no go task in schizophrenia

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CONSTRUCT VALIDATION OF AUDITORY EVENT-RELATED POTENTIAL INDICES OF FRONTAL AND TEMPORO-PARIETAL INFORMATION PROCESSING IN SCHIZOPHRENIA SYNDROMES U. Schall*, F. Karayanidis, P.B. W a r d

Biological Schizophrenia Research Team, University o['New South Wales School ~["Psychiatr.v, The Prince of Wales Hospital Sydney, Australia," *Biological Psychiatry Research Group, University Cliniejor Adult Psyehiato,, 45147 Essen, Germany Back~,,round/hypothesis: Schizophrenia syndromes are associated with unusual anatomically circumscribed brain function [1]. The corresponding cognitive deficit can be quantified by event-related potential (ERP) measures. Methods: Specificity, construct and predictive validity of ERP factor scores (principle component analysis; varimax rotation) of automatic and active auditory information processing (mismatch negativity, MMN; recorded at Fz), novelty P3a (recorded at Fz under ignore and attend conditions), and target-P3b (at Pz) were evaluated in 25 schizophrenic patients and 21 healthy subjects. Syndrome factor scores were calculated on the bases of SAPS/SANS symptom-ratings in patients. Results: Two ERP factors were extracted in healthy subjects: ( l ) 'Novelty Reaction' with high loading scores for P3a and t2) 'Deviant Detection' representing MMN and P3b. Schizophrenic patients were correctly classified on the bases of the factor structure of healthy subjects in 69.6% of the cases (p=0.01). Low composite scores on 'Deviant Detection' were associated with negative symptoms: this may indicate frontal brain dysfunction. "Novelty Reaction' was more closely related to thought disorder, bizarre behaviour and delusions, indicating a potential temporo-parietal dysfunction. The clinical response to clozapine was followed-up over 3 years in 17 patients and was predicted correctly on the bases of the pre-treatment ERP factor composites in 94.1% of cases (p < 0.01 ). Conclusions: ( 1 ) ERP indices of automatic and active auditory information processing are associated with separate schizophrenic syndromes and are thus indicative of underlying brain dysfunction. (2) Poor response to atypical neuroleptics is dependent on the severity of brain impairment. R~Jerenee I. Liddle et al. (1992) Br J Psychiat, 160. 179-186.

EVENT GO/NO

RELATED POTENTIALS DURING GO TASK IN SCHIZOPHRENIA

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A n d r a M. Smith, Kent A. Kiehl, Peter F. Liddle

Department o['Psyehiatry. University ~ff'British Columbia, 2255 Wesbrook Mall, Vancouver, V6T2AI, Canada Neuropsychological and brain imaging studies have indicated that the disorganisation of thought, affect and behaviour that

occurs in schizophrenia arises from malfunction of the neural circuits involved in the selection of mental activity. In this study, we tested the hypothesis that schizophrenia is associated with abnormal neural processing during the suppression of inappropriate responses. We recorded event related potentials (ERPs) in 11 schizophrenic patients and 10 healthy controls during performance of a Go/No Go task. There were no group differences in the behavioural performance of this task. Control subjects showed the expected early frontal negativity, but this effect was greatly reduced in the schizophrenics. In the control subjects, Go trials were associated with a larger posterior P300 than No-Go trials, but this difference was absent in schizophrenics. These findings suggest that a deficit in frontal lobe activity in schizophrenia results in failure to suppress inappropriate processing during the No-Go trials, even under circumstances where the behavioural performance is not impaired.

POLYSOMNOGRAPH1C IN SCHIZOPHRENIA:

ABNORMALITIES A REPLICATION

R. Tandon, S. Maixner, A. Eiser, J.E. Shipley, S.F. Taylor, J.R. D e Q u a r d o

Schizophrenia Program. University ~/' Miehigan Ho.~pitals, Ann Arbor, M148109-0120. USA Although there have been several sleep-electroencephalographic (EEG) studies in schizophrenia, the precise polysomnograpbic profile in schizophrenia is still undefined. While a vast majority of studies document disruption in sleep continuity, there is less agreement on the presence of shortening of rapid-eye-movement (REM) latency and reduction in slowwave sleep (SWS) in schizophrenic patients. We have previously reported that both drug-naive and previously-medicated schizophrenic patients exhibit disrupted sleep continuity and shortening of REM latency when compared to healthy controls (Tandon et al. 1992); we also observed that REM latency was inversely correlated to the severity of negative symptoms. To replicate these findings, we recorded EEG sleep in another sample of 39 medication-free (minimum 2 weeks) schizophrenic patients (DSM-III-R and SADS/RDC) and 25 healthy controls. The two groups were similar in age and gender distribution. We observed a significant disruption in sleep continuity in the schizophrenic group as characterized by increased sleep latency, more minutes awake after falling asleep, more arousals, less time spent asleep, and reduced sleep efficiency and maintenance. Stage 1% sleep was increased and SWS was significantly decreased: no difference in %REM sleep was observed. REM latency was significantly decreased (mean = 57 minutes in the schizophrenia group versus 89 minutes in the healthy control group): other REM measures were similar between the two groups except for REM density in the first REM period which was increased in the schizophrenia group. Findings were similar in the neuroleptic-naive (n = 18 ) and previously-medicated (n = 21) schizophrenic groups. REM latency, but not SWS, was found to be significantly and inversely correlated with the severity of negative symptoms. These data confirm a polysomnographic profile in schizophrenia characterized by disrupted sleep continuity, decreased slow-wave sleep, and reduced REM