Event-related potential study of illusory contour perception in schizophrenia

Schizophrenic patients and healthy controls participated in event-related potential experiments, in which illusory contour (IC) and control objects [no contour (NC), real contour (RC)] were passively presented. As a result, P100 latency for IC in schizophrenic patients was significantly prolonged (+10.6 ms) compared to those for RC. The present findings indicate that an abnormality of IC processing, including 'bottom-up' as well as 'top-down' processing, may reflect basal pathogenesis of various clinical representations of schizophrenia. However, the P100 latency difference between IC and RC was very small in the patient group. Rather, 'cognitive' in the Positive and Negative Syndrome Scale (PANSS) model of Bell et al. significantly correlated with P100 latencies for NC. Such an association between PANSS and NC processing, where the shape must be inferred with increased attentional demands and 'top-down' processing, indicates that the abnormality of schizophrenic patients' preattentive process might be a problem of 'top-down' processing rather than 'bottom-up' processing.