EEG of individuals was analyzed using three methods: a Fast Fourier Transformation (FFT); Approximated entropy (ApEn), and a low resolution brain electromagnetic tomography (LORETA). The results show that most robust differences between personality types were observed in the gamma band, between types with extreme constellations of dimensions (neurotic type - low emotional intelligence and A; high N), or between types with specific combinations of dimensions (introverts with high IQ, versus extraverts with low to average IQ). These differences were also gender specific. In the gamma band females with different personality structures differed much more than did males, whereas in the lower-1 alpha band a reverse pattern was observed. It was further shown that the differences were much more pronounced in the parieto-occipital brain areas than in the frontal areas. © 2007 Elsevier B.V. All rights reserved.

232. Im, C.H., H.K. Jung, K.Y. Jung, and S.Y. Lee, Reconstruction of continuous and focalized brain functional source images from electroencephalography. IEEE Transactions on Magnetics, 2007. 43(4): p. 1709-1712.

Summary: In this paper, a new hybrid approach to reconstruct more accurate brain functional source images from electroencephalography is proposed. The proposed approach combines extended source model and focal underdetermined system solution algorithm. Feasibility studies with realistic simulation data and the epilepsy patient's data demonstrate that continuous, as well as focalized, brain electrical source images can be reconstructed utilizing the proposed approach. © 2007 IEEE.

233. Im, C.H., Dealing with mismatched fMRI activations in fMRI constrained EEG cortical source imaging: A simulation study assuming various mismatch types. Medical and Biological Engineering and Computing, 2007. 45(1): p. 79-90.

Summary: Although fMRI constrained EEG source imaging could be a promising approach to enhancing both spatial and temporal resolutions of independent fMRI and EEG analyses, it has been frequently reported that a hard fMRI constraint may cause severe distortion or elimination of significant EEG sources when there are distinct mismatches between fMRI activations and EEG sources. If estimating actual EEG source locations is important and fMRI prior information is used as an auxiliary tool to enhance the concentration of widespread EEG source distributions, it is reasonable to weaken the fMRI constraint when significantly mismatched sources exist. The present study demonstrates that the mismatch problem may be partially solved by extending the prior fMRI activation regions based on the conventional source imaging results. A hard fMRI constraint is then applied when there is no distinct mismatch, while a weakened fMRI constraint is applied when there are significant mismatches. A preliminary simulation study assuming different types of mismatches such as fMRI invisible, extra, and discrepancy sources demonstrated that this approach can be a promising option to treat mismatched fMRI activations in fMRI constrained EEG source imaging. © International Federation for Medical and Biological Engineering 2006.

234. Hsiao, J.H.w., R. Shillcock, and C.y. Lee, Neural correlates of foveal splitting in reading: Evidence from an ERP study of Chinese character recognition. Neuropsychologia, 2007. 45(6): p. 1280-1292.

Summary: Recent research on foveal structure and reading suggests that the two halves of a centrally fixated word seem to be initially projected to, and processed in, different hemispheres. In the current study, we utilize two contrasting structures in Chinese orthography, "SP" (the semantic radical on the left and the phonetic radical on the right) and "PS" characters (the opposite structure), to examine foveal splitting effects in event-related potential (ERP) recordings. We showed that when participants silently named centrally presented characters, there was a significant interaction between character type and hemisphere in N1 amplitude: SP characters elicited larger N1 compared with PS characters in the left hemisphere, whereas the right hemisphere had the opposite pattern. This effect is consistent with the split fovea claim, suggesting that the two halves of a character may be initially projected to and processed in different hemispheres. There was no such interaction observed in an earlier component P1. Also, there was an interaction between character type and sex of the reader in N350 amplitude. This result is consistent with Hsiao and Shillcock's [Hsiao, J. H., & Shillcock, R. (2005b). Foveal splitting causes differential processing of Chinese orthography in the male and female brain. Cognitive Brain Research, 25, 531-536] behavioural study, which showed a similar interaction in naming response time. They argued that this effect was due to a more left-lateralized network for phonological processing in the male brain compared with the female brain. The results hence showed that foveal splitting effects in visual word recognition were observed in N1 the earliest, and could extend far enough to interact with the sex of the reader as revealed in N350. © 2006 Elsevier Ltd. All rights reserved.

235. Horev, N., T. Most, and H. Pratt, Categorical perception of speech (VOT) and analogous non-speech (FOT) signals: Behavioral and electrophysiological correlates. Ear and Hearing, 2007. 28(1): p. 111-128.

Summary: OBJECTIVE: To determine whether voicing perception is influenced primarily by linguistic experience or if it is due to innate temporal sensitivity to voicing boundaries, by examining behavioral and electrophysiological correlates of speech Voice-Onset-Time (VOT) and nonspeech Formant-Onset-Time (FOT) categorical perception. DESIGN: Behavioral measures and auditory event-related potentials (ERPs) were obtained from 14 normal-hearing Hebrew speakers, whose voicing distinction is different than English, during identification and discrimination of two sets of stimuli: a VOT continuum, created by editing natural productions of /ba/ and /pa/, and an analogous nonspeech continuum, composed of two synthesized formants, varying in their onset time-FOT. RESULTS: VOT and FOT continua yielded similar behavioral identification curves. Differences between the two stimulus types were found in discrimination of within-category differences and in reaction time effects. During identification and discrimination tasks, ERPs were differently affected by the VOT or FOT value of the stimulus: VOT value had a significant effect on N1 latency and on N1 and P2 amplitudes whereas FOT value had a significant effect on P2 amplitude. Additionally, during identification tasks, whereas all speech signals evoked a P3, regardless of overt categorization, only the perceptually "rare" nonspeech stimulus (+15 msec FOT) evoked a P3. CONCLUSIONS: Voicing boundaries corresponded to Hebrew VOT values of production, suggesting that voicing perception in Hebrew is mediated mainly by linguistic experience rather than by innate temporal sensitivity. ERP data differed to VOT versus FOT stimuli as early as N1, indicating that brain processing of the temporal aspects of speech and nonspeech signals differ from their early stages. Further studies to establish the neural response patterns to voicing in speakers of languages that use different voicing categories than English are warranted. © 2007 Lippincott Williams & Wilkins, Inc.

236. Horacek, J., M. Brunovsky, T. Novak, L. Skrdlantova, M. Klirova, V. Bubenikova-Valesova, V. Krajca, B. Tislerova, M. Kopecek, F. Spaniel, P. Mohr, and C. Höschl, Effect of low-frequency rTMS on electromagnetic tomography (LORETA) and regional brain metabolism (PET) in schizophrenia patients with auditory hallucinations. Neuropsychobiology, 2007. 55(3-4): p. 132-142.

Summary: Background: Auditory hallucinations are characteristic symptoms of schizophrenia with high clinical importance. It was repeatedly reported that low frequency (≤1Hz) repetitive transcranial magnetic stimulation (rTMS) diminishes treatment-resistant auditory hallucinations. A neuroimaging study elucidating the effect of rTMS in auditory hallucinations has yet to be published. Objective: To evaluate the distribution of neuronal electrical activity and the brain metabolism changes after low-frequency rTMS in patients with auditory hallucinations. Methods: Low-frequency rTMS (0.9 Hz, 100% of motor threshold, 20 min) applied to the left temporoparietal cortex was used for 10 days in the treatment of medication-resistant auditory hallucinations in schizophrenia (n = 12). The effect of rTMS on the low-resolution brain electromagnetic tomography (LORETA) and brain metabolism (18FDG PET) was measured before and after 2 weeks of treatment. Results: We found a significant improvement in the total and positive symptoms (PANSS), and on the hallucination scales (HCS, AHRS). The rTMS decreased the brain metabolism in the left superior temporal gyrus and in interconnected regions, and effected increases in the contralateral cortex and in the frontal lobes. We detected a decrease in current densities (LORETA) for the beta-1 and beta-3 bands in the left temporal lobe whereas an increase was found for beta-2 band contralaterally. Conclusion: Our findings implicate that the effect is connected with decreased metabolism in the cortex underlying the rTMS site, while facilitation of metabolism is propagated by transcallosal and intrahemispheric connections. The LORETA indicates that the neuroplastic changes affect the functional laterality and provide the substrate for a metabolic effect. Copyright © 2007 S. Karger AG.

237. Henson, R.N., J. Mattout, K.D. Singh, G.R. Barnes, A. Hillebrand, and K. Friston, Population-level inferences for distributed MEG source localization under multiple constraints: Application to face-evoked fields. NeuroImage, 2007. 38(3): p. 422-438.

Summary: We address some key issues entailed by population inference about responses evoked in distributed brain systems using magnetoencephalography (MEG). In particular, we look at model selection issues at the within-subject level and feature selection issues at the between-subject level, using responses evoked by intact and scrambled faces around 170 ms (M170). We compared the face validity of subject-specific forward models and their summary statistics in terms of how estimated responses reproduced over subjects. At the within-subject level, we focused on the use of multiple constraints, or priors, for inverting distributed source models. We used restricted maximum likelihood (ReML) estimates of prior covariance components (in both sensor and source space) and show that their relative importance is conserved over subjects. At the between-subject level, we used standard anatomical normalization methods to create posterior probability maps that furnish inference about regionally specific population responses. We used these to compare different summary statistics, namely; (i) whether to test for differences between condition-specific source estimates, or whether to test the source estimate of differences between conditions, and (ii) whether to accommodate differences in source orientation by using signed or unsigned (absolute) estimates of source activity. Crown Copyright © 2007.

238. Hanslmayr, S., W. Klimesch, P. Sauseng, W. Gruber, M. Doppelmayr, R. Freunberger, T. Pecherstorfer, and N. Birbaumer, Alpha phase reset contributes to the generation of ERPs. Cerebral Cortex, 2007. 17(1): p. 1-8.

Summary: An unresolved question in electroencephalogram (EEG) research is whether event-related potentials (ERPs) are generated by phase-reset or evoked response. We analyzed data of a visual feature detection task and will show 1) phase concentration in the alpha frequency range, 2) ongoing alpha activity prior to stimulus onset, 3) evoked alpha oscillation in the ERP, 4) lack of power increase during phase concentration, 5) decrease in amplitude variance during early evoked components preceding a decrease in power, and 6) the same cortical sources for induced prestimulus power and evoked poststimulus power. Because none of these data provide unequivocal evidence for phase reset, we additionally tested the basic assumption of the evoked model, which is the additivity of the evoked response on the basis of a simulation approach. Our findings suggest that nonadditive processes - typical for a phase reset - are involved in the generation of the ERP. Thus, together with the other findings this study provides unequivocal evidence for phase resetting in the human EEG. © The Author 2006. Published by Oxford University Press. All rights reserved.

239. Halder, P., S. Brem, K. Bucher, S. Boujraf, P. Summers, T. Dietrich, S. Kollias, E. Martin, and D. Brandeis, Electrophysiological and hemodynamic evidence for late maturation of hand power grip and force control under visual feedback. Human Brain Mapping, 2007. 28(1): p. 69-84.

Summary: Several human imaging studies have described the neural network involved in power grip under visual control and the subset of cortical areas within this network that are sensitive to force modulation. As there is behavioral evidence for late maturation in even simple hand motor tasks involving visual feedback, we aimed at identifying the neural correlates of these developmental changes. Subjects from three developmental age groups (9-11, 15-17, and adults) performed the same power grip task in both a functional magnetic resonance imaging and an event-related potential (ERP) session. Trials started with a visual target indicating whether to squeeze at 20%, 40%, or 75% of their maximum and online visual feedback on the actual amount of force was provided. Longer reaction times and more shallow slopes of the force curve characterized the behavior of the younger age groups, especially the children. Both neurophysiological methods detected both general as well as force modulation-specific maturational changes. General development was characterized by decreasing ERP amplitudes and increasing deactivation of an extended network, closely resembling the so-called "default" network. The most pronounced developmental changes specific for force control were observed in an ERP component and brain regions involved in feedback processing. In contrast to adult subjects, we found evidence for a stronger dependency on visual feedback information in the younger age groups. Our results also suggest that the ability to deactivate task-irrelevant networks might be a late developmental achievement. © 2006 Wiley-Liss, Inc.

240. Grau, C., L. Fuentemilla, and J. Marco-Pallarés, Functional neural dynamics underlying auditory event-related N1 and N1 suppression response. NeuroImage, 2007. 36(3): p. 522-531.

Summary: Presenting tone triplets of identical stimuli preceded by silent intervals of 30 s produces a series of three N1 averaged event-related potentials (ERPs), the first being of greater amplitude (non-suppressed N1) than the second and third ones (suppressed N1). Maximal statistically independent components (ICs) of single-trial multi-electrode scalp EEG responses to triplets were obtained by ICA algorithm, and then each IC was searched for underlying brain structures by LORETA inverse solution, and for oscillatory contributions by time-frequency analysis. Non-suppressed N1 cortical mechanisms were broken down into five ICs, grouped in two time-windows (early-onset and late-onset) involving the participation of temporal, frontal and parietal structures, and sub-serving EEG oscillatory contributions of power enhancement and putative phase concentration of mainly theta, alpha and low beta bands. Suppressed N1 was due to the modulation of two above-mentioned early-onset ICs, involving temporal structures only, and mainly sub-serving oscillatory contributions of phase concentration of theta and alpha. Present results, showing quantifiable changes of IC descriptors - i.e. time window of activation, implied structures and oscillatory contributions - extracted from two distinct brain functional situations (non-suppressed versus suppressed N1), give support to the view that ICA is not merely a statistical "latent variables" model when applied to ERPs, but could help to capture underlying specific function subunits of brain dynamics. © 2007 Elsevier Inc. All rights reserved.

241. Gómez, C.M., A. Flores, and A. Ledesma, Fronto-parietal networks activation during the contingent negative variation period. Brain Research Bulletin, 2007. 73(1-3): p. 40-47.

Summary: The preparation for stimuli and responses in which the position and required finger to respond are cued, produces the preparatory activation of the specific neural resources that are going to be needed for the completion of the task. The focus of the present report is to evaluate if the fronto-parietal networks activated in fMRI studies during endogenous attention are also activated during the CNV period using EEG recording. The behavioural responses and 64 EEG channels were recorded during an S1-S2 paradigm similar to Posner central cue paradigms. The LORETA analysis based in the averaging of the z-LORETA values showed that the Brodmann's areas with the highest activation during the CNV period were in the medial and superior frontal areas, fronto-parietal lateral areas (including the premotor cortex) and extrastriate visual cortex. These results suggest that in addition to the previously described activation in premotor-motor, posterior sensory and superior and medial frontal areas, the activation of fronto-parietal networks is a main contributor to the CNV, indicating the endogenous attentional effort during the CNV period. © 2007 Elsevier Inc. All rights reserved.

242. Gianotti, L.R.R., G. Künig, D. Lehmann, P.L. Faber, R.D. Pascual-Marqui, K. Kochi, and U. Schreiter-Gasser, Correlation between disease severity and brain electric LORETA tomography in Alzheimer's disease. Clinical Neurophysiology, 2007. 118(1): p. 186-196.

Summary: Objective: To compare EEG power spectra and LORETA-computed intracortical activity between Alzheimer's disease (AD) patients and healthy controls, and to correlate the results with cognitive performance in the AD group. Methods: Nineteen channel resting EEG was recorded in 21 mild to moderate AD patients and in 23 controls. Power spectra and intracortical LORETA tomography were computed in seven frequency bands and compared between groups. In the AD patients, the EEG results were correlated with cognitive performance (Mini Mental State Examination, MMSE). Results: AD patients showed increased power in EEG delta and theta frequency bands, and decreased power in alpha2, beta1, beta2 and beta3. LORETA specified that increases and decreases of power affected different cortical areas while largely sparing prefrontal cortex. Delta power correlated negatively and alpha1 power positively with the AD patients' MMSE scores; LORETA tomography localized these correlations in left temporo-parietal cortex. Conclusions: The non-invasive EEG method of LORETA localized pathological cortical activity in our mild to moderate AD patients in agreement with the literature, and yielded striking correlations between EEG delta and alpha1 activity and MMSE scores in left temporo-parietal cortex. Significance: The present data support the hypothesis of an asymmetrical progression of the Alzheimer's disease. © 2006 International Federation of Clinical Neurophysiology.

243. Giabbiconi, C.M., N.J. Trujillo-Barreto, T. Gruber, and M.M. Müller, Sustained spatial attention to vibration is mediated in primary somatosensory cortex. NeuroImage, 2007. 35(1): p. 255-262.

Summary: Focusing attention to a specific body location has been shown to improve processing of events presented at this body location. One important debate concerns the stage in the somatosensory pathway at which the neural response is modulated when one attends to a tactile stimulus. Previous studies focused on components of the somatosensory evoked potential to transient stimuli, and demonstrated an early cortical attentional modulation. The neural basis of sustained spatial stimulus processing with continuous stimulation remains, however, largely unexplored. A way to approach this topic is to present vibrating stimuli with different frequencies for several seconds simultaneously to different body locations while subjects have to attend to the one or the other location. The amplitude of the somatosensory steady-state evoked potential (SSSEP) elicited by these vibrating stimuli increases with attention. On the basis of 128 electrode recordings, we investigated the topographical distribution and the underlying cortical sources by means of a VARETA approach of this attentional amplitude modulation of the SSSEP. Sustained spatial attention was found to be mediated in primary somatosensory cortex with no differences in SSSEP amplitude topographies between attended and unattended body locations. These result patterns were seen as evidence for a low-level sensory gain control mechanism in tactile spatial attention. © 2006 Elsevier Inc. All rights reserved.

244. Gallinat, J., T. Götz, P. Kalus, M. Bajbouj, T. Sander, and G. Winterer, Genetic variations of the NR3A subunit of the NMDA receptor modulate prefrontal cerebral activity in humans. Journal of Cognitive Neuroscience, 2007. 19(1): p. 59-68.

Summary: Introduction: Recently, a novel N-methyl-D-aspartate (NMDA) receptor subunit, NR3A, has been discovered in the brain. This subunit decreases NMDA receptor activity by modulating the calcium permeability of the receptor channel and current density in cortical cells. Because the NR3A is expressed in the human prefrontal cortex, we hypothesized that genetic variations of the NR3A subunit modulate prefrontal activation. Methods: Electromagnetic activity during selective attention (auditory odd-ball task with target processing) was measured in 281 healthy subjects. Genotyping of a missense variation (rs10989591, Val362Met) of the NR3A gene was performed. Results: Individuals carrying Val/Val genotype showed significantly reduced frontal P300 amplitudes compared with Met/Met subjects. Subsequent low-resolution electromagnetic source analysis revealed that this group difference is likely caused by reduced activation in the inferior frontal gyrus. Conclusions: It was shown for the first time that the genetic constitution of the subunit composition of NMDA receptor regulation might be relevant for prefrontal information processing in humans. The results underline the pivotal role of glutamate in frontal lobe function and indicate that the NR3A subunit could be a plausible candidate gene for diseases with prefrontal dysfunctions. © 2007 Massachusetts Institute of Technology.

245. Freunberger, R., W. Klimesch, P. Sauseng, B. Griesmayr, Y. Höller, T. Pecherstorfer, and S. Hanslmayr, Gamma oscillatory activity in a visual discrimination task. Brain Research Bulletin, 2007. 71(6): p. 593-600.

Summary: We tested the hypothesis whether images of real objects elicit stronger gamma (>25 Hz) synchronization, when compared with scrambled objects. The background of this study is a recent debate about the functional meaning of evoked and induced gamma oscillations. Brain electrical source analysis (BESA) and low resolution electromagnetic tomography analysis (LORETA) was performed on the basis of the event-related potential (ERP) data. A component at around 230 ms (termed C230) showed strongest differences between objects and scrambled objects. Time-frequency analyses were run across electrodes and within the dipole sources. We found increased gamma event-related synchronization (ERS) between 200 and 300 ms for real objects. This effect was strongest in a fronto-medial source. Induced gamma, as also shown in previous studies, reflects the more task-relevant mechanism where object representations become activated. © 2006 Elsevier Inc. All rights reserved.

246. Ferri, R., F. Rundo, O. Bruni, M.G. Terzano, and C.J. Stam, Small-world network organization of functional connectivity of EEG slow-wave activity during sleep. Clinical Neurophysiology, 2007. 118(2): p. 449-456.

Summary: Objective: To analyze the functional connectivity patterns of the EEG slow-wave activity during the different sleep stages and Cyclic Alternating Pattern (CAP) conditions, using concepts derived from Graph Theory. Methods: We evaluated spatial patterns of EEG slow-wave synchronization between all possible pairs of electrodes (19) placed over the scalp of 10 sleeping healthy young normal subjects using two graph theoretical measures: the clustering coefficient (Cp) and the characteristic path length (Lp). The measures were obtained during the different sleep stages and CAP conditions from the real EEG connectivity networks and randomized control (surrogate) networks (Cp-s and Lp-s). Results: Cp and Cp/Cp-s increased significantly from wakefulness to sleep while Lp and Lp/Lp-s did not show changes. Cp/Cp-s was higher for A1 phases, compared to B phases of CAP. Conclusions: The network organization of the EEG slow-wave synchronization during sleep shows features characteristic of small-world networks (high Cp combined with low Lp); this type of organization is slightly but significantly more evident during the CAP A1 subtypes. Significance: Our results show feasibility of using graph theoretical measures to characterize the complexity of brain networks during sleep and might indicate sleep, and the A1 phases of CAP in particular, as a period during which slow-wave synchronization shows optimal network organization for information processing. © 2006 International Federation of Clinical Neurophysiology.

247. Fehmi, L.G. and T. Collura, Effects of electrode placement upon EEG biofeedback training: The monopolar-bipolar controversy. Journal of Neurotherapy, 2007. 11(2): p. 45-63.

Summary: Roles of tradition, convenience, and noise or artifact rejection are discussed with regard to the referential versus bipolar electrode placement controversy in electroencephalography (EEG). Particular emphasis is placed on the relevance to neurofeedback. The crucial interactions between the differential amplifier, brain waves, and referential/bipolar placements are discussed. Through logical analysis and empirical observation, it is demonstrated how the very nature of the EEG differential amplifier must destroy those elements of brain activity which are common (synchronous) to the recording electrodes. Controlled experiments further illustrate the critical importance of electrode placements. Various methods, including preferred electrode placements, are presented to help resolve recording problems that frequently arise. It is concluded that there are serious implications for researchers, EEG clinicians, neurofeedback providers, and their clients in preferring one type of electrode placement technique over another. EEG recording information is affected by this choice. © 2007 by The Haworth Press, Inc. All rights reserved.

248. Ehlis, A.C., A. Reif, M.J. Herrmann, K.P. Lesch, and A.J. Fallgatter, Impact of catechol-O-methyltransferase on prefrontal brain functioning in schizophrenia spectrum disorders. Neuropsychopharmacology, 2007. 32(1): p. 162-170.

Summary: The enzyme catechol-O-methyltransferase (COMT) has attracted increasing interest regarding a genetic disposition towards schizophrenias and as a modulator of prefrontal brain function. A common SNP in the COMT gene causes a Val to Met transition at AA158/AA108 (Val158Met), resulting in reduced COMT activity in Met allele carriers. An impact of COMT genotype on cognition has been well established; however, the exact nature of this influence has yet to be elucidated. The aim of this study was to determine whether COMT genotype affects an electrophysiological marker of prefrontal activation and neuropsychological frontal lobe measures in schizophrenia. To this end, 56 acutely psychotic in-patients with schizophrenia spectrum disorders were investigated. Patients with the COMT 1947AA (Met/Met) genotype (n=13) were compared to a carefully matched sample of patients with a G1947A (Val/Met) genotype (n=15); matching criteria included patients' age, handedness, gender distribution, diagnosis, and medication status. A small group of six homozygous Val allele carriers was additionally included to allow an assessment of possible gene-dosage effects. P300 amplitudes and latencies, as well as an electrophysiological marker of prefrontal brain function (NoGo-Anteriorization/ NGA) and neuropsychological measures (Stroop Test, Verbal Fluency, Trail Making Test) were regarded. Homozygous Met allele carriers had significantly increased NGA values and fronto-central Nogo amplitudes compared to patients with at least one Val allele. They also tended to perform better in the Stroop task, as compared to the matched group of Val/Met patients. These results indicate that COMT genotype exerts a strong impact on prefrontal functioning and executive control in schizophrenia spectrum disorders. © 2007 Nature Publishing Group All rights reserved.

249. Ehlis, A.C., M.J. Herrmann, P. Pauli, G. Stoeber, B. Pfuhlmann, and A.J. Fallgatter, Improvement of prefrontal brain function in endogenous psychoses under atypical antipsychotic treatment. Neuropsychopharmacology, 2007. 32(8): p. 1669-1677.

Summary: Typical and atypical antipsychotics are thought to exert their effects on different neurotransmitter pathways with specific action of atypical compounds on the prefrontal cortex, but studies directly investigating the effect of those drugs on neurophysiological measures of prefrontal brain function are sparse. We therefore investigated the influence of different antipsychotics on an electrophysiological marker of prefrontal brain function (NoGo anteriorization, NGA) and neuropsychological test scores. For this purpose, 38 patients with endogenous psychoses were investigated at the beginning of a stationary psychiatric treatment and at a 6-week-follow-up. Patients were treated with typical or atypical antipsychotics, or a combination of both. They underwent psychopathological diagnostic and neuropsychological testing, as well as electrophysiological investigations during a Continuous Performance Test. The results indicate that typical and atypical antipsychotics differentially affected the development of the NGA over the course of the treatment, typical antipsychotics tending to result in decreased values at follow-up, and atypical antipsychotics stabilizing, or increasing this parameter. Performance in tests of frontal lobe function generally declined under typical antipsychotics and improved with atypical compounds, changes in Stroop interference correlated with changes in the NGA. We conclude that typical and atypical antipsychotics differ regarding their effect on prefrontal brain function in schizophrenia, atypical neuroleptics often showing a more favorable impact than conventional antipsychotics on respective parameters. © 2007 Nature Publishing Group All rights reserved.

250. Duregger, C., H. Bauer, R. Cunnington, G. Lindinger, L. Deecke, W. Lang, G. Dirnberger, and P. Walla, EEG evidence of gender differences in a motor related CNV study. Journal of Neural Transmission, 2007. 114(3): p. 359-366.

Summary: In the present study gender differences related to the contingent negative variation (CNV) were investigated. A series of two acoustic stimuli was presented to participants across a wide age range. The first stimulus was consistent throughout the experiment whereas the second one was either a high frequency or a low frequency tone. One of them had to be answered by a button press (go condition) the other did not require any response (nogo condition). Between the first and the second tone there was a time period of two seconds in which the CNV appeared as a slow negative potential shift. Within this episode data were analysed with respect to gender differences. Statistical analysis revealed topographical differences between men and women in go conditions for both left and right index finger movements. Differences were found over frontal regions where women showed higher brain activity than men and over temporo-parietal regions where men produced higher brain activity than women. In order to explain the fact that only in "go" conditions significant gender differences occurred we introduce the phenomenon of implicit learning. Due to implicit learning assumed predictions related to S2 might have occurred from time to time. This is so, because a 50% chance for one of two different stimuli to occur leads to reasonable assumed predictions after two or more stimuli of a kind occurring in a series. The present data now provide evidence that if such assumed prediction or expectancy is directed towards an upcoming demand to act then brain activity is subject to gender differences. Further studies providing controlled sequences of "go" conditions versus "nogo" conditions have to be done to prove this idea true. © 2006 Springer-Verlag.

251. Ding, L., G.A. Worrell, T.D. Lagerlund, and B. He, Ictal source analysis: Localization and imaging of causal interactions in humans. NeuroImage, 2007. 34(2): p. 575-586.

Summary: We propose a new integrative approach to characterize the structure of seizures in the space, time, and frequency domains. Such characterization leads to a new technical development of ictal source analysis for the presurgical evaluation of epilepsy patients. The present new ictal source analysis method consists of three parts. First, a three-dimensional source scanning procedure is performed by a spatio-temporal FINE source localization method to locate the multiple sources responsible for the time evolving ictal rhythms at their onsets. Next, the dynamic behavior of the sources is modeled by a multivariate autoregressive process (MVAR). Lastly, the causal interaction patterns among the sources as a function of frequency are estimated from the MVAR modeling of the source temporal dynamics. The causal interaction patterns indicate the dynamic communications between sources, which are useful in distinguishing the primary sources responsible for the ictal onset from the secondary sources caused by the ictal propagation. The present ictal analysis strategy has been applied to a number of seizures from five epilepsy patients, and their results are consistent with observations from either MRI lesions or SPECT scans, which indicate its effectiveness. Each step of the ictal source analysis is statistically evaluated in order to guarantee the confidence in the results. © 2006 Elsevier Inc. All rights reserved.

252. Ding, L., C. Wilke, B. Xu, X. Xu, W. Van Drongelen, M. Kohrman, and B. He, EEG source imaging: Correlating source locations and extents with electrocorticography and surgical resections in epilepsy patients. Journal of Clinical Neurophysiology, 2007. 24(2): p. 130-136.

Summary: It is desirable to estimate epileptogenic zones with both location and extent information from noninvasive EEG. In the present study, the authors use a subspace source localization method (FINE), combined with a local thresholding technique, to achieve such tasks. The performance of this method was evaluated in interictal spikes from three pediatric patients with medically intractable partial epilepsy. The thresholded subspace correlation, which is obtained from FINE scanning, is a favorable marker, which implies the extents of current sources associated with epileptic activities. The findings were validated by comparing the results with invasive electrocorticographic (ECoG) recordings of interictal spike activity. The surgical resections in these three patients correlated well with the epileptogenic zones identified from both EEG sources and ECoG potential distributions. The value of the proposed noninvasive technique for estimating epileptiform activity was supported by satisfactory surgery outcomes. Copyright © 2007 American Clinical Neurophysiology Society.

253. Ding, L. and B. He, Sparse source imaging in EEG. Proc. of 2007 Joint Meet. of the 6th Int. Symp. on Noninvasive Functional Source Imaging of the Brain and Heart and the Int. Conf. on Functional Biomedical Imaging, NFSI and ICFBI 2007, 2007: p. 20-23.

Summary: We have developed a new L1-norm based minimum norm estimate (MNE), which is termed as sparse source imaging (SSI). The new SSI algorithm corrects inaccurate orientation discrepancy in previously reported L1-norm MNEs. A new solver to the newly developed SSI has been adopted and known as the second order cone programming (SOCP). The new SSI is assessed by a series of computer simulations. The performance of SSI is compared with other L1-norm MNEs by evaluating the localization error and orientation error. The present simulation results indicate that the new SSI has significantly improved performance, especially in the metric of orientation error. The previously reported L1-norm MNEs show large orientation errors due to the orientation discrepancy. The new SSI algorithm is also applicable to MEG source imaging. © 2007 IEEE.

254. Deouell, L.Y., The frontal generator of the mismatch negativity revisited. Journal of Psychophysiology, 2007. 21(3-4): p. 188-203.

Summary: The mismatch negativity (MMN) is an event-related brain potential elicited by the occurrence of a rare event (deviance) in an otherwise regular acoustic environment, and is assumed to reflect apreattentive mechanism for change detection. A widely adopted model holds that MMN has main generators in the superior temporal planes bilaterally, which are responsible for the sensory memory part of change detection, as well as frontal lobe sources responsible for triggering an attention shift upon change detection. Whereas the temporal sources have been documented in numerous studies across species and methodologies, much less is known about the frontal sources. The present review examines the current state of the evidence for their existence, location, and possible function. It confirms that the frontal generator is still a less consistent finding in MMN research than the temporal generator. There is clear evidence from scalp EEG and, especially, current source density studies for the existence of an MMN generator that is functionally distinct from the main supratemporal generator of the MMN. Evidence from fMRI, PET, optical imaging, EEG source imaging, and lesion studies implicates mainly the inferior frontal and possibly also the medial frontal cortex. However, these results should be taken with caution because of the paucity of support from more direct measures like intracranial recordings and MEG, and the negative findings from several fMRI and PET, as well as EEG source imaging studies. Recent studies also raise questions about the exact role of the frontal generator in triggering an attention shift. Delineating the exact cortical locations of frontal MMN generators, the conditions under which they are activated and. consequently, their function, remains an acute challenge. © 2007 Federation of European Psychophysiology Societies.

255. Delorme, A., M. Westerfield, and S. Makeig, Medial prefrontal theta bursts precede rapid motor responses during visual selective attention. Journal of Neuroscience, 2007. 27(44): p. 11949-11959.

Summary: After visual target stimuli presented infrequently at a covertly attended location, quicker speeded button presses immediately followed a larger positive (P3f) ramp in averaged electroencephalographic (EEG) recordings from the forehead. We show this peak in the mean response time locked to the button press to be principally composed of triphasic, primarily low-theta band (4.5 Hz) complexes preceding but only partially phase-locked to the button press, with larger complexes preceding quicker motor responses. For 10 of 15 subjects, independent component analysis of the unaveraged 31-channel data identified a temporally independent medial frontal EEG process contributing to these phenomena. Low-resolution tomographic modeling localized related components of two 253-channel data sets to medial frontal polar cortex (BA32/10). The far-frontal low-theta complexes and concomitant mean P3f positivity may index cortical activity induced by paralimbic processes involved in disinhibiting impulsive motor responses to rewarding or goal-fulfilling stimuli or events. Copyright © 2007 Society for Neuroscience.

256. Deboer, T., Technologies of sleep research. Cellular and Molecular Life Sciences, 2007. 64(10): p. 1227-1235.

Summary: Sleep is investigated in many different ways, many different species and under many different circumstances. Modern sleep research is a multidisciplinary venture. Therefore, this review cannot give a complete overview of all techniques used in sleep research and sleep medicine. What it will try to do is to give an overview of widely applied techniques and exciting new developments. Electroencephalography has been the backbone of sleep research and sleep medicine since its first application in the 1930s. The electroencephalogram is still used but now combined with many different techniques monitoring body and brain temperature, changes in brain and blood chemistry, or changes in brain functioning. Animal research has been very important for progress in sleep research and sleep medicine. It provides opportunities to investigate the sleeping brain in ways not possible in healthy volunteers. Progress in genomics has brought new insights in sleep regulation, the best example being the discovery of hypocretin/orexin deficiency as the cause of narcolepsy. Gene manipulation holds great promise for the future since it is possible not only to investigate the functions of different genes under normal conditions, but also to mimic human pathology in much greater detail. © 2007 Birkhäuser Verlag.

257. De Vos, M., L. De Lathauwer, B. Vanrumste, S. Van Huffel, and W. Van Paesschen, Canonical decomposition of ictal scalp EEG and accurate source localisation: Principles and simulation study. Computational Intelligence and Neuroscience, 2007. 2007.

Summary: Long-term electroencephalographic (EEG) recordings are important in the presurgical evaluationof refractory partial epilepsy for the delineation of the ictal onset zones. In this paper, we introduce a new concept for an automatic, fast, and objective localisation of the ictal onset zone in ictal EEG recordings. Canonical decomposition of ictal EEG decomposes the EEG in atoms. One or more atoms are related to the seizure activity. A single dipole was then fitted to model the potential distribution of each epileptic atom. In this study, we performed a simulation study in order to estimate the dipole localisation error. Ictal dipole localisation was very accurate, even at low signal-to-noise ratios, was not affected by seizure activity frequency or frequency changes, and was minimally affected by the waveform and depth of the ictal onset zone location. Ictal dipole localisation error using 21 electrodes was around 10.0 mm andimproved more than tenfold in the range of 0.5-1.0 mm using 148 channels. In conclusion, oursimulation study of canonical decomposition of ictal scalp EEG allowed a robust and accuratelocalisation of the ictal onset zone.

258. de Tommaso, M., O. Difruscolo, V. Sciruicchio, N. Specchio, and P. Livrea, Abnormalities of the contingent negative variation in Huntington's disease: Correlations with clinical features. Journal of the Neurological Sciences, 2007. 254(1-2): p. 84-89.

Summary: The contingent negative variation (CNV) is a neurophysiological pattern related to planning of external - paced, voluntary movements. The aim of the study, was to examine the CNV in a cohort of mild demented and non-medicated HD patients, evaluating the CNV amplitude modifications in the light of clinical features and performing Low Resolution Brain Electromagnetic Tomography (LORETA) analysis in order to show the CNV multiple generators. Fourteen HD patients and 25 sex and age-matched controls were studied. All subjects were evaluated by the motor section of UHDRS, MMSE and WAIS. The CNV was recorded by 19 scalp electrodes, with a red light flash as visual warning stimulus (S1), followed by a blue light flash (S2) after a fixed interval of 3 s. The amplitude of early CNV was significantly reduced in HD, compared to controls: the amplitude reduction was significantly correlated with the bradikinesia score. LORETA analysis of early CNV significantly discriminated patients from controls, for a prevalent activation of the posterior part of anterior cingulate cortex in HD. An abnormal activation of the associative cortex devoted to the processing of attention preceding voluntary movement may be supposed in HD, probably mediated by the altered basal ganglia modulation. © 2007 Elsevier B.V. All rights reserved.

259. Daunizeau, J., C. Grova, G. Marrelec, J. Mattout, S. Jbabdi, M. Pélégrini-Issac, J.M. Lina, and H. Benali, Symmetrical event-related EEG/fMRI information fusion in a variational Bayesian framework. NeuroImage, 2007. 36(1): p. 69-87.

Summary: In this work, we propose a symmetrical multimodal EEG/fMRI information fusion approach dedicated to the identification of event-related bioelectric and hemodynamic responses. Unlike existing, asymmetrical EEG/fMRI data fusion algorithms, we build a joint EEG/fMRI generative model that explicitly accounts for local coupling/uncoupling of bioelectric and hemodynamic activities, which are supposed to share a common substrate. Under a dedicated assumption of spatio-temporal separability, the spatial profile of the common EEG/fMRI sources is introduced as an unknown hierarchical prior on both markers of cerebral activity. Thereby, a devoted Variational Bayesian (VB) learning scheme is derived to infer common EEG/fMRI sources from a joint EEG/fMRI dataset. This yields an estimate of the common spatial profile, which is built as a trade-off between information extracted from EEG and fMRI datasets. Furthermore, the spatial structure of the EEG/fMRI coupling/uncoupling is learned exclusively from the data. The proposed data generative model and devoted VBEM learning scheme thus provide an un-supervised well-balanced approach for the fusion of EEG/fMRI information. We first demonstrate our approach on synthetic data. Results show that, in contrast to classical EEG/fMRI fusion approach, the method proved efficient and robust regardless of the EEG/fMRI discordance level. We apply the method on EEG/fMRI recordings from a patient with epilepsy, in order to identify brain areas involved during the generation of epileptic spikes. The results are validated using intracranial EEG measurements. © 2007 Elsevier Inc. All rights reserved.

260. Daunizeau, J. and K.J. Friston, A mesostate-space model for EEG and MEG. NeuroImage, 2007. 38(1): p. 67-81.

Summary: We present a multi-scale generative model for EEG, that entails a minimum number of assumptions about evoked brain responses, namely: (1) bioelectric activity is generated by a set of distributed sources, (2) the dynamics of these sources can be modelled as random fluctuations about a small number of mesostates, (3) mesostates evolve in a temporal structured way and are functionally connected (i.e. influence each other), and (4) the number of mesostates engaged by a cognitive task is small (e.g. between one and a few). A Variational Bayesian learning scheme is described that furnishes the posterior density on the models parameters and its evidence. Since the number of meso-sources specifies the model, the model evidence can be used to compare models and find the optimum number of meso-sources. In addition to estimating the dynamics at each cortical dipole, the mesostate-space model and its inversion provide a description of brain activity at the level of the mesostates (i.e. in terms of the dynamics of meso-sources that are distributed over dipoles). The inclusion of a mesostate level allows one to compute posterior probability maps of each dipole being active (i.e. belonging to an active mesostate). Critically, this model accommodates constraints on the number of meso-sources, while retaining the flexibility of distributed source models in explaining data. In short, it bridges the gap between standard distributed and equivalent current dipole models. Furthermore, because it is explicitly spatiotemporal, the model can embed any stochastic dynamical causal model (e.g. a neural mass model) as a Markov process prior on the mesostate dynamics. The approach is evaluated and compared to standard inverse EEG techniques, using synthetic data and real data. The results demonstrate the added-value of the mesostate-space model and its variational inversion. © 2007 Elsevier Inc. All rights reserved.

261. Darvas, F. and R.M. Leahy, Functional imaging of brain activity and connectivity with MEG. Understanding Complex Systems, 2007. 2007: p. 201-219.

Summary: We present a survey of imaging and signal processing methods that use data from magnetoencephalographic (MEG) or electroencephalographic (EEG) measurements to produce spatiotemporal maps of neuronal activity as well as measures of functional connectivity between active brain regions. During the course of the chapter, we give a short introduction to the basic bioelectromagnetic inverse problem and present a number of methods that have been developed to solve this problem. We discuss methods to address the statistical relevance of inverse solutions, which is especially important if imaging methods are used to compute the inverse. For such solutions, permutation methods can be used to identify regions of interest, which can subsequently be used for the analysis of functional connectivity. The third section of the chapter reviews a collection of methods commonly used in EEG and MEG connectivity analysis, emphasizing their restrictions and advantages and their applicability to time series extracted from inverse solutions.

262. Cottereau, B., K. Jerbi, and S. Baillet, Multiresolution imaging of MEG cortical sources using an explicit piecewise model. NeuroImage, 2007. 38(3): p. 439-451.

Summary: Imaging neural generators from MEG magnetic fields is often considered as a compromise between computationally-reasonable methodology that usually yields poor spatial resolution on the one hand, and more sophisticated approaches on the other hand, potentially leading to intractable computational costs. We approach the problem of obtaining well-resolved source images with unexcessive computation load with a multiresolution image model selection (MiMS) technique. The building blocks of the MiMS source model are parcels of the cortical surface which can be designed at multiple spatial resolutions with the combination of anatomical and functional priors. Computation charge is reduced owing to 1) compact parametric models of the activation of extended brain parcels using current multipole expansions and 2) the optimization of the generalized cross-validation error on image models, which is closed-form for the broad class of linear estimators of neural currents. Model selection can be complemented by any conventional imaging approach of neural currents restricted to the optimal image support obtained from MiMS. The estimation of the location and spatial extent of brain activations is discussed and evaluated using extensive Monte-Carlo simulations. An experimental evaluation was conducted with MEG data from a somatotopic paradigm. Results show that MiMS is an efficient image model selection technique with robust performances at realistic noise levels. © 2007 Elsevier Inc. All rights reserved.

263. Cohen, M.X. and C. Ranganath, Reinforcement learning signals predict future decisions. Journal of Neuroscience, 2007. 27(2): p. 371-378.

Summary: Optimal behavior in a competitive world requires the flexibility to adapt decision strategies based on recent outcomes. In the present study, we tested the hypothesis that this flexibility emerges through a reinforcement learning process, in which reward prediction errors are used dynamically to adjust representations of decision options. We recorded event-related brain potentials (ERPs) while subjects played a strategic economic game against a computer opponent to evaluate how neural responses to outcomes related to subsequent decision-making. Analyses of ERP data focused on the feedback-related negativity (FRN), an outcome-locked potential thought to reflect a neural prediction error signal. Consistent with predictions of a computational reinforcement learning model, we found that the magnitude of ERPs after losing to the computer opponent predicted whether subjects would change decision behavior on the subsequent trial. Furthermore, FRNs to decision outcomes were disproportionately larger over the motor cortex contralateral to the response hand that was used to make the decision. These findings provide novel evidence that humans engage a reinforcement learning process to adjust representations of competing decision options. Copyright © 2007 Society for Neuroscience.

264. Clemens, B., M. Bessenyei, P. Piros, M. Tóth, L. Seress, and I. Kondákor, Characteristic distribution of interictal brain electrical activity in idiopathic generalized epilepsy. Epilepsia, 2007. 48(5): p. 941-949.

Summary: Purpose: To demonstrate the anatomic localization of the cortical sources of the interictal EEG activity in human idiopathic generalized epilepsy (IGE). Methods: Multiple cortical and hippocampal sources of the interictal spontaneous EEG activity were investigated by low-resolution electromagnetic tomography in 15 untreated IGE patients and in 15 healthy controls. EEG activity (current density) in four frequency bands (delta: 1.5-3.5 Hz, theta: 3.5-7.5 Hz, alpha: 7.5-12.5 Hz, beta: 12.5-25.0 Hz) was computed for 2,397 voxels. Voxel-by-voxel group comparison was done between the patient and the control group. Voxels with p < 0.01 differences (between the two groups) were correlated with cortical anatomy. Results: Areas of significantly increased or decreased activity were characterized by their anatomical extension and the frequency bands involved. Five areas of bilaterally increased activity were found: rostral part of the prefrontal cortex (delta, theta); posterior part of the insula (delta); hippocampus and mediobasal temporal cortex (all frequency bands); medial parietooccipital cortex (theta, alpha, beta); dorsal and polar parts of the occipital cortex (alpha). Bilaterally decreased delta, theta, alpha activity was found in the majority of the frontal and anterior parietal cortex on the lateral surface, and in parts of the medial surface of the hemispheres. The area of decreased beta activity was less extensive. The right lateral and laterobasal temporal cortex showed decreased delta, theta, alpha, and beta activity, while its left counterpart only showed decreased delta and alpha activity in a limited part of this area. Conclusions: (1) Pathological interictal EEG activity is not evenly distributed across the cortex in IGE. The prefrontal area of increased activity corresponds to the area that is essential in the buildup of the ictal spike-wave paroxysms (absence seizures). The existence of the posterior "center of gravity" of increased EEG activity in IGE was confirmed. The frontal area of decreased activity might be related to the cognitive deficit described in IGE patients. (2) Increased activity in a lot of ontogenetically older areas (including the hippocampi) and decreased activity in the majority of the isocortex is a peculiar pattern that argues for a developmental hypothesis for IGE. © 2007 International League Against Epilepsy.

265. Chen, A., J. Yao, and J.P.A. Dewald, A novel experimental setup combining EEG and robotics to investigate brain activity driving controlled reaching movements in chronic stroke survivors. 2007 IEEE 10th International Conference on Rehabilitation Robotics, ICORR'07, 2007: p. 876-882.

Summary: When chronic, hemiparetic stroke survivors make reaching movements while lifting the paretic arm against gravity, their ability to generate the necessary independent joint movements for reaching degrades dramatically due to abnormal muscle coactivation patterns that couple shoulder abduction with elbow flexion. The neural mechanisms behind the appearance of abnormal coordination patterns during post-stroke recovery are largely unknown, but they are possibly related to a loss in cortical resolution and an increased usage of undamaged, indirect descending motor pathways via the brainstem. In order to investigate the underlying mechanisms for this behavior in chronic stroke survivors, we have developed a novel experimental setup that simultaneously records electroencephalographs (EEG) signals while the test subject makes different reaching movements with an ACT3D robot. This method allows us to map brain activity during controlled reaching movements with different levels of robot-mediated limb support for the first time. Our results provide evidence for changes in cortical activity driving realistic upperextremity reaching movements as independent joint control becomes compromised in stroke survivors. © 2007 IEEE.

266. Carretié, L., J.A. Hinojosa, S. López-Martín, and M. Tapia, An electrophysiological study on the interaction between emotional content and spatial frequency of visual stimuli. Neuropsychologia, 2007. 45(6): p. 1187-1195.

Summary: Previous studies suggest that the magnocellular pathway, a visual processing system that rapidly provides low spatial frequency information to fast-responding structures such as the amygdala, is more involved in the processing of emotional facial expressions than the parvocellular pathway (which conveys all spatial frequencies). The present experiment explored the spatio-temporal characteristics of the spatial frequency modulation of affect-related neural processing, as well as its generalizability to non-facial stimuli. To that aim, the event-related potentials (ERPs) elicited by low-pass filtered (i.e., high spatial frequencies are eliminated) and intact non-facial emotional images were recorded from 31 participants using a 60-electrode array. The earliest significant effect of spatial frequency was observed at 135 ms from stimulus onset: N135 component of the ERPs. In line with previous studies, the origin of N135 was localized at secondary visual areas for low-pass filtered stimuli and at primary areas for intact stimuli. Importantly, this component showed an interaction between spatial frequency and emotional content: within low-pass filtered pictures, negative stimuli elicited the highest N135 amplitudes. By contrast, within intact stimuli, neutral pictures were those eliciting the highest amplitudes. These results suggest that high spatial frequencies are not essential for the initial affect-related processing of visual stimuli, which would mainly rely on low spatial frequency visual information. According to present data, high spatial frequencies would come into play later on. © 2006 Elsevier Ltd. All rights reserved.

267. Cao, N., I.S. Yetik, A. Nehorai, C.H. Muravchik, and J. Haueisen, Parametric surface-source modeling and estimation with electroencephalography. International Congress Series, 2007. 1300: p. 117-120.

Summary: We develop four parametric EEG models to estimate current sources that are spatially distributed on a surface. Such sources exist for example in studies of epilepsy or induced spreading depression. We provide forward and inverse solutions and compute the Cramér-Rao bounds on the unknown source parameters. We validate our solutions using electric measurements from a body phantom. © 2007 Elsevier B.V. All rights reserved.

268. Cannon, R., J. Lubar, M. Congedo, K. Thornton, K. Towler, and T. Hutchens, The effects of neurofeedback training in the cognitive division of the anterior cingulate gyrus. International Journal of Neuroscience, 2007. 117(3): p. 337-357.

Summary: This study examines the efficacy of neurofeedback training in the cognitive division of the anterior cingulate gyrus and describes its relationship with cortical regions known to be involved in executive functions. This study was conducted with eight non-clinical students, four male and four female, with a mean age of twenty-two. Learning occurred in the ACcd at significant levels over sessions and in the anterior regions that receive projections from the AC. There appears to be a multidimensional executive circuit that increases in the same frequency in apparent synchrony with the AC and it may be possible to train this sub-cortical region using LNFB. Copyright © 2007 Informa Healthcare.

269. Brookes, M.J., C.M. Stevenson, G.R. Barnes, A. Hillebrand, M.I.G. Simpson, S.T. Francis, and P.G. Morris, Beamformer reconstruction of correlated sources using a modified source model. NeuroImage, 2007. 34(4): p. 1454-1465.

Summary: This paper introduces a lead field formulation for use in beamformer analysis of MEG data. This 'dual source beamformer' is a technique to image two temporally correlated sources using beamformer methodology. We show that while the standard, single source beamformer suppresses the reconstructed power of two spatially separate but temporally correlated sources, the dual source beamformer allows for their accurate reconstruction. The technique is proven to be accurate using simulations. We also show that it can be used to image accurately the auditory steady state response, which is correlated between the left and right auditory cortices. We suggest that this technique represents a useful way of locating correlated sources, particularly if a seed location can be defined a priori for one of the two sources. Such a priori information could be based on previous studies using similar paradigms, or from other functional neuroimaging techniques. © 2006 Elsevier Inc. All rights reserved.

270. Bolstad, A.K., B.D. Van Veen, and R.D. Nowak, Space-time sparsity regularisation for the magnetoencephalography inverse problem. 2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro - Proceedings, 2007: p. 984-987.

Summary: The concept of "Space-Time Sparsity" (STS) penalization is introduced for solving the magnetoencephalography (MEG) inverse problem. The STS approach assumes that events of interest occur on localized areas of the cortex over a limited time duration, and that only a few events of interest occur during a measurement period (or epoch). Cortical activity is reconstructed by minimizing a cost function which fits the data with a sparse set of space-time events using a novel expectation-maximization (EM) algorithm. We employ spatial and temporal basis functions to reduce the dimension of the data fitting problem and combat noise. Simulations suggest that our approach could be useful for identifying sequential relationships in the brain. © 2007 IEEE.

271. Blum, J., K. Lutz, and L. Jäncke, Coherence and phase locking of intracerebral activation during visuo- and audio-motor learning of continuous tracking movements. Experimental Brain Research, 2007. 182(1): p. 59-69.

Summary: The aim of the present study was to assess changes in EEG coherence and phase locking between fronto-parietal areas, including the frontal and parietal motor areas, during early audio- and visuo-motor learning of continuous tracking movements. Subjects learned to turn a steering-wheel according to a given trajectory in order to minimise the discrepancy between a changing foreground stimulus (controllable by the subjects) and a constant background stimulus (uncontrollable) for both the auditory and the visual modality. In the auditory condition, we uncovered a learning-related increase in inter-hemispheric phase locking between inferior parietal regions, suggesting that coupling between areas involved in audiomotor integration is augmented during early learning stages. Intra-hemispheric phase locking between motor and superior parietal areas increased in the left hemisphere as learning progressed, indicative of integrative processes of spatial information and movement execution. Further tests show a significant correlation of intra-hemispheric phase locking between the motor and the parietal area bilaterally and movement performance in the visual condition. These results suggest that the motor-parietal network is operative in the auditory and in the visual condition. This study confirms that a complex fronto-parietal network subserves learning of a new movement that requires sensorimotor transformation and demonstrates the importance of interregional coupling as a neural correlate for successful acquisition and implementation of externally guided behaviour. © 2007 Springer-Verlag.

272. Béla, C., B. Mónika, T. Márton, and K. István, Valproate selectively reduces EEG activity in anterior parts of the cortex in patients with idiopathic generalized epilepsy. A low resolution electromagnetic tomography (LORETA) study. Epilepsy Research, 2007. 75(2-3): p. 186-191.

Summary: Purpose: To localize the cortical area where the anticonvulsive drug valproate (VPA) exerts its effect in patients with idiopathic generalized epilepsy (IGE). Methods: In a prior study we investigated 15 IGE patients in the untreated condition and compared their low resolution electromagnetic tomography (LORETA) results to a normal control group. The investigation of these patients was continued in the present study. All the 15 patients were treated with VPA and were followed by the authors. EEG was recorded after 3 months of VPA treatment in the seizure-free patients. A total of 2 min of 19-channels, common reference-recorded, waking-relaxed background activity (without paroxysmal and other, non-stationary elements) was analyzed. "Activity" (current density, amper/meters squared) was given in four frequency bands (delta, theta, alpha, beta). Band-related group differences between the present LORETA results (treated condition) and the prior LORETA results (untreated condition) were computed for all the 2394 voxels by t-tests for interdependent datasets. The statistically significant (p < 0.01, uncorrected) differences of activity were projected to real cortical anatomy using the Talairach Brain Atlas. Results: Statistically significant differences between the untreated and treated condition emerged in the delta and theta bands. VPA decreased delta and theta activity in the entire frontal cortex, insula, anterior temporal cortex and hippocampus, and in the anterior part of the parietal cortex. Conclusions: VPA decreased activity in parts of the cortex that display ictogenic properties and contribute to seizure generation in IGE. Furthermore, the anatomical distribution of the drug effect exactly corresponded to the VPA-related accumulation of neuroprotective proteins reported in experimental papers. © 2007 Elsevier B.V. All rights reserved.

273. Banaschewski, T. and D. Brandeis, Annotation: What electrical brain activity tells us about brain function that other techniques cannot tell us - A child psychiatric perspective. Journal of Child Psychology and Psychiatry and Allied Disciplines, 2007. 48(5): p. 415-435.

Summary: Background: Monitoring brain processes in real time requires genuine subsecond resolution to follow the typical timing and frequency of neural events. Non-invasive recordings of electric (EEG/ERP) and magnetic (MEG) fields provide this time resolution. They directly measure neural activations associated with a wide variety of brain states and processes, even during sleep or in infants. Mapping and source estimation can localise these time-varying activation patterns inside the brain. Methods: Recent EEG/ERP research on brain functions in the domains of attention and executive functioning, perception, memory, language, emotion and motor processing in ADHD, autism, childhood-onset schizophrenia, Tourette syndrome, specific language disorder and developmental dyslexia, anxiety, obsessive-compulsive disorder, and depression is reviewed. Results: Over the past two decades, electrophysiology has substantially contributed to the understanding of brain functions during normal development, and psychiatric conditions of children and adolescents. Its time resolution has been important to measure covert processes, and to distinguish cause and effect. Conclusion: In the future, EEG/ERP parameters will increasingly characterise the interplay of neural states and information processing. They are particularly promising tools for multilevel investigations of etiological pathways and potential predictors of clinical treatment response. © 2007 The Authors Journal compilation © 2007 Association for Child and Adolescent Mental Health.

274. Bai, X., V.L. Towle, E.J. He, and B. He, Evaluation of cortical current density imaging methods using intracranial electrocorticograms and functional MRI. NeuroImage, 2007. 35(2): p. 598-608.

Summary: Objective: EEG source imaging provides important information regarding the underlying neural activity from noninvasive electrophysiological measurements. The aim of the present study was to evaluate source reconstruction techniques by means of the intracranial electrocorticograms (ECoGs) and functional MRI. Methods: Five source imaging algorithms, including the minimum norm least square (MNLS), LORETA with Lp-norm (p equal to 1, 1.5 and 2), sLORETA, the minimum Lp-norm (p equal to 1 and 1.5; when p = 2, the MNLS method is mathematically equivalent to the minimum Lp-norm) and L1-norm (the linear programming) methods, were evaluated in a group of 10 human subjects, in a paradigm with somatosensory stimulation. Cortical current density (CCD) distributions were estimated from the scalp somatosensory evoked potentials (SEPs), at approximately 30 ms following electrical stimulation of median nerve at the wrist. Realistic geometry boundary element head models were constructed from the MRIs of each subject and used in the CCD analysis. Functional MRI results obtained from a motor task and sensory stimulation in all subjects were used to identify the central sulcus, motor and sensory areas. In three patients undergoing neurosurgical evaluation, ECoGs were recorded in response to the somatosensory stimulation, and were used to help determine the central sulcus and the sensory cortex. Results: The CCD distributions estimated by the Lp-norm and LORETA-Lp methods were smoother when the p values were high. The LORETA based on the L1-norm performed better than the LORETA-L2 method for imaging well localized sources such as the P30 component of the SEP. The mean and standard deviation of the distance between the location of maximum CCD value and the central sulcus, estimated by the minimum Lp-norm (with p equal to 1), L1-norm (the Linear programming) and LORETA-Lp (with p equal to 1) methods, were 4, 7, 7 mm and 3, 4, 2 mm, respectively (after converting into Talairach coordinates). The mean and standard deviation of the aforementioned distance, estimated by the MNLS, LORETA with Lp-norm (p equal to 1.5 and 2.0), sLORETA and the minimum Lp-norm (p equal to 1.5) methods, were over 11 mm and 6 mm, respectively. Conclusions: The present experimental study suggests that L1-norm-based algorithms provide better performance than L2 and L1.5-norm-based algorithms, in the context of CCD imaging of well localized sources induced by somatosensory electrical stimulation of median nerve at the wrist. © 2006 Elsevier Inc. All rights reserved.

275. Astolfi, L., F. De Vico Fallani, F. Cincotti, D. Mattia, M.G. Marciani, S. Bufalari, S. Salinari, A. Colosimo, L. Ding, J.C. Edgar, W. Heller, G.A. Miller, B. He, and F. Babiloni, Imaging functional brain connectivity patterns from high-resolution EEG and fMRI via graph theory. Psychophysiology, 2007. 44(6): p. 880-893.

Summary: We describe a set of computational tools able to estimate cortical activity and connectivity from high-resolution EEG and fMRI recordings in humans. These methods comprise the estimation of cortical activity using realistic geometry head volume conductor models and distributed cortical source models, followed by the evaluation of cortical connectivity between regions of interest coincident with the Brodmann areas via the use of Partial Directed Coherence. Connectivity patterns estimated on the cortical surface in different frequency bands are then imaged and interpreted with measures based on graph theory. These computational tools were applied on a set of EEG and fMRI data from a Stroop task to demonstrate the potential of the proposed approach. The present findings suggest that the methodology is able to identify differences in functional connectivity patterns elicited by different experimental tasks or conditions. Copyright © 2007 Society for Psychophysiological Research.

276. Arzouan, Y., A. Goldstein, and M. Faust, Dynamics of hemispheric activity during metaphor comprehension: Electrophysiological measures. NeuroImage, 2007. 36(1): p. 222-231.

Summary: Brain imaging studies have lead to conflicting findings regarding the involvement of the right hemisphere (RH) in metaphor comprehension. Some report more relative RH activation when processing figurative expressions but others have shown just the opposite. The inconsistencies might be a result of the low temporal resolution related to current brain imaging techniques which is insufficient to uncover patterns of hemispheric interaction that change over time. Event-related potentials and a source estimation technique (LORETA) were used to investigate such temporal interactions when processing two-word expressions denoting literal, conventional metaphoric, and novel metaphoric meaning, as well as unrelated word pairs. Participants performed a semantic judgment task in which they decided whether each word pair conveyed a meaningful expression. Our findings indicate that during comprehension of novel metaphors there are some stages of considerable RH involvement, mainly of the temporal and superior frontal areas. Although the processing mechanisms used for all types of expressions were similar and require both hemispheres, the relative contribution of each hemisphere at specific processing stages depended on stimulus type. Those stages correspond roughly to the N400 and LPC components which reflect semantic and contextual integration, respectively. The present study demonstrates that RH mechanisms are necessary, but not sufficient, for understanding metaphoric expressions. Both hemispheres work in concert in a complex dynamical pattern during literal and figurative language comprehension. Electrophysiological recordings together with source localization algorithms such as LORETA are a viable tool for measuring this type of activity patterns. © 2007 Elsevier Inc. All rights reserved.

277. Zumsteg, D., A.M. Lozano, H.G. Wieser, and R.A. Wennberg, Cortical activation with deep brain stimulation of the anterior thalamus for epilepsy. Clinical Neurophysiology, 2006. 117(1): p. 192-207.

Summary: Objective: We studied the relation between thalamic stimulation parameters and the morphology, topographic distribution and cortical sources of the cerebral responses in patients with intractable epilepsy undergoing deep brain stimulation (DBS) of the thalamus. Methods: Bipolar and monopolar stimuli were delivered at a rate of 2 Hz to the anterior (AN, four patients), the dorsomedian (DM, four patients), and the centromedian nucleus (CM, one patient) using the programmable stimulation device (Medtronic ITREL II). Source modeling was carried out by using statistical non-parametric mapping of low-resolution electromagnetic tomography (LORETA) values. Results: All patients demonstrated reproducible time-locked cortical responses (CRs) consisting of a sequence of components with latencies between 20 and 320 ms. The morphology of these CRs, however, was very heterogeneous, depending primarily on the site of stimulation. Following AN stimulation, cortical activation was most prominent in ipsilateral cingulate gyrus, insular cortex and lateral neocortical temporal structures. Stimulation of the DM mainly showed activation of the ipsilateral orbitofrontal and mesial and lateral frontal areas, but also involvement of mesial temporal structures. Stimulation of the CM showed a rather diffuse (though still mainly ipsilateral) increase of cortical activity. The magnitude of cortical activation was positively related to the strength of the stimulus and inversely related to the impedance of the electrode. Conclusions: The pattern of cortical activation corresponded with the hodology of the involved structures and may underscore the importance of optimal localization of DBS electrodes in patients with epilepsy. Significance: The method of analyzing sources of CRs could potentially be a useful tool for titration of DBS parameters in patients with electrode contacts in clinically silent areas. Furthermore, the inverse relation of the cortical activation and the impedance of the electrode contacts might suggest that these impedance measurements should be taken into consideration when adjusting DBS parameters in patients with epilepsy. © 2005 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

278. Zumsteg, D., A. Friedman, H.G. Wieser, and R.A. Wennberg, Source localization of interictal epileptiform discharges: Comparison of three different techniques to improve signal to noise ratio. Clinical Neurophysiology, 2006. 117(3): p. 562-571.

Summary: Objective: To investigate the localization accuracy of low-resolution electromagnetic tomography (LORETA) for mesial temporal interictal epileptiform discharges (IED) using a new relative averaging (RELAVG) technique for noise reduction. Methods: We analyzed 19 patterns of mesial temporal IED recorded simultaneously with scalp and foramen ovale (FO) electrodes in 15 consecutive patients who underwent presurgical assessment for intractable temporal lobe epilepsy. The scalp signals were time-locked to the peak activity in the FO electrode recordings and source modeling was performed using the RELAVG technique. Random noise of various amounts was then applied. The results were compared to intracranial data obtained from the FO electrode recordings and to LORETA source solutions obtained using two other approaches to improve signal to noise ratio (SNR): statistical non-parametric mapping (SNPM) and the commonly applied averaging (AVG) technique. Results: The RELAVG technique allowed for reasonable mesial temporal localization in 52.6% (10/19) of IED patterns, compared with 73.7% (14/19) using SNPM. The AVG technique provided no strictly mesial temporal solutions. Nine of the IED patterns revealed relative current density quotient changes >10; all of these were accurately localized by RELAVG into mesial temporal structures. Increasing amounts of white and physiological noise had no influence on the accuracy of RELAVG and SNPM solutions, whereas AVG source reconstructions became progressively spurious. Conclusion: The RELAVG technique and SNPM, but not the commonly used AVG technique, allow for reasonable source localization of mesial temporal IED. SNPM is the most accurate but also the most time-consuming noise reduction technique. Significance: The RELAVG LORETA technique might provide a simple and fast semi-quantitative alternative for localizing IED with low single to noise ratio. © 2005 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

279. Zumsteg, D., A. Friedman, H.G. Wieser, and R.A. Wennberg, Propagation of interictal discharges in temporal lobe epilepsy: Correlation of spatiotemporal mapping with intracranial foramen ovale electrode recordings. Clinical Neurophysiology, 2006. 117(12): p. 2615-2626.

Summary: Objective: We have investigated intracerebral propagation of interictal epileptiform discharges (IED) in patients with mesial temporal lobe epilepsy (MTLE) by using spatiotemporal source maps based on statistical nonparametric mapping (SNPM) of low resolution electromagnetic tomography (LORETA) values. Methods: We analyzed 30 patterns of IED recorded simultaneously with scalp and intracranial foramen ovale (FO) electrodes in 15 consecutive patients with intractable MTLE. The scalp EEG signals were averaged time-locked to the peak activity in bilateral 10-contact FO electrode recordings. SNPM was applied to LORETA values and spatiotemporal source maps were created by allocating the t-values over time to their corresponding Brodmann areas. Propagation was defined as secondary statistically significant involvement of distinct cortical areas separated by >15 ms. The results were correlated with intracranial data obtained from FO electrode recordings and with scalp EEG recordings. All patients underwent subsequent amygdalo-hippocampectomy and outcome was assessed one year after surgery. Results: We found mesial to lateral propagation in 6/30 IED patterns (20%, four patients), lateral to mesial propagation in 4/30 IED patterns (13.3%, four patients) and simultaneous (within 15 ms) activation of mesial and lateral temporal areas in 6/30 IED patterns (20%, five patients). Propagation generally occurred within 30 ms and was always limited to ipsilateral cortical regions. Nine/30 IED patterns (30%) showed restricted activation of mesial temporal structures and no significant solutions were found in 5/30 IED patterns (16.7%). There was no clear association between the number or characteristics of IED patterns and the postsurgical outcome. Conclusions: Spatiotemporal mapping of SNPM LORETA accurately describes mesial to lateral temporal propagation of IED, and vice versa, which commonly occur in patients with MTLE. Significance: Intracerebral propagation must be considered when using non-invasive source algorithms in patients with MTLE. Spatiotemporal mapping might be useful for visualizing this propagation. © 2006 International Federation of Clinical Neurophysiology.

280. Zumsteg, D., D.M. Andrade, and R.A. Wennberg, Source localization of small sharp spikes: Low resolution electromagnetic tomography (LORETA) reveals two distinct cortical sources. Clinical Neurophysiology, 2006. 117(6): p. 1380-1387.

Summary: Objective: We have investigated the cortical sources and electroencephalographic (EEG) characteristics of small sharp spikes (SSS) by using statistical non-parametric mapping (SNPM) of low resolution electromagnetic tomography (LORETA). Methods: We analyzed 7 SSS patterns (501 individual SSS) in 6 patients who underwent sleep EEG studies with 29 or 23 scalp electrodes. The scalp signals were averaged time-locked to the SSS peak activity and subjected to SNPM of LORETA values. Results: All 7 SSS patterns (mean 72 individual SSS, range 11-200) revealed a very similar and highly characteristic transhemispheric oblique scalp voltage distribution comprising a first negative field maximum over ipsilateral lateral temporal areas, followed by a second negative field maximum over the contralateral subtemporal region approximately 30 ms later. SNPM-LORETA consistently localized the first component into the ipsilateral posterior insular region, and the second component into ipsilateral posterior mesial temporo-occipital structures. Conclusions: SSS comprise an amalgam of two sequential, distinct cortical components, showing a very uniform and peculiar EEG pattern and cortical source solutions. As such, they must be clearly distinguished from interictal epileptiform discharges in patients with epilepsy. Significance: The awareness of these peculiar EEG characteristics may increase our ability to differentiate SSS from interictal epileptiform activity. The finding of a posterior insular source might serve as an inspiration for new physiological considerations regarding these enigmatic waveforms. © 2006 International Federation of Clinical Neurophysiology.

281. Zumsteg, D., D.M. Andrade, J.M. Del Campo, and R. Wennberg, Parietal lobe source localization and sensitivity to hyperventilation in a patient with subclinical rhythmic electrographic discharges of adults (SREDA). Clinical Neurophysiology, 2006. 117(10): p. 2257-2263.

Summary: Objective: Subclinical rhythmic electrographic discharges of adults (SREDA) is currently considered a benign EEG pattern of uncertain significance. The underlying cortical sources and generating mechanisms are unknown. We performed a source localization analysis of SREDA with the aim of better understanding this unusual EEG pattern. Methods: Multiple spontaneous episodes of typical SREDA were recorded in a patient during continuous EEG monitoring. Additional SREDA episodes were induced by hyperventilation. Source localization was carried out using statistical non-parametric mapping (SNPM) of low resolution electromagnetic tomography (LORETA). Results: SNPM of both time- and frequency-domain LORETA revealed a widespread biparietal cortical origin of SREDA, the anatomical distribution of which included the parietal operculum and the known vascular watershed areas between anterior, middle and posterior cerebral arteries. Vigorous deep hyperventilation induced SREDA on three of four attempts. Mean duration of the hyperventilation-induced SREDA was approximately three times longer than spontaneous events. Conclusions: Investigations in this patient with typical SREDA revealed hyperventilation sensitivity and a posterior hemispheric source localization maximal in the parietal cortex bilaterally, in large part overlying the anatomical distribution of the vascular watershed areas. Significance: The source localization results and sensitivity to hyperventilation suggest some sort of association between cerebral vascular supply and SREDA, as originally proposed by Naquet et al. [Naquet R, Louard C, Rhodes J, Vigouroux M. A propos de certaines décharges paroxystiques du carrefour temporo-pariéto-occipital. Leur activation par l'hypoxie. Rev Neurol 1961;105:203-207.]. © 2006 International Federation of Clinical Neurophysiology.

282. Zhang, Y., L. Ding, W. van Drongelen, K. Hecox, D.M. Frim, and B. He, A cortical potential imaging study from simultaneous extra- and intracranial electrical recordings by means of the finite element method. NeuroImage, 2006. 31(4): p. 1513-1524.

Summary: In the present study, we have validated the cortical potential imaging (CPI) technique for estimating cortical potentials from scalp EEG using simultaneously recorded electrocorticogram (ECoG) in the presence of strong local inhomogeneity, i.e., Silastic ECoG grid(s). The finite element method (FEM) was used to model the realistic postoperative head volume conductor, which includes the scalp, skull, cerebrospinal fluid (CSF) and brain, as well as the Silastic ECoG grid(s) implanted during the surgical evaluation in epilepsy patients, from the co-registered magnetic resonance (MR) and computer tomography (CT) images. A series of computer simulations were conducted to evaluate the present FEM-based CPI technique and to assess the effect of the Silastic ECoG grid on the scalp EEG forward solutions. The present simulation results show that the Silastic ECoG grid has substantial influence on the scalp potential forward solution due to the distortion of current pathways in the presence of the extremely low conductive materials. On the other hand, its influence on the estimated cortical potential distribution is much less than that on the scalp potential distribution. With appropriate numerical modeling and inverse estimation techniques, we have demonstrated the feasibility of estimating the cortical potentials from the scalp EEG with the implanted Silastic ECoG gird(s), in both computer simulations and in human experimentation. In an epilepsy patient undergoing surgical evaluation, the cortical potentials were reconstructed from the simultaneously recorded scalp EEG, in which main features of spatial patterns during interictal spike were preserved and over 0.75 correlation coefficient value was obtained between the recorded and estimated cortical potentials. The FEM-based CPI technique provides a means of connecting the simultaneous recorded ECoG and the scalp EEG and promises to become an effective tool to evaluate and validate CPI techniques using clinic data. © 2006 Elsevier Inc. All rights reserved.

283. Wolter, S., C. Friedel, K. Böhler, U. Hartmann, W.J. Kox, and M. Hensel, Presence of 14 Hz spindle oscillations in the human EEG during deep anesthesia. Clinical Neurophysiology, 2006. 117(1): p. 157-168.

Summary: Objective: To report on presence of human EEG spindle oscillations on the cortical level within flat periods of the burst-suppression pattern during propofol-induced anesthesia; to search for corresponding oscillations and possible functional connections. Methods: Artefact-free epochs of spindle activation were selected from the electroencephalograms of opiate-dependent patients undergoing rapid opiate detoxification. Power spectral analysis and source localization using low-resolution-brain-electromagnetic-tomography (LORETAKey) were performed. Results: Sinusoidal rhythms with waxing and waning amplitudes appeared after propofol-induced narcosis but no direct correlations could be determined between individual dosage and characteristic spindle attributes. The power maximum stood midline over the cortical areas, especially around Cz. We calculated a peak frequency of 14(±1.2) Hz. Motor fields, particularly in the frontal, parietal, and various cingulate areas, were found to be the primary sources of spindle oscillations in the cortex. Conclusions: The frequent occurrence of these localized spindle sources demonstrates the preference for motor fields. Spindle oscillations observed during propofol-induced narcosis were similar in frequency and shape to those observed in natural sleep. Significance: The results lend support to models that postulate a close link between the motor system and the organization of behavior. In addition, spindle rhythms under propofol bore some resemblance to spindle types which occur during sleep. © 2005 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

284. Waldorp, L.J., H.M. Huizenga, R.P.P.P. Grasman, K.B.E. Böcker, and P.C.M. Molenaar, Hypothesis testing in distributed source models for EEG and MEG data. Human Brain Mapping, 2006. 27(2): p. 114-128.

Summary: Hypothesis testing in distributed source models for the electro- or magnetoencephalogram is generally performed for each voxel separately. Derived from the analysis of functional magnetic resonance imaging data, such a statistical parametric map (SPM) ignores the spatial smoothing in hypothesis testing with distributed source models. For example, when intending to test a single voxel, actually an entire region of voxels is tested simultaneously. Because there are more parameters than observations, typically constraints are employed to arrive at a solution which spatially smooths the solution. If ignored, it can be concluded from the hypothesis test that there is activity at some location where there is none. In addition, an SPM on distributed source models gives the illusion of very high resolution. As an alternative, a multivariate approach is suggested in which a region of interest is tested that is spatially smooth. In simulations with MEG and EEG it is shown that clear hypothesis testing in distributed source models is possible, provided that there is high correspondence between what is intended to be tested and what is actually tested. The approach is also illustrated by an application to data from an experiment measuring visual evoked fields when presenting checker-board patterns. © 2005 Wiley-Liss, Inc.

285. Van Leeuwen, T., P. Been, C. Kuijpers, F. Zwarts, B. Maassen, and A. Van Der Leij, Mismatch response is absent in 2-month-old infants at risk for dyslexia. NeuroReport, 2006. 17(4): p. 351-355.

Summary: This study examined auditory processing in 2-month-old infants at genetic risk for dyslexia and in controls. Manipulated natural speech stimuli (/bAk/ and /dAk/), at either side of the phoneme boundary, were presented to these infants and their automatic cortical deviance responses were recorded. Control infants showed two distinct mismatch responses, thus extending similar findings reported with kindergartners in terms of topographical distribution and cortical sources. The absence of such mismatch responses in the infants at risk supports the hypothesis of basic auditory (temporal) processing impairments in the disorder. The results suggest that these early signs of deficient auditory processing may point to problematic categorical perception at a later age. © 2006 Lippincott Williams & Wilkins.

286. Tsai, A.C., M. Liou, T.P. Jung, J.A. Onton, P.E. Cheng, C.C. Huang, J.R. Duann, and S. Makeig, Mapping single-trial EEG records on the cortical surface through a spatiotemporal modality. NeuroImage, 2006. 32(1): p. 195-207.

Summary: Event-related potentials (ERPs) induced by visual perception and cognitive tasks have been extensively studied in neuropsychological experiments. ERP activities time-locked to stimulus presentation and task performance are often observed separately at individual scalp channels based on averaged time series across epochs and experimental subjects. An analysis using averaged EEG dynamics could discount information regarding interdependency between ongoing EEG and salient ERP features. Advanced tools such as independent component analysis (ICA) have been developed for decomposing collections of single-trial EEG records into separate features. Those features (or independent components) can then be mapped onto the cortical surface using source localization algorithms to visualize brain activation maps and to study between-subject consistency. In this study, we propose a statistical framework for estimating the time course of spatiotemporally independent EEG components simultaneously with their cortical distributions. Within this framework, we implemented Bayesian spatiotemporal analysis for imaging the sources of EEG features on the cortical surface. The framework allows researchers to include prior knowledge regarding spatial locations as well as spatiotemporal independence of different EEG sources. The use of the Electromagnetic Spatiotemporal ICA (EMSICA) method is illustrated by mapping event-related EEG dynamics induced by events in a visual two-back continuous performance task. The proposed method successfully identified several interesting components with plausible corresponding cortical activation topographies, including processes contributing to the late positive complex (LPC) located in central parietal, frontal midline, and anterior cingulate cortex, to atypical mu rhythms associated with the precentral gyrus, and to the central posterior alpha activity in the precuneus. © 2006 Elsevier Inc. All rights reserved.

287. Stern, J., D. Jeanmonod, and J. Sarnthein, Persistent EEG overactivation in the cortical pain matrix of neurogenic pain patients. NeuroImage, 2006. 31(2): p. 721-731.

Summary: Functional brain imaging of pain over the last years has provided insight into a distributed anatomical matrix involved in pain processing which includes multiple cortical areas. EEG/MEG-based imaging studies have mostly relied on settings of evoked nociception. We report here the spontaneous presence of enhanced activations in the pain matrix of the patient group on the basis of continuous EEG and functional Low Resolution Electromagnetic Tomography (LORETA) from 16 chronic neurogenic pain patients and 16 healthy controls. These overactivations occurred predominantly within the high theta (6-9 Hz) and low beta frequency ranges (12-16 Hz). Theta and beta overactivations were localized to multiple pain-associated areas, primarily to insular (IC), anterior cingulate (ACC), prefrontal, and inferior posterior parietal cortices, as well as to primary (S1), secondary (S2), and supplementary somatosensory (SSA) cortices. After a therapeutic lesion in the thalamus (central lateral thalamotomy, CLT), we followed a subgroup of 6 patients. Twelve months after surgery, activation in cingulate and insular cortices was significantly reduced. The presence of rhythmic processes in multiple, partially overlapping areas of the cortical pain matrix concur with the concept of thalamocortical dysrhythmia (TCD) that predicts increased thalamocortical low and high frequency oscillations ensuing from thalamic desactivation. These spontaneous, ongoing, frequency-specific overactivations may therefore serve as an anatomo-physiological hallmark of the processes underlying chronic neurogenic pain. © 2006 Elsevier Inc. All rights reserved.

288. Stein, M., T. Dierks, D. Brandeis, M. Wirth, W. Strik, and T. Koenig, Plasticity in the adult language system: A longitudinal electrophysiological study on second language learning. NeuroImage, 2006. 33(2): p. 774-783.

Summary: Event-related potentials (ERPs) were used to trace changes in brain activity related to progress in second language learning. Twelve English-speaking exchange students learning German in Switzerland were recruited. ERPs to visually presented single words from the subjects' native language (English), second language (German) and an unknown language (Romansh) were measured before (day 1) and after (day 2) 5 months of intense German language learning. When comparing ERPs to German words from day 1 and day 2, we found topographic differences between 396 and 540 ms. These differences could be interpreted as a latency shift indicating faster processing of German words on day 2. Source analysis indicated that the topographic differences were accounted for by shorter activation of left inferior frontal gyrus (IFG) on day 2. In ERPs to English words, we found Global Field Power differences between 472 and 644 ms. This may due to memory traces related to English words being less easily activated on day 2. Alternatively, it might reflect the fact that - with German words becoming familiar on day 2 - English words loose their oddball character and thus produce a weaker P300-like effect on day 2. In ERPs to Romansh words, no differences were observed. Our results reflect plasticity in the neuronal networks underlying second language acquisition. They indicate that with a higher level of second language proficiency, second language word processing is faster and requires shorter frontal activation. Thus, our results suggest that the reduced IFG activation found in previous fMRI studies might not reflect a generally lower activation but rather a shorter duration of activity. © 2006 Elsevier Inc. All rights reserved.

289. Stančák, A., J. Mlynář, H. Poláček, and J. Vrána, Source imaging of the cortical 10 Hz oscillations during cooling and warming in humans. NeuroImage, 2006. 33(2): p. 660-671.

Summary: Primary cold and warm afferent fibers show a robust overshoot in their firing during periods of temperature change, which subsides during tonic thermal stimulation. Our objective was to analyze cortical activation, on a scale of hundreds of milliseconds, occurring during the process of dynamic cooling and warming, based on an evaluation of the amplitude changes seen in 10 Hz electroencephalographic oscillations. Eleven right-handed subjects were exposed to innocuous cold ramp stimuli (from 32°C to 22°C, 10°C/s) and warm ramp stimuli (32°C to 42°C, 10°C/s) on the thenar region of their right palm, using a contact thermode. EEG was recorded from 111 scalp sites, and the 10 Hz current source densities were modeled using low-resolution electromagnetic tomography. During cooling, the earliest amplitude decreases of 10 Hz oscillations were seen in the contralateral posterior insula and secondary somatosensory cortex (SII), and the premotor cortex (PMC). During warming, the earliest events were only observed in the PMC and occurred ≈ 0.7 s later than during cooling. Linear regression analysis between 10 Hz current source densities and temperature variations revealed cooling-sensitive activation in the bilateral posterior insula, PMC and the anterior cingulate cortex. During warming, the amplitude of 10 Hz oscillations in the PMC and posterior insula correlated with stimulus temperature. Dynamic thermal stimulation activates, in addition to the posterior insula and parietal operculum, the lateral PMC. The activation of the anterior cingulate cortex during cooling may aid in the anticipation of the cold temperature end-point and provide continuous evaluation of the thermal stimulus. © 2006 Elsevier Inc. All rights reserved.

290. Sittiprapaporn, W., C. Chindaduangratn, and N. Kotchabhakdi, Pattern of language-related potential maps in cluster and noncluster initial consonants in consonant-vowel (CV) syllables. Songklanakarin Journal of Science and Technology, 2006. 28(5): p. 911-920.

Summary: Mismatch negativity (MMN) was used to investigate the processing of cluster and noncluster initial consonants in consonant-vowel syllables in the human brain. The MMN was elicited by either syllable with cluster or noncluster initial consonant, phonetic contrasts being identical in both syllables. Compared to the noncluster consonant, the cluster consonant elicited a more prominent MMN. The MMN to the cluster consonant occurred later than that of the noncluster consonant. The topography of the mismatch responses showed clear left-hemispheric laterality in both syllables. However, the syllable with an initial noncluster consonant stimulus produced MMN maximum over the middle temporal gyrus, whereas maximum of the MMN activated by the syllable with initial cluster consonant was observed over the superior temporal gyrus. We suggest that the MMN component in consonant-vowel syllables is more sensitive to cluster compared to noncluster initial consonants. Spatial and temporal features of the cluster consonant indicate delayed activation of left-lateralized perisylvian cell assemblies that function as cortical memory traces of cluster initial consonant in consonant-vowel syllables.

291. Séverac Cauquil, A., Y. Trotter, and M.J. Taylor, At what stage of neural processing do perspective depth cues make a difference? Experimental Brain Research, 2006. 170(4): p. 457-463.

Summary: The present study investigated the cortical processing of three-dimensional (3D) perspective cues in humans, to determine how the brain computes depth from a bidimensional retinal image. We recorded visual evoked potentials in 12 subjects in response to flat and in-perspective stimuli, which evoked biphasic potentials over posterior electrodes. The first, positive component (P1, at 90 ms) was not sensitive to perspective, while the second, negative peak (N1 at ∼150 ms) was significantly larger for 3D stimuli, regardless of attention. The amplitude increase due to perspective was seen on all posterior electrodes, but was largest over the right hemisphere, particularly at parietal sites. Source modeling low-resolution electromagnetic tomography (LORETA) confirmed that among the different areas participating in two- and three-dimensional stimuli processing, the right parietal source is the most enhanced by perspective depth cues. We conclude that the extraction of depth from perspective cues occurs at a second level of stimulus processing, by increasing the activity of the regions involved in 2D stimuli processing, particularly in the right hemisphere, possibly through feedback loops from higher cortical areas. These modulations would participate in the fine-tuned analysis of the 3D features of stimuli. © Springer-Verlag 2005.

292. Schicke, T., L. Muckli, A.L. Beer, M. Wibral, W. Singer, R. Goebel, F. Rösler, and B. Röder, Tight covariation of BOLD signal changes and slow ERPs in the parietal cortex in a parametric spatial imagery task with haptic acquisition. European Journal of Neuroscience, 2006. 23(7): p. 1910-1918.

Summary: The present study investigated the relation of brain activity patterns measured with functional magnetic resonance imaging (fMRI) and slow event-related potentials (ERPs) associated with a complex cognitive task. A second goal was to examine the neural correlates of spatial imagery of haptically - instead of visually - acquired representations. Using a mental image scanning task, spatial imagery requirements were systematically manipulated by parametrically varying the distance between haptically acquired landmarks. Results showed a close relation between slow ERPs and the blood oxygenation level dependent (BOLD) signal in human parietal lobe. Reaction times of mental scanning correlated with the distances between landmarks on the learned display. In parallel, duration and amplitude of slow ERPs and duration of the haemodynamic response systematically varied as a function of mental scanning distance. Source analysis confirmed that the ERP imagery effect likely originated from the same cortical substrate as the corresponding BOLD effect. This covariation of the BOLD signal with slow ERPs is in line with recent findings in animals demonstrating a tight link between local field potentials and the BOLD signal. The parietal location of the imagery effect is consistent with the idea that externally triggered (perceptual) and mentally driven (imagery) spatial processes are both mediated by the same supramodal brain areas. © The Authors (2006).

293. Saletu, B., P. Anderer, and G.M. Saletu-Zyhlarz, EEG topography and tomography (LORETA) in the classification and evaluation of the pharmacodynamics of psychotropic drugs. Clinical EEG and Neuroscience, 2006. 37(2): p. 66-80.

Summary: By multi-lead computer-assisted quantitative analyses of human scalp-recorded electroencephalogram (QEEG) in combination with certain statistical procedures (quantitative pharmaco-EEG) and mapping techniques (pharmaco-EEG mapping or topography), it is possible to classify psychotropic substances and objectively evaluate their bioavailability at the target organ, the human brain. Specifically, one may determine at an early stage of drug development whether a drug is effective on the central nervous system (CNS) compared with placebo, what its clinical efficacy will be like, at which dosage it acts, when it acts and the equipotent dosages of different galenic formulations. Pharmaco-EEG maps of neuroleptics, antidepressants, tranquilizers, hypnotics, psychostimulants and nootropics/cognition-enhancing drugs will be described. Methodological problems, as well as the relationships between acute and chronic drug effects, alterations in normal subjects and patients, CNS effects and therapeutic efficacy will be discussed. Imaging of drug effects on the regional brain electrical activity of healthy subjects by means of EEG tomography such as low-resolution electromagnetic tomography (LORETA) has been used for identifying brain areas predominantly involved in psychopharmacological action. This will be shown for the representative drugs of the four main psychopharmacological classes, such as 3 mg haloperidol for neuroleptics, 20 mg citalopram for antidepressants, 2 mg lorazepam for tranquilizers and 20 mg methylphenidate for psychostimulants. LORETA demonstrates that these psychopharmacological classes affect brain structures differently. By considering these differences between psychotropic drugs and placebo in normal subjects, as well as between mental disorder patients and normal controls, it may be possible to choose the optimum drug for a specific patient according to a key-lock principle, since the drug should normalize the deviant brain function. Thus, pharmaco-EEG topography and tomography are valuable methods in human neuropsychopharmacology, clinical psychiatry and neurology.

294. Rodríguez, V. and M. Valdés-Sosa, Sensory suppression during shifts of attention between surfaces in transparent motion. Brain Research, 2006. 1072(1): p. 110-118.

Summary: During transparent motion, attention to changes in the direction of one illusory surface will impede recognition of a similar event affecting the other surface if both are close together in time. This is a form of object-based attentional blink (AB). Here, we show that this AB is related to a smaller N200 response to the change in direction and that the response is even smaller for trials on which the subject makes mistakes compared to those with correct responses consistent with signal detection theory models. The variation of N200 associated with the AB can be modeled by an attenuation of current sources estimated in visual extrastriate cortex. These results suggest that the AB in the transparent motion paradigm is due to the suppression of sensory signals in early visual areas. © 2005 Elsevier B.V. All rights reserved.

295. Riera, J.J., P.A. Valdés, K. Tanabe, and R. Kawashima, A theoretical formulation of the electrophysiological inverse problem on the sphere. Physics in Medicine and Biology, 2006. 51(7): p. 1737-1758.

Summary: The construction of three-dimensional images of the primary current density (PCD) produced by neuronal activity is a problem of great current interest in the neuroimaging community, though being initially formulated in the 1970s. There exist even now enthusiastic debates about the authenticity of most of the inverse solutions proposed in the literature, in which low resolution electrical tomography (LORETA) is a focus of attention. However, in our opinion, the capabilities and limitations of the electro and magneto encephalographic techniques to determine PCD configurations have not been extensively explored from a theoretical framework, even for simple volume conductor models of the head. In this paper, the electrophysiological inverse problem for the spherical head model is cast in terms of reproducing kernel Hilbert spaces (RKHS) formalism, which allows us to identify the null spaces of the implicated linear integral operators and also to define their representers. The PCD are described in terms of a continuous basis for the RKHS, which explicitly separates the harmonic and non-harmonic components. The RKHS concept permits us to bring LORETA into the scope of the general smoothing splines theory. A particular way of calculating the general smoothing splines is illustrated, avoiding a brute force discretization prematurely. The Bayes information criterion is used to handle dissimilarities in the signal/noise ratios and physical dimensions of the measurement modalities, which could affect the estimation of the amount of smoothness required for that class of inverse solution to be well specified. In order to validate the proposed method, we have estimated the 3D spherical smoothing splines from two data sets: electric potentials obtained from a skull phantom and magnetic fields recorded from subjects performing an experiment of human faces recognition. © 2006 IOP Publishing Ltd.

296. Pun, T., T.I. Alecu, G. Chanel, J. Kronegg, and S. Voloshynovskiy, Brain-computer interaction research at the Computer Vision and Multimedia Laboratory, University of Geneva. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2006. 14(2): p. 210-213.

Summary: This paper describes the work being conducted in the domain of brain-computer interaction (BCI) at the Multimodal Interaction Group, Computer Vision and Multimedia Laboratory, University of Geneva, Geneva, Switzerland. The application focus of this work is on multimodal interaction rather than on rehabilitation, that is how to augment classical interaction by means of physiological measurements. Three main research topics are addressed. The first one concerns the more general problem of brain source activity recognition from EEGs. In contrast with classical deterministic approaches, we studied iterative robust stochastic based reconstruction procedures modeling source and noise statistics, to overcome known limitations of current techniques. We also developed procedures for optimal electroencephalogram (EEG) sensor system design in terms of placement and number of electrodes. The second topic is the study of BCI protocols and performance from an information-theoretic point of view. Various information rate measurements have been compared for assessing BCI abilities. The third research topic concerns the use of EEG and other physiological signals for assessing a user's emotional status. © 2006 IEEE.

297. Pourtois, G. and P. Vuilleumier, Chapter 4 Dynamics of emotional effects on spatial attention in the human visual cortex. Progress in Brain Research, 2006. 156: p. 67-91.

Summary: An efficient detection of threat is crucial for survival and requires an appropriate allocation of attentional resources toward the location of potential danger. Recent neuroimaging studies have begun to uncover the brain machinery underlying the reflexive prioritization of spatial attention to locations of threat-related stimuli. Here, we review functional brain imaging experiments using event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI) in a dot-probe paradigm with emotional face cues, in which we investigated the spatio-temporal dynamics of attentional orienting to a visual target when the latter is preceded by either a fearful or happy face, at the same (valid) location or at a different (invalid) location in visual periphery. ERP results indicate that fearful faces can bias spatial attention toward threat-related location, and enhance the amplitude of the early exogenous visual P1 activity generated within the extrastriate cortex in response to a target following a valid rather than invalid fearful face. Furthermore, this gain control mechanism in extrastriate cortex (at 130-150 ms) is preceded by an earlier modulation of activity in posterior parietal regions (at 40-80 ms) that may provide a critical source of top-down signals on visual cortex. Happy faces produced no modulation of ERPs in extrastriate and parietal cortex. fMRI data also show increased responses in the occipital visual cortex for valid relative to invalid targets following fearful faces, but in addition reveal significant decreases in intraparietal cortex and increases in orbitofrontal cortex when targets are preceded by an invalid fearful face, suggesting that negative emotional stimuli may not only draw but also hold spatial attention more strongly than neutral or positive stimuli. These data confirm that threat may act as a powerful exogenous cue and trigger reflexive shifts in spatial attention toward its location, through a rapid temporal sequence of neural events in parietal and temporo-occipital areas, with dissociable neural substrates for engagement benefits in attention affecting activity in extrastriate occipital areas and increased disengagement costs affecting intraparietal cortex. These brain-imaging results reveal how emotional signals related to threat can play an important role in modulating spatial attention to afford flexible perception and action. © 2006 Elsevier B.V. All rights reserved.

298. Pourtois, G., M. De Pretto, C.A. Hauert, and P. Vuilleumier, Time course of brain activity during change blindness and change awareness: Performance is predicted by neural events before change onset. Journal of Cognitive Neuroscience, 2006. 18(12): p. 2108-2129.

Summary: People often remain "blind" to visual changes occurring during a brief interruption of the display. The processing stages responsible for such failure remain unresolved. We used event-related potentials to determine the time course of brain activity during conscious change detection versus change blindness. Participants saw two successive visual displays, each with two faces, and reported whether one of the faces changed between the first and second displays. Relative to blindness, change detection was associated with a distinct pattern of neural activity at several successive processing stages, including an enhanced occipital P1 response and a sustained frontal activity (CNV-like potential) after the first display, before the change itself. The amplitude of the N170 and P3 responses after the second visual display were also modulated by awareness of the face change. Furthermore, a unique topography of event-related potential activity was observed during correct change and correct nochange reports, but not during blindness, with a recurrent time course in the stimulus sequence and simultaneous sources in the parietal and temporo-occipital cortex. These results indicate that awareness of visual changes may depend on the attentional state subserved by coordinated neural activity in a distributed network, before the onset of the change itself. © 2006 Massachusetts Institute of Technology.

299. Pogarell, O., C. Mulert, and U. Hegerl, Event related potentials and fMRI in neuropsychopharmacology. Clinical EEG and Neuroscience, 2006. 37(2): p. 99-107.

Summary: Event related potentials (ERP) are important clinical and research instruments in neuropsychiatry, particularly due to their strategic role for the investigation of brain function. These techniques are often underutilized in the evaluation of neurological and psychiatric disorders, but nevertheless they can be most useful and highly effective in the diagnostic workup of a wide range of neuropsychiatric disorders as well as in monitoring the course of the disorders and the prediction of treatment responses. ERP are noninvasive instruments that directly reflect cortical neuronal activity. Cortical neuronal dysfunction plays a major role in variable neuropsychiatric disorders, and a change in cortical activity under medication might reflect treatment response and could be useful for monitoring drug effects. ERP are the only methods with a sufficiently high time resolution for the analysis of the dynamic patterns of neuronal brain activity, e.g., synchronization and desynchronization, oscillations, coherence, gamma band activity, latency of event related activity, etc., which are crucial for a deeper understanding of functional (neurophysiological) correlates of cognitive, emotional and behavioral disturbances in neuropsychiatric patients. Methodological advances have further improved and strengthened the position of ERP concerning research and clinical application. The usefulness and applicability of ERP in determining and monitoring clinico-pharmacological effects will be summarized mainly by focussing on the auditory evoked P300 and the N1/P2 component of auditory evoked potentials. Owing to important recent developments in the field of brain functional diagnostics the combination of neurophysiological techniques and functional magnetic resonance imaging (fMRI) will be included.

300. Pizzagalli, D.A., L.A. Peccoralo, R.J. Davidson, and J.D. Cohen, Resting anterior cingulate activity and abnormal responses to errors in subjects with elevated depressive symptoms: A 128-channel study. Human Brain Mapping, 2006. 27(3): p. 185-201.

Summary: Depression has been associated with dysfunctional executive functions and abnormal activity within the anterior cingulate cortex (ACC), a region critically involved in action regulation. Prior research invites the possibility that executive deficits in depression may arise from abnormal responses to negative feedback or errors, but the underlying neural substrates remain unknown. We hypothesized that abnormal reactions to error would be associated with dysfunctional rostral ACC activity, a region previously implicated in error detection and evaluation of the emotional significance of events. To test this hypothesis, subjects with low and high Beck Depression Inventory (BDI) scores performed an Eriksen Flanker task. To assess whether tonic activity within the rostral ACC predicted post-error adjustments, 128-channel resting EEG data were collected before the task and analyzed with low-resolution electromagnetic tomography (LORETA) using a region-of-interest approach. High BDI subjects were uniquely characterized by significantly lower accuracy after incorrect than correct trials. Mirroring the behavioral findings, high BDI subjects had significantly reduced pretask gamma (36.5-44 Hz) current density within the affective (rostral; BA24, BA25, BA32) but not cognitive (dorsal; BA24′, BA32′) ACC subdivision. For low, but not high, BDI subjects pretask gamma within the affective ACC subdivision predicted post-error adjustments even after controlling for activity within the cognitive ACC subdivision. Abnormal responses to errors may thus arise due to lower activity within regions subserving affective and/or motivational responses to salient cues. Because rostral ACC regions have been implicated in treatment response in depression, our findings provide initial insight into putative mechanisms fostering treatment response. © 2005 Wiley-Liss, Inc.

301. Pascual-Montano, A., J.M. Carazo, K. Kochi, D. Lehmann, and R.D. Pascual-Marqui, Nonsmooth nonnegative matrix factorization (nsNMF). IEEE Transactions on Pattern Analysis and Machine Intelligence, 2006. 28(3): p. 403-415.

Summary: We propose a novel nonnegative matrix factorization model that aims at finding localized, part-based, representations of nonnegative multivariate data items. Unlike the classical nonnegative matrix factorization (NMF) technique, this new model, denoted "nonsmooth nonnegative matrix factorization" (nsNMF), corresponds to the optimization of an unambiguous cost function designed to explicitly represent sparseness, in the form of nonsmoothness, which is controlled by a single parameter. In general, this method produces a set of basis and encoding vectors that are not only capable of representing the original data, but they also extract highly localized patterns, which generally lend themselves to improved interpretability. The properties of this new method are illustrated with several data sets. Comparisons to previously published methods show that the new nsNMF method has some advantages in keeping faithfulness to the data in the achieving a high degree of sparseness for both the estimated basis and the encoding vectors and in better interpretability of the factors. © 2006 IEEE.

302. Ogawa, K., H. Nittono, and T. Hori, Cortical regions activated after rapid eye movements during REM sleep. Sleep and Biological Rhythms, 2006. 4(1): p. 63-71.

Summary: The present study investigated the cortical regions activated during rapid eye movement (REM) sleep by identifying the sources of electric currents of brain potentials related to rapid eye movements using low-resolution brain electromagnetic tomography (LORETA). The brain potentials measured were the lambda response (P1 and P2) during wakefulness and the lambda-like response (P1r and P2r) during REM sleep. Fifteen healthy university students participated in this study. During wakefulness, the sources of the electric current of the lambda response (P1 and P2) were estimated to be in the primary and secondary visual cortices (BA 17, 18). During REM sleep, the P1r has a source in a higher order visual area (precuneus; BA 7, 31) and P2r comes from the primary and secondary visual cortices (BA 17, 18). In addition, the density of electric current in the premotor and fronto-central regions including anterior cingulate gyrus was higher after rapid eye movements, which was a discriminative feature of REM sleep. The results of this study suggest that these activities that occur after rapid eye movements might underlie the generation of vivid visual images of dreaming. © 2006 The Author Journal compilation © 2006 Japanese Society of Sleep Research.

303. Neuhaus, A., M. Bajbouj, T. Kienast, P. Kalus, D. Von Haebler, G. Winterer, and J. Gallinat, Persistent dysfunctional frontal lobe activation in former smokers. Psychopharmacology, 2006. 186(2): p. 191-200.

Summary: Objective: Chronic smoking and nicotine exposure are accompanied by impaired cognitive task performance, modulated cerebral activity in brain imaging studies, and neuritic damage in experimental animals. The profile of the described dysfunctions matches frontal lobe circuits which also play a role in reward processing and reinforcement behavior. However, it is largely unknown if cerebral dysfunctions are reversible or persist during long term abstinence. Materials and methods: Cortical activation during auditory target processing (oddball task, P300 component) was recorded with 32-channel EEG in 247 healthy subjects consisting of 84 smokers, 53 former smokers (mean time of abstinence 11.9 years), and 110 never smokers. Results: Both current smokers and former smokers exhibited significantly diminished P300 amplitudes (Cz, Pz) relative to never smokers. Neuroelectric source analysis (low resolution brain electromagnetic tomography) revealed a hypoactivation of the anterior cingulate, orbitofrontal, and prefrontal cortex in smokers compared to never smokers. A similar profile of hypoactivation was observed in former smokers. Conclusion: For the first time, evidence is provided that dysfunctional activation of frontal lobe networks in smokers is also present in long term abstainers. © Springer-Verlag 2006.

304. Nakamura, W., S. Koyama, S. Kuriki, and Y. Inouye, Smoothness constraint for the estimation of current distribution from EEG/MEG data. ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, 2006. 2.

Summary: Separation of EEG (Electroencephalography) or MEG (Magnetoencephalography) data into activations of small dipoles or current density distribution is an ill-posed problem in which the number of parameters to estimate is larger than the dimension of the data. Several constraints have been proposed and used to avoid this problem, such as minimization of the L1-norm of the current distribution or minimization of Laplacian of the distribution. In this paper, we propose another biologically plausible constraint, sparseness of spatial difference of the current distribution. By numerical experiments, we show that the proposed method estimates current distribution well from both data generated by strongly localized current distributions and data generated by currents broadly distributed. © 2006 IEEE.

305. Nakamura, W., S. Koyama, S. Kuriki, and Y. Inouye, Estimation of current density distributions from EEG/MEG data by maximizing sparseness of spatial difference. Proceedings - IEEE International Symposium on Circuits and Systems, 2006: p. 1071-1074.

Summary: Separation of EEG(Electroencephalography) or MEG(Magnetoencephalography) data into activations of small dipoles or current density distribution is an ill-posed problem in which the number of parameters to estimate is larger than the dimension of the data. Several constraints have been proposed and used to avoid this problem, such as minimization of the Linorm of the current distribution or minimization of Laplacian of the distribution. In this paper, we propose another constraint that the current density distribution changes at only a small number of areas and these changes can be large. By numerical experiments, we show that the proposed method estimates current distribution well from both data generated by strongly localized current distributions and data generated by currents broadly distributed. © 2006 IEEE.

306. Mulert, C., G. Juckel, I. Giegling, O. Pogarell, G. Leicht, S. Karch, P. Mavrogiorgou, H.J. Möller, U. Hegerl, and D. Rujescu, A Ser9Gly polymorphism in the dopamine D3 receptor gene (DRD3) and event-related P300 potentials. Neuropsychopharmacology, 2006. 31(6): p. 1335-1344.

Summary: An important reason for the interest in P300 event-related potentials are findings in patients with psychiatric disorders like schizophrenia or alcoholism in which attenuations of the P300 amplitude are common findings. The P300 wave has been suggested to be a promising endophenotype for genetic research since attenuations of the amplitude and latency can be observed not only in patients but also in relatives. In parallel, the search for genes involved in the pathogenesis of psychiatric disorders has revealed for both, schizophrenia and alcoholism an association with a DRD3 Ser9Gly polymorphism in a number of studies. In the present study, we have investigated 124 unrelated healthy subjects of German descent and have found diminished parietal and increased frontal P300 amplitudes in Gly9 homozygotes in comparison to Ser9 carriers. This finding suggests a possible role of the DRD3 receptor gene in the interindividual variation of P300 amplitudes. Further studies should address the direct role of the DRD3 Ser9Gly polymorphism in attenuated P300 amplitudes in psychiatric disorders like schizophrenia or alcoholism. © 2006 Nature Publishing Group All rights reserved.

307. Meyer, M., S. Baumann, and L. Jancke, Electrical