Electrophysiological evidence for reduced latent inhibition in schizophrenic patients

Author(s): vonRecum, S., Haag, C., Engel, R. R.

Journal/Book: Schizophr Res. 2000; 45: PO Box 211, 1000 AE Amsterdam, Netherlands. Elsevier Science Bv. 103-114.

Abstract: The present study examined latent inhibition (LI) effects in 17 acute and 16 partially remitted schizophrenic patients, and in 20 healthy controls, by measuring manual response latencies and event-related potentials (ERPs) during an association learning task. ERPs were recorded to elucidate the role of attention in the LI effect. Subjects performed a go/no-go task with an auditory conditional stimulus predicting a visual go command. Half of the subjects in each diagnostic group were pre-exposed to the conditional stimulus which had been used as an irrelevant distracter in a preceding discrimination task. Independent of diagnostic group membership, pre-exposed subjects showed slower manual responses to go stimuli than non-pre-exposed subjects, reflecting a robust LI effect. The N100 wave after the conditional stimuli, however, showed a differential pattern: pre-exposure increased N100 amplitudes in acute schizophrenics, whereas pre-exposed control subjects showed a trend for decreased N100. The amplitude of the contingent negative variation (CNV) was unaffected by pre-exposure. The ERP results suggest that acute schizophrenics have a deficit in learned inattention to irrelevant stimuli. However, the intact LI effect in schizophrenics at the motor speed level shows that human LI is a complex phenomenon depending on the tasks and measures used.

Note: Article Kathmann N, Univ Munich, Dept Psychiat, Nussbaumstr 7, D-80336 Munich, GERMANY

Keyword(s): association learning; event-related brain potentials; latent inhibition; reaction time; schizophrenia; EVENT-RELATED POTENTIALS; HEALTHY CONTROLS; PREEXPOSURE; STIMULI; AMPHETAMINE; ATTENTION; DURATION; DOPAMINE; HUMANS; TASK

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