The influence of threatening stimuli on the evoked potential component P200 in patients with paranoid schizophrenia

Abstract

Evoked potentials (EPs) of the brain in response to visual neutral and emotionally meaningful (threatening) stimuli were studied in order to clarify neurophysiological disturbances of affective perception during the psychotic state in schizophrenic patients with severe paranoid–hallucinatory syndrome who did not receive neuroleptic therapy. Analysis of the P200 component in a group of healthy subjects showed an increase in the amplitude and shortening of the latency of this wave in response to threatening stimuli compared to neutral ones. In the group of patients with schizophrenia, as well as in healthy subjects, the P200 component analysis showed an increase in the level of excitation in response to emotionally threatening stimuli. However, patients with schizophrenia were found to have areas where both the amplitude and latency were decreased or increased at the same time. The results suggest that schizophrenic patients are characterized by the pathological effect of simultaneously having the EPs parameters characteristic of both excitation and inhibition processes.