P3b ERP

Neural co-activation in frontal and central cortex was examined during a visual oddball task using wavelet coherence. EEG was recorded during a visual oddball task, presented to 12 participants with a random mix of 15% oddball targets and 85% frequent non-target letters over 265 trials. Wavelet coherence of individual trials was shown to distinguish frequent and oddball trials. Averaged wavelet coherence showed significant differences: oddball targets showed higher delta-theta activity whereas frequent background stimuli showed higher gamma activity. Increased gamma coherence appeared to be related to expectation of the targets with our analysis showing an R 2 of 0.935 for the relationship between averaged sections of gamma coherence and the number of intervening (frequent) trials since the last oddball.

Higher mental functions depend on global cerebral functional coordination. Our aim was to study fast modulation of functional networks in schizophrenia that has not been previously assessed. Graph-theory was used to analyze the electroencephalographic (EEG) activity during an odd-ball task in 57 schizophrenia patients (18 first episode patients, FEPs) and 59 healthy controls. Clustering coefficient (CLC), characteristic path length (PL) and small-worldness (SW) were computed at baseline ([-300 0] ms prior to stimulus delivery) and response ([150 450] ms post-stimulus) windows. Clinical and cognitive assessments were performed. CLC, PL and SW showed a significant modulation between baseline and response in controls but not in patients. Patients obtained higher CLC and SW at baseline, lower CLC and higher PL at response, and diminished modulation of CLC and SW as compared to controls. In patients, CLC and SW modulation were inversely associated to cognitive performance in executive ta...

The present study aimed to elucidate the neuro-cognitive processes underlying age-related differences in working memory. Young and middle-aged participants performed a two-choice task with low and a 2-back task with high working memory load. The P300, an event-related potential reflecting controlled stimulus-response processing in working memory, and the underlying neuronal sources of expected age-related differences were analyzed using sLORETA. Response speed was generally slower for the middle-aged than the young group. Under low working memory load the middle-aged participants traded speed for accuracy. The middle-aged were less efficient in the 2-back task as they responded slower while the error rates did not differ for groups. An age-related decline of the P300 amplitude and characteristic topographical differences were especially evident in the 2-back task. A more detailed analysis of the P300 in non-target trials revealed that amplitudes in the young but not middle-aged group differentiate between correctly detected vs. missed targets in the following trial. For these trials, source analysis revealed higher activation for the young vs. middle-aged group in brain areas which support working memory processes. The relationship between P300 and overt performance was validated by significant correlations. To sum up, under high working memory load the young group showed an increased neuronal activity before a successful detected target, while the middle-aged group showed the same neuronal pattern regardless of whether a subsequent target will be detected or missed. This stable memory trace before detected targets was reflected by a specific activation enhancement in brain areas which orchestrate maintenance, update, storage, and retrieval of information in working memory.

Objectives: Gamma (`40 Hz') rhythms may play a role in the integration of sensory processing activity. Impaired temporal integration may be a key feature of the associated disturbances in schizophrenia. This is the ®rst study to examine the time course of Gamma activity induced in response to stimuli in this disorder. Methods: Gamma activity induced in response to task-relevant and irrelevant auditory oddball stimuli was examined in 35 medicated schizophrenics and 35 age-and gender-matched normal controls. We employed a moving Welch window with short time FFT to examine the time course of Gamma amplitude. The amplitude spectrum for each time point was de-trended to eliminate any contribution of broad spectrum activity (EEG or EMG) to Gamma amplitude. Results: For targets, schizophrenics showed a signi®cant decrease in post-stimulus Gamma response amplitude in left hemisphere and frontal sites and an increase in right hemisphere and parieto-occipital sites (P , 0:0009). The abnormalities correlated with PANSS general symptom scores. In the non-targets (at a different latency), schizophrenics showed a widespread Gamma decrease (P , 0:0005). Conclusions: The Gamma ®ndings in non-targets may re¯ect an abnormality in appropriately processing irrelevant stimuli. This could result in defective processing of the context (integration) of relevant target information.

The study of the mechanisms involved in cognition is of paramount importance for the understanding of the neurobiological substrates in psychiatric disorders. Hence, this research is aimed at exploring the brain network dynamics during a cognitive task. Specifically, we analyze the predictive capability of the pre-stimulus theta activity to ascertain the functional brain dynamics during cognition in both healthy and schizophrenia subjects. Firstly, EEG recordings were acquired during a three-tone oddball task from fifty-one healthy subjects and thirty-five schizophrenia patients. Secondly, phase-based coupling measures were used to generate the time-varying functional network for each subject. Finally, pre-stimulus network connections were iteratively modified according to different models of network reorganization. This adjustment was applied by minimizing the prediction error through recurrent iterations, following the predictive coding approach. Both controls and schizophrenia pa...

Background: Uremia is associated with impairment of different cognitive functions. However the pathogenesis of this cognitive dysfunction is unknown. Objective: In this study, long-latency event-related potentials (ERPs) were used to assess changes in cortical function due to hemodialysis treatment. Methods: In this cross-sectional study, we measured event-related potentials in 15 end-stage renal disease (ESRD) patients maintained on hemodialysis, two hours before and two hours after they underwent hemodialysis and compared their data with a strictly age and sex matched healthy control group. The P3 was elicited by using standard auditory ''odd-ball'' paradigm and the data obtained was statistically analyzed (Wilcoxon signed ranks, Mann Whitney). Results: Before hemodialysis, the patients' P3 latency (47.73 ± 39.47 ms) was significantly increased as compared with that of healthy control group (308.4 ± 13.73 ms) (p = 0.001). After hemodialysis, P3 latency of the patients showed a significant decrease (347.73 ± 39.47-325.20 ± 37.15 ms, p = 0.001). P3 latency after dialysis was not significantly different from controls. No significant correlation was noted between various biochemical parameters (hemoglobin, blood urea, creatinine, uric acid and calcium) and P3 latency or amplitude. Conclusions: Removal of uremic toxins by hemodialysis leads to an improvement in cognitive processing.

Although cognitive functioning in schizophrenia continues to be the focus of considerable research, few studies have attempted to evaluate the cognitive functions of neuroleptic treatment-resistant schizophrenic patients. Reduced amplitude of the P300 event-related potential (ERP) is one of the most consistently reported cognitive abnormality in schizophrenia. We therefore sought to determine whether treatment-resistant schizophrenic patients are also characterized by a significant reduction in P300 amplitude. Subjects responded to an infrequent visual stimulus while ignoring binaurally presented auditory stimuli. No group differences were observed for reaction time or P300 amplitude. The percentage of correct responses was excellent for all subjects, although controls were more accurate.

Deficits in processing contextual information are one of the main features of cognitive dysfunction in schizophrenia, but the neurophysiologic substrate underlying this dysfunction is poorly understood. We used ERPs to investigate local contextual processing in schizophrenic patients. Local context was defined as the occurrence of a short predictive series of stimuli occurring before delivery of a target event. Response times of predicted targets were faster in controls compared to patients. Schizophrenia patients failed to generate the P3b latency shift between predicted and random targets that was observed in controls and demonstrated a prominent reduction of the peak of an early latency context dependent positivity. The current study provides evidence of contextual processing deficits in schizophrenia patients by demonstrating alteration in the behavioral and neural correlates of local contextual processing.

There is a debate on whether delusional misidentification syndromes (DMSs) and schizophrenia are distinct disorders. Informationprocessing deficits have been found in both. Since the P300 component of event-related potentials (ERPs) reflects attention and working memory (WM) mechanisms, the P300 elicited during a WM test was studied in schizophrenic patients with DMS in comparison to schizophrenic patients without DMS and controls. Nine schizophrenic patients with DMS, 11 without DMS and 11 healthy controls were tested with a computerized version of the digit span test of the Wechsler batteries. Auditory ERPs were measured during the anticipatory period of the test. P300 amplitude in prefrontal areas was found to be significantly reduced in schizophrenics without DMS and markedly less in DMS patients compared to controls. P300 latency in the central midline brain region was significantly prolonged in DMS patients compared to the other groups. Memory performance was significantly reduced in both patient groups as compared to healthy controls. The results may indicate abnormalities in both allocation of attentional resources and automatic orienting in schizophrenic patients with DSM. In contrast, even though schizophrenic patients without DMS exhibit partial similarities with patients suffering from DMS, they show excessive reduction of P300 amplitude located at the left frontal area. Future studies might clarify these issues.

Background: Electroencephalographic (EEG) coherence analysis is a noninvasive technique for studying corticocortical associations. As there is evidence for a dysfunction of the prefrontal dorsolateral cortex in schizophrenia, we hypothesized to find lower frontal EEG coherence in schizophrenia. Methods: EEG amplitude and coherence analysis was performed in 16 antipsychotic-free schizophrenic patients and 16 healthy controls. EEG recordings were done with 19 gold-plated electrodes placed according to the International 10/20 system against averaged signals from both earlobes. Local coherence was computed for 22 adjacent electrode pairs within the hemispheres and interhemispheric coherence for eight corresponding electrode pairs of both hemispheres in the delta, theta, alpha, and beta-1 band. Results: Amplitude and interhemispheric coherence analysis revealed no differences. Local EEG coherence was significantly lower in schizophrenic patients for Fp1-F7 in the delta (p ϭ .001) and the theta band (p ϭ .002), and at F7-F3 in the alpha band (p ϭ .002). In the delta band coherence of Fp1-F7 was inversely correlated to the Positive and Negative Syndrome Scale positive symptoms subscore (R ϭ Ϫ.74, p ϭ .014). Conclusions: Assuming that EEG coherence can be used to index functional coupling between brain areas under the electrodes, the low EEG coherence in Fp1-F7 and F7-F3 in schizophrenic patients might reflect impaired information processing in the left dorsolateral prefrontal cortex.

Objective: Patients suffering from posttraumatic stress disorder (PTSD) exhibit hyper arousal symptoms and attention problems which were frequently investigated using the P3 event-related potentials (ERPs). Our study aimed at providing more precise knowledge of the functional significance of the P3 alteration seen in PTSD by revealing its spatio-temporal dynamics.
Methods: Fifteen PTSD patients and fifteen healthy trauma-exposed controls participated in a three-tone ‘‘oddball” task while their brain activity was recorded by magnetoencephalography (MEG). They were
asked to detect rare target tones and ignore standard tones and infrequent threatening distractors. An adaptive spatial-filter method (SAM beamformer) was applied for source estimation.
Results: Compared with controls, PTSD patients had more incorrect responses to standard stimuli. On the brain level, PTSD patients showed hyperactivity in the dorsolateral prefrontal cortex and anterior cingulate
cortex in response to standard sounds, decreased activity in those regions in response to threatening distractors, and decreased orbitofrontal activity in response to target stimuli.
Conclusions: Increased frontal activation in response to standard, neutral, stimuli may reflect greater resource allocation dedicated to cognitive control mechanisms during routine functioning in PTSD.
Decreased frontal activation in response to rare stimuli may reflect subsequently reduced residual resources for detecting rare stimuli and for emotion regulation. This may explain the hypervigilance and attention problems commonly reported by patients.
Significance: The current findings contribute to a better understanding of the mechanisms underlying the attention deficiency in PTSD, and highlight altered activity in specific frontal regions as potential biomarkers.

Perjanjian ini berlaku terhadap orang dan badan yang menjadi penduduk salah satu atau kedua Negara Pihak pada Perjanjian. PAJAK-PAJAK YANG DICAKUP DALAM PERJANJIAN (1) Perjanjian ini diterapkan terhadap pajak-pajak yang berlaku sekarang ini, yaitu : (a) Dalam hal Indonesia, pajak penghasilan yang dikenakan berdasarkan Undang-Undang Pajak Penghasilan Tahun 1984, Pajak Perseroan Tahun 1925, dan Pajak atas Bunga, Dividen, dan Royalti Tahun 1970. (b)

Neurophysiological deficits in the left dorsolateral prefrontal cortex (DLPFC) have been described in positron emission tomography studies of schizophrenia and depression. In schizophrenia and depression this deficit has been associated with the syndromes of psychomotor poverty and psychomotor retardation, respectively. Such findings lead to a prediction that DLPFC dysfunction is symptom rather than disease related. This prediction was empirically tested in a retrospective study that pooled data from 40 patients meeting research diagnostic criteria for depression and 30 patients meeting DSM-III R criteria for schizophrenia. The patients were categorised into those with and without poverty of speech, a symptom that is an observable manifestation of psychomotor impairment. The profile of regional cerebral blood flow (rCBF), measured in all subjects under resting conditions, was subsequently compared in these two groups. Patients with poverty of speech had significantly lower rCBF in the left DLFPC. This reduction of rCBF was independent of diagnosis. The findings support the view that the study of symptoms, or symptom clusters, can provide information additional to that of traditional diagnostic systems in the study of the major psychoses. (7 Neurol Neurosurg Psychiatry 1993;56: 1290-1294 Studies of cerebral neurophysiology, using functional imaging techniques, indicate multifocal regional abnormalities in both schizophrenia and depression. The presence of multifocal deficits in both disorders is consistent with current conceptualisations of an anatomically distributed neural basis to higher cerebral functions." 2 Among the range of functional deficits reported in schizophrenia and depression, the most robust finding has been that of 'hypofrontality'.4 Recent studies, particularly those using more refined data analytic techniques, have provided greater anatomical specificity to this finding with the demonstration of dysfunction in the left dorsolateral prefrontal cortex (DLPFC) in both schizophrenia and depression.5 6

Objective: Somatic hypervigilance describes a clinical presentation in which people report more, and more intense, bodily sensations than is usual. Most explanations of somatic hypervigilance implicate altered information processing, but strong empirical data are lacking. Attention and working memory are critical for information processing, and we aimed to evaluate brain activity during attention/working memory tasks in people with and without somatic hypervigilance. Method: Data from 173 people with somatic hypervigilance and 173 controls matched for age, gender, handedness, and years of education were analyzed. Event-related potential (ERP) data, extracted from the continuous electroencephalograph recordings obtained during performance of the Auditory Oddball task, and the Two In A Row (TIAR) task, for N1, P2, N2, and P3, were used in the analysis. Betweengroup differences for P3 amplitude and N2 amplitude and latency were assessed with two-tailed independent t tests. Between-group differences for N1 and P2 amplitude and latency were assessed using mixed, repeated measures analyses of variance (ANOVAs) with group and Group × Site factors. Linear regression analysis investigated the relationship between anxiety and depression and any outcomes of significance. Results: People with somatic hypervigilance showed smaller P3 amplitudes-Auditory Oddball task: t(285) = 2.32, 95% confidence interval, CI [3.48, 4.47], p = .026, d = 0.27; Two-In-A-Row (TIAR) task: t(334) = 2.23, 95% CI [2.20; 3.95], p = .021, d = 0.24-than case-matched controls. N2 amplitude was also smaller in people with somatic hypervigilance-TIAR task: t (318) = 2.58, 95% CI [0.33, 2.47], p = .010, d = 0.29-than in case-matched controls. Neither depression nor anxiety was significantly associated with any outcome. Conclusion: People with somatic hypervigilance demonstrated an event-related potential response to attention/working memory tasks that is consistent with altered information processing.

SChizophrenia Is characterised by severe abnormalities of affect, behaviour and cognition Including deficits In working memory and atlention. A previous PET study from this group reported on the functional neuroanatomy of work• ing memory and attention In 10 normal human subjects using a simple batlery of visual atlention and memory tasks. The present study reports on the func• tional neuroanatomy of 10 subjects with schizophrenia (age range 22~7 years) who performed those same tasks. The subjects performed the tasks while In the PET camera (Siemens-eT1 951R scanner, 3D mode, infused oxygen-15 water as blood-flow tracer). Event-related potentials (ERP) were recorded simultaneously. The cognitive tasks examined aspects of visual worklng memory and atlention, including switching attention and reloading worklng memory, as well as a sensorimotor control task. All subjects received prior training In each task. Statistical parametric mapping (SPM) method• ology was used to analyse the data after the Images were stereotactically normalised and smoothed. Foci of statistically significant relative regional cerebral blood flow (rCBF) change were then Identified. Our previous study of normal subjects showed multiple regions in the prefrontal cortex that were activated when performing the same tasks. The present results, however, Indicate that schizophrenic patients may activate a less extensive network of C<Hlctivated fields. These results support the hypothesis that there Is abnormal prefrontal cortical function in patients with schizophrenia.

Gamma oscillations are essential for functional neural assembly formation underlying higher cerebral functions. Previous studies concerning gamma band power in schizophrenia have yielded diverse results.
In this study, we assessed gamma band power in minimally treated patients with schizophrenia, their first-degree relatives and healthy controls during an odd-ball paradigm performance; in addition to the relation between gamma power and cognitive performance.
We found a higher gamma power in the patients group when compared to healthy controls at P3, P4, Fz, Pz and T5 sites. Compared to relatives, gamma power in patients was only marginally higher over P3 and P4. We found a nearly significant inverse association between gamma power at F4 and Tower of London performance in the patients, as well as a significant inverse association between gamma power at T5 and verbal memory and working memory scores in the relatives.
These results support higher total gamma power in association to schizophrenia and its inverse association to cognitive performance in patients and their first-degree relatives.

In schizophrenia there seems to be an inefficient activation of prefrontal and hippocampal regions. Patients tend to show worse cognitive performance in functions subserved by those regions as compared to healthy controls in spite of higher regional activation. However, the association between activation abnormalities and cognitive deficits remains without being understood. In the present study, we compared cerebral perfusion using single photon emission tomography (SPECT) in patients and controls to study the association between activation patterns and cognitive performance in this disease. The SPECT studies were simultaneously obtained with an electrophysiological recording during a P300 paradigm to elicit P3a and P3b components. We included 23 stable patients with paranoid schizophrenia and 29 healthy controls that underwent clinical and cognitive assessments. Patients with schizophrenia showed an increased perfusion in the right hippocampus with respect to healthy controls, they also displayed a statistically significant inverse association between perfusion in the left hippocampus and verbal memory performance. Healthy controls showed an inverse association between perfusion in the left dorsolateral prefrontal (DLPF) region and working memory performance. P3b but not P3a amplitude was significantly lower in patients. The limbic overactivation in the patients may contribute to their cognitive deficits in verbal memory.

The " dysconnection hypothesis " of psychosis suggests that a disruption of functional integration underlies cognitive deficits and clinical symptoms. Impairments in the P300 potential are well documented in psychosis. Intrinsic (self-)connectivity in a frontoparietal cortical hierarchy during a P300 experiment was investigated. Dynamic Causal Modeling was used to estimate how evoked activity results from the dynamics of coupled neural populations and how neural coupling changes with the experimental factors. Twenty-four patients with psychotic disorder, twenty-four unaffected relatives, and twenty-five controls underwent EEG recordings during an auditory oddball paradigm. Sixteen frontoparietal network models (including primary auditory, superior parietal, and superior frontal sources) were analyzed and an optimal model of neural coupling, explaining diagnosis and genetic risk effects, as well as their interactions with task condition were identified. The winning model included changes in connectivi-ty at all three hierarchical levels. Patients showed decreased self-inhibition—that is, increased cortical

Objective: Previous studies using event-related potentials (ERPs) in post-traumatic stress disorder (PTSD) have demonstrated reduced P3 amplitude during target detection and working memory (WM) processes. This study investigated effects of psychotropic medication (primarily antidepressants) on these ERP components. Methods: ERPs were recorded from 26 scalp sites in 34 PTSD patients (20 unmedicated, 14 medicated) with age-and gender-matched controls during a WM paradigm that involved detection of target letters on a visual display. Results: As expected, PTSD patients showed a reduced amplitude P3wm component during WM updating and a reduced and delayed target P3 component. Contrary to expectation, these ERP effects were most apparent in the medicated subgroup of PTSD patients. The medicated PTSD subgroup showed a trend towards reduced P3wm amplitude compared with controls and a significant amplitude reduction and delay of target P3 component, while there was little difference between the non-medicated PTSD subgroup and controls. Neither ERP nor behavioural measures were related to Clinician Administered PTSD Scale (CAPS) symptom severity measures. Conclusions: These results are consistent with research that suggests antidepressant medication may impair working memory performance. Significance: The present study illustrates the importance of monitoring medication effects on cognitive performance during clinical efficacy studies.

Quantitative descriptors of resting electroencephalogram (EEG) (QEEG) and event-related potentials (QERP) to visual and auditory stimuli were obtained from normal subjects and 94 chronic schizophrenic patients on medication, 25 chronic schizophrenics off medication, and 15 schizophrenics with no history of medication. These schizophrenic groups showed a high incidence of neurometric features that were significantly deviant from normative values. Multivariate discriminant analysis using these features successfully separated the schizophrenic patients from normals with high accuracy in independent replication. The data from the medicated group were subjected to cluster analysis. Newly developed algorithms were used for objective selection of the most effective set of variables for clustering and the optimum number of clusters to be sought. Five clusters were obtained, containing roughly equivalent proportions of the sample with markedly different QEEG profiles. The whole sample was then classified into these clusters. Each cluster contained patients both on and off medication, but patients who had never been medicated were classified into only three of these clusters. No significant clinical or demographic differences were found betweeen members of the five clusters; however, clear differences in QERP profiles were seen. These results are described in detail and possible physiological and pharmacological implications are discussed.

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Objective: We investigated differences between children and adults in selective attention. Methods: Event-related potentials of 9 year-old children and adults were studied. Subjects performed an active dichotic novelty oddball task. We examined age-related differences in early selection by comparing non-target tones and late selection by comparing target tones in the attended and unattended channels.

This study investigated the time-frequency dynamics of P300 generation in patients with first-onset schizophrenia. A group of 40 patients with first-onset schizophrenia and 40 controls performed an auditory oddball task. Wavelet analysis of the single-trial data was used to compute the Event-Related Spectral Perturbation (ERSP) and the Inter-Trial Phase Coherence (ITC) for the delta, theta, alpha, beta and gamma bands on the 50 ms window around peak P300 amplitude. The contribution of power and synchrony for P300 amplitudes was studied through correlation and regression analysis. Further, two sub-samples in which patients had lower or higher P300 amplitudes than their control match were contrasted. P300 amplitude did not differ between patients and controls. The frequency domain analysis revealed that controls display larger reductions on gamma power than patients. However, this gamma activity might be the result of micro-saccadic muscular artifacts. Regression analysis shows that P300 amplitude is highly dependent on delta power and synchronization. The analysis of the subsamples confirmed that while gamma power differences are dependent on the diagnosis, delta and theta synchronization are related to P300 amplitude, irrespective of diagnosis.

The phase-synchronization of Gamma-band oscillations has been postulated as a mechanism of "network binding" and implicated in various aspects of perception, memory, and cognition. The current study investigates a possible link between Gamma synchrony and individual differences in intelligence within the theory of fluid and crystallized intelligence, with due reference to Hebbian theory. The hypothesis is that there are significant correlations between cognitive performance and synchronous Gamma activity across diverse brain regions. EEG data were recorded from 35 healthy participants, and the peak magnitude and latency of early and late Gamma Synchrony were extracted using a method for quantifying phase synchronization across multiple sites. Participants also completed 11 diverse cognitive ability tests tapping fluid and crystallized intelligence. Overall, moderate-sized correlations were obtained between accuracy and speed composite scores, derived from the ability tests, and magnitude and latency indices of Gamma synchrony. Phase-synchronous Gamma activity provides a plausible physiological mechanism that might account for individual differences in cognitive abilities.

Objective ± Various degenerative cerebral diseases and even depression may cause abnormalities of the cognitive event related potentials (ERPs). We conducted the present study to elucidate the effects of ischemic stroke on the P300 ERP component. Material and methods ± We recorded the P300 wave using an auditory oddball paradigm in 38 consecutive brain infarct patients with mild neurological de®cits at 3 and 12 months poststroke, and in 29 healthy control subjects. Results ± Brain infarction slightly prolonged the P300 latency, and the observed delay was related to the presence and degree of post-stroke depression evaluated with the Zung Depression Scale and the DSM-III criteria. Infarction did not affect the P300 amplitude or its distribution on the scalp. The results of the patients with hemispheric brain infarction and those of the patients with brainstem infarction were similar, and also the values of the patients with the left-and right-sided lesions. The normal physiological correlation between subject age and the P300 latency was absent at 3 months post-stroke, but was present at 12 months post-stroke. Conclusion ± Brain infarction delays the P300 ERP and temporarily distorts its age-related physiology. The increase of the P300 latency seems to be associated with the post-stroke depression.

Central auditory processing in schizophrenia patients with a history of auditory hallucinations has been reported to be impaired, and abnormalities of interhemispheric transfer have been implicated in these patients. This study examined interhemispheric functional connectivity between auditory cortical regions, using temporal information obtained from latency measures of the auditory N1 evoked potential. Interhemispheric Transfer Times (IHTTs) were compared across 3 subject groups: schizophrenia patients who had experienced auditory hallucinations, schizophrenia patients without a history of auditory hallucinations, and normal controls. Pure tones and single-syllable words were presented monaurally to each ear, while EEG was recorded continuously. IHTT was calculated for each stimulus type by comparing the latencies of the auditory N1 evoked potential recorded contralaterally and ipsilaterally to the ear of stimulation. The IHTTs for pure tones did not differ between groups. For word stimuli, the IHTT was significantly different across the 3 groups: the IHTT was close to zero in normal controls, was highest in the AH group, and was negative (shorter latencies ipsilaterally) in the nonAH group. Differences in IHTTs may be attributed to transcallosal dysfunction in the AH group, but altered or reversed cerebral lateralization in nonAH participants is also possible.

When slow waves in the EEG delta and theta frequency range appear in the waking state, they may indicate pathological conditions including psychopathology. The generators of focal slow waves can be mapped using magnetic source imaging. The resulting brain maps may possibly characterize dysfunctional brain areas. The present study examined the stability of the density and distribution of MEG slow waves during three conditions-rest, mental arithmetic and imagery-in 30 schizophrenic patients and 17 healthy controls. Schizophrenic patients displayed a higher density of delta and theta generators primarily in temporal and parietal areas. The group difference was not affected by the particular conditions. The focal concentration of delta and theta slow waves did not differ between patients with and without neuroleptic medication, whereas the prominence of theta dipoles in the temporal area correlated with neuroleptic dosage. The relative amount of temporal slow waves was correlated with the negative symptoms score (PANSS-N) suggesting that temporal dysfunction may be related to negative symptomatology.Results suggest that the distribution of slow-wave activity, measured in a standardized setting, might add diagnostic information about brain abnormalities in schizophrenia.

De®cits of working memory (WM) are recognized as an important pathological feature in schizophrenia. Since the P600 component of event related potentials has been hypothesized that represents aspects of second-pass parsing processes of information processing, and is related to WM, the present study focuses on P600 elicited during a WM test in drug-naive ®rst-episode schizophrenics (FES) compared to healthy controls. We examined 16 drug-naive ®rst-episode schizophrenic patients and 23 healthy controls matched for age and sex. Compared with controls schizophrenic patients showed reduced P600 amplitude on left temporoparietal region and increased P600 amplitude on left occipital region. With regard to the latency, the patients exhibited signi®cantly prolongation on right temporoparietal region. The obtained pattern of differences classi®ed correctly 89.20% of patients. Memory performance of patients was also signi®cantly impaired relative to controls. Our results suggest that second-pass parsing process of information processing, as indexed by P600, elicited during a WM test, is impaired in FES. Moreover, these ®ndings lend support to the view that the auditory WM in schizophrenia involves or affects a circuitry including temporoparietal and occipital brain areas.

Objective: The aim of the present study is to assess information transmission between different cortical areas in schizophrenics by estimating the average cross mutual information (A-CMI) and to characterize the dynamical property of the cortical areas of schizophrenic patients from multi-channel EEG by establishing the auto mutual information (AMI).

This study tested whether older adults show enhanced suppression of inappropriate processing of non-target information, as marked with the nogo-P3 event-related potential (ERP). Healthy younger and older adults were tested on a simple go/nogo task with visually presented numbers. Unlike in most of the previous studies, go and nogo stimuli were matched for frequency and conflict level in order to minimize the impact of task difficulty, probability monitoring, or conflict detection and resolution on the age-related ERP differences. Older adults showed slower go responses but a comparable accuracy to younger controls. The parietal go-P3 latency was also delayed with aging, while the central nogo-P3 was more pronounced in older adults than in younger controls. The amplitude of this component negatively correlated with go-RTs. In line with previous studies, this suggests that a partial response preparation to nogo events is strongly suppressed in older adults, especially faster ones.

PERSETUJUAN ANTARA PEMERINTAH REPUBLIK INDONESIA DAN PEMERINTAH REPUBLIK TURKI TENTANG PENGHINDARAN PAJAK BERGANDA DAN PENCEGAHAN PENGELAKAN PAJAK ATAS PENGHASILAN Pasal 1 ORANG DAN BADAN DICAKUP DALAM PERSETUJUAN INI Persetujuan ini berlaku terhadap orang dan badan yang menjadi penduduk salah satu atau kedua Negara pihak pada Persetujuan.

Puberty is a critical period for the maturation of the fronto-limbic and fronto-striate brain circuits responsible for executive function and affective processing. Puberty also coincides with the emergence of the prodromal signs of schizophrenia, which may indicate an association between these two processes.Time-domain analysis and wavelet based timefrequency analysis was performed on electroencephalographic (EEG) data of 30 healthy control (HC) subjects and 24 individuals at familial risk (FR) for schizophrenia. All participants were between the ages of 13 and 18 years and were carefully matched for age, gender, ethnicity, education, andTanner Stage. Electrophysiological recordings were obtained from 32 EEG channels while participants performed a visual oddball task, where they identified rare visual targets among standard "scrambled" images and rare aversive and neutral distracter pictures. The time-domain analysis showed that during target processing the FR group showed smaller event-related potentials in the P2 and P3 range as compared to the HC group. In addition, EEG activity in the theta (4-8 Hz) frequency range was significantly reduced during target processing in the FR group. Inefficient cortical information processing during puberty may be an early indicator of altered brain function in adolescents at FR for schizophrenia and may represent a vulnerability marker for illness onset. Longitudinal assessments will have to determine their predictive value for illness onset in populations at FR for psychotic illness.

Analyzing single trial brain activity remains a challenging problem in the neurosciences. We gain purchase on this problem by focusing on globally synchronous fields in within-trial evoked brain activity, rather than on localized peaks in the trial-averaged evoked response (ER). We analyzed data from three measurement modalities, each with different spatial resolution: magnetoencephalogram (MEG), electroencephalogram (EEG) and electrocorticogram (ECoG). We first characterized the ER in terms of summation of phase and amplitude components over trials. Both contributed to the ER, as expected, but the ER topography was dominated by the phase component. This means the ER topography is akin to an interference pattern in phase across trials. Hence the observed topography of cross-trial phase will not accurately reflect the phase topography within trials. To assess the organization of within-trial phase, traveling wave (TW) components were quantified by computing the phase gradient. TWs were intermittent but ubiquitous in the within-trial evoked brain activity. At most task-relevant times and frequencies, the within-trial phase topography was described better by a TW than by the trial-average of phase. The trial-average of the TW components also reproduced the topography of the ER; we suggest that the ER topography arises, in large part, as an average over TW behaviours. These findings were consistent across the three measurement modalities. We conclude that, while phase is critical to understanding the topography of event-related activity, the preliminary step of collating cortical signals across trials can obscure the TW components in brain activity and lead to an underestimation of the coherent motion of cortical fields.

This study investigated the time-frequency dynamics of P300 generation in patients with first-onset schizophrenia. A group of 40 patients with first-onset schizophrenia and 40 controls performed an auditory oddball task. Wavelet analysis of the single-trial data was used to compute the Event-Related Spectral Perturbation (ERSP) and the Inter-Trial Phase Coherence (ITC) for the delta, theta, alpha, beta and gamma bands on the 50 ms window around peak P300 amplitude. The contribution of power and synchrony for P300 amplitudes was studied through correlation and regression analysis. Further, two sub-samples in which patients had lower or higher P300 amplitudes than their control match were contrasted. P300 amplitude did not differ between patients and controls. The frequency domain analysis revealed that controls display larger reductions on gamma power than patients. However, this gamma activity might be the result of micro-saccadic muscular artifacts. Regression analysis shows that P300 amplitude is highly dependent on delta power and synchronization. The analysis of the subsamples confirmed that while gamma power differences are dependent on the diagnosis, delta and theta synchronization are related to P300 amplitude, irrespective of diagnosis.

Changes in attention allocation with complex task learning reflect processing automatization and more efficient control. We studied these changes using ERP and EEG spectral analyses in subjects playing Space Fortress, a complex video game comprising standard cognitive task components. We hypothesized that training would free up attentional resources for a secondary auditory oddball task. Both P3 and delta EEG showed a processing trade-off between game and oddball tasks, but only some game events showed reduced attention requirements with practice. Training magnified a transient increase in alpha power following both primary and secondary task events. This contrasted with alpha suppression observed when the oddball task was performed alone, suggesting that alpha may be related to attention switching. Hence, P3 and EEG spectral data are differentially sensitive to changes in attentional processing occurring with complex task training.

Changes in personal identity have been described as a major component in the expression of schizophrenia. Considering current evidence that relates the cortical structures of the medial line with the self, we hypothesize that there are differences in the frontomedial electrophysiological activation in schizophrenics when compared to normal subjects during tasks that require this function. In an experimental design, 9 schizophrenic and 7 normal subjects participated in a personal traits attribution task regarding the attribution of the self, another person and a simple reading. Electric brain activity was recorded with a dense array of 128 electrodes, with evoked brain potentials being obtained for the three conditions. Considering the evoked potential morphology, repeated measures ANOVA were performed on the adaptive mean for the 180-230 ms time window (P200) in the frontomedial electrodes, with a group effect being found (F=5.352; p=0.038). Comparisons of the groups show that the schizophrenics presented less voltage in the self condition (t=2.386; p=0.033). Although the results are not consistent with the hypothesis, it can be suggested that the early modulation of word-related meaning formation in a self-referential context could be affected in schizophrenia.

PERSETUJUAN ANTARA PEMERINTAH REPUBLIK INDONESIA DAN PEMERINTAH KERAJAAN THAILAND MENGENAI PENGHINDARAN PAJAK BERGANDA DAN PENCEGAHAN PENGELAKAN PAJAK YANG BERHUBUNGAN DENGAN PAJAK-PAJAK ATAS PENDAPATAN DAN ATAS KEKAYAAN PEMERINTAH REPUBLIK INDONESIA dan PEMERINTAH KERAJAAN THAILAND BERHASRAT untuk mengadakan suatu Persetujuan mengenai Penghindaran Pajak Berganda dan Pencegahan Pengelakan Pajak yang berhubungan dengan Pajak-Pajak atas Pendapatan dan atas Kekayaan. TELAH MUFAKAT SEBAGAI BERIKUT : Pasal 1 Orang-orang dan badan-badan yang tercakup dalam Persetujuan ini