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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a pilot study, the P300 component of the ERP subsequent to competitive visual stimulation was examined in 12 schizophrenic patients (paranoid hallucinatory schizophrenia in partial remission, neuroleptic medication). In the competitive stimulation with a varying information content of the non-target stimuli, healthy probands showed a distinct increase in the amplitude of the P300 components according to a in the frequency of the non-target stimuli. The P300 components during these changing stimulatory conditions remained constant in the schizophrenic patients. This reduction in the reactivity of the P300 component subsequent to an increasing information content of the non-target stimuli can be interpreted as a disturbance in the selective information processing. The ability to adequately react to the information content of irrelevant stimuli appears to be reduced in the schizophrenic patients we examined.
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PMID:The P300 component of event-related potentials in schizophrenic patients. 342 84

The P300 component was elicited by an auditory oddball paradigm in 55 normal adults from a wide age range: 19 patients with dementia, 17 patients with depression, and 15 patients with schizophrenia. Normal P300 latency at a given age was predicted by using an age regression equation that had been calculated on the basis of the entire normal sample. Using this procedure, an abnormal delay in latency (greater than 2 SD) was found in approximately 80% of the dementia patients. However, when normal latency was predicted with a slightly greater degree of reliability according to separate equations for adults younger and older than 63 years, an abnormal delay in P300 was found to be less sensitive and specific to dementia. Suggestions for enhancing the diagnostic utility of the P300 component are proposed.
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PMID:The differential diagnosis of dementia using P300 latency. 375 62

Psychophysiological anomalies in symptomatic schizophrenic patients, remitted schizophrenic patients, and individuals at heightened risk for a schizophrenic disorder are reviewed with an emphasis on electrodermal anomalies. Two electrodermal anomalies are identified in different subgroups of symptomatic patients: (1) an abnormally high sympathetic arousal and (2) an abnormal absence of skin conductance orienting responses to innocuous environmental stimuli. The same two electrodermal anomalies also have been observed in remitted schizophrenic patients. Among high-risk individuals, the offspring of schizophrenic patients display abnormally high electrodermal responsiveness to aversive stimulation, whereas a substantial proportion of college students who score high on physical anhedonia (a putative risk factor for schizophrenia) exhibit skin conductance nonresponsiveness. Thus, heightened sensitivity to aversive stimulation appears to be associated with a genetic vulnerability to schizophrenia, while tonic hyperarousal , which occurs in subgroups of symptomatic and remitted schizophrenic patients, may reflect a later developmental consequence of the underlying vulnerability. Skin conductance nonresponsivity may represent a different developmental consequence associated with the same underlying vulnerability or it may represent a different type of vulnerability. Other psychophysiological anomalies also are promising indicators of the vulnerability to schizophrenia (e.g., deviant smooth pursuit eye movements, attenuated P300 component of the event-related brain potential, reduced electroencephalic (EEG) alpha activity, and heightened EEG delta activity).
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PMID:Psychophysiological dysfunctions in the developmental course of schizophrenic disorders. 672 10

Schizophrenic patients have been observed to have a significantly diminished P300 component of the event-related potential (ERP). We investigated whether this result would be obtained with high-incentive stimuli. We presented 14 unmedicated patients and 14 controls with two easily identified visual stimuli under three conditions: (i) a nonincentive condition, (ii) under the condition of $1 payment for each correct identification, and (iii) under the condition of $1 payment for each correct identification within a criterion time. The patients responded accurately but showed a significantly reduced P300 in the incentive conditions. We interpret our results as neurophysiological evidence for possible limbic system dysfunction in schizophrenia.
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PMID:Event-related brain potentials to high-incentive stimuli in unmedicated schizophrenic patients. 687

Twenty-three schizophrenic patients and 26 age-matched control subjects were studied using the P300 recorded during the auditory oddball task, with counting. Our aim was to assess the most suitable method of measurement and analysis of P300 amplitude and latency for use in clinical studies of schizophrenia. The effect of high-pass filtering, peak definition method and recording electrode site were all investigated. We have developed a technique, based on a least-mean-squares approximation to data, which seems particularly well suited to dealing with multi-peak P300 complexes. We have also investigated the spectral composition of the P300 and have found some evidence to support a proposed 2-frequency model of the P300 complex.
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PMID:Methodological considerations in measurement of the P300 component of the auditory oddball ERP in schizophrenia. 751 Jun 27

To further explore the hypothesis that schizophrenics are more distractable and/or have reduced processing resources available, event-related potentials (ERPs) and smooth pursuit eye movements (SPEM) were investigated in 20 medicated schizophrenics, 19 detoxified chronic alcoholics, and in a control group of 20 healthy subjects. Groups were matched for age and education. Eye tracking tasks and auditory oddball tasks were performed separately as well as simultaneously. In addition, an eye tracking condition with a task-irrelevant tone sequence was used to assess the effect of distraction. Schizophrenics showed a trend for poorer SPEM performance; alcoholics had no dysfunction in this task. Tracking accuracy did not change in either group when additional auditory stimuli were presented. P300 latency was delayed in both schizophrenics and alcoholics. P300 amplitude showed no overall group difference but it increased during the dual task in normals whereas it remained constant in patients. N100 amplitude was generally larger during the more complex conditions indicating heightened unspecific arousal. It is suggested that normals use increased arousal to mobilize additional resources and to allocate them to stimulus evaluation but schizophrenics and alcoholics are unable to do so. Results are more conform to a limited resources concept than to a filter deficit model of cognitive disturbances in schizophrenia and alcoholism.
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PMID:Information processing during eye tracking as revealed by event-related potentials in schizophrenics, alcoholics, and healthy controls. 757 68

Our laboratory has repeatedly found a left < right auditory P300 temporal lobe topographic asymmetry in right-handed, medicated schizophrenics. To determine whether this asymmetry was attributable to the effects of antipsychotic medications, we collected auditory "odd-ball" P300 event-related potentials from 14 right-handed, unmedicated schizophrenics (withdrawn from medication for an average of 21 days) and 14 right-handed, normal controls. Analysis of normalized P300 amplitudes showed a statistically significant difference in the voltage distributions between groups (a group by temporal electrode site interaction) that was consistent with a left < right temporal voltage asymmetry in schizophrenics but not in the normal controls. We conclude that P300 topographic asymmetries are present in unmedicated schizophrenics. These data are compatible with the growing body of data suggesting left temporal lobe structural abnormalities in schizophrenia.
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PMID:P300 topographic asymmetries are present in unmedicated schizophrenics. 768 89

The auditory P300 event-related potential (ERP) and performance on neuropsychological tests were evaluated in 26 subjects with schizophrenia, 19 with bipolar affective disorder, and 27 controls. The schizophrenic and the bipolar groups were similar in having prolonged P300 latency recorded from central and temporal leads. The P300 was significantly reduced in amplitude in the schizophrenic group at midline leads and the left temporal lead but was not significantly reduced in amplitude at any electrode site when the bipolar group was compared to controls. Schizophrenics performed significantly less well than bipolars and controls on tests of verbal fluency and, within this group, a significant correlation was found between the latency of P300 and verbal fluency test scores. While the bipolar group of patients was similar to the schizophrenic group in having prolonged P300 latency, these groups differed in P300 amplitude, performance on verbal fluency tests, and the relationship between the physiological and neuropsychological variables.
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PMID:Auditory P300 event-related potentials and neuropsychological performance in schizophrenia and bipolar affective disorder. 774 81

Evoked cortical activity in response to acoustic stimuli (oddball paradigm) was studied in patients with different paranoid disorders. The analysis covered the N150 negative wave and positive complex P300. In patients with paranoid schizophrenia and paranoid form of involutional psychosis cortical responses to the stimuli and cortex effects were not recorded. Such cognitive deficiency is believed to be typical for schizophrenia.
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PMID:[The characteristics of the cognitive defect in patients with different variants of late paranoia]. 777 97

Single photon emission tomography with the intravenous blood flow marker 99mTc-exametazime was carried out in 14 acutely ill drug-free schizophrenic patients from whom P300 event-related potential, smooth eye pursuit eye tracking and verbal fluency were measured within a few days of scanning. Smooth pursuit eye movement abnormality correlated significantly with abnormal tracer uptake in superior pre-frontal cortex on the right and left and inferior pre-frontal cortex on the left. Abnormal eye movement was also associated with higher tracer uptake in left anterior cingulate and left posterior cingulate. P300 latency was significantly correlated with higher tracer uptake in left superior pre-frontal and left parietal regions. Verbal fluency performance was negatively correlated with tracer uptake in left frontal region. Eye tracking abnormality in schizophrenia is associated with bilateral frontal lobe disturbance and P300 latency increase with left-sided frontal and temporoparietal dysfunction. There was, however, a significant inverse relation between eye tracking abnormalities and abnormal perfusion in the left anterior cingulate region.
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PMID:Correlation of regional cerebral blood flow equivalents measured by single photon emission computerized tomography with P300 latency and eye movement abnormality in schizophrenia. 781 Mar 38


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