Reduced attention-related negative potentials in schizophrenic adults.

Event-related potentials were recorded from outpatient adult schizophrenics receiving maintenance doses of neuroleptics and from normal control subjects during performance of a reaction time task and a complex visual discrimination task, the Span of Apprehension. Difference potentials were computed to isolate endogenous activity associated with the processing demands of the Span task. Schizophrenics produce significantly less early endogenous negative activity than do normal subjects. This processing-related negativity reflects pattern matching activity to an attentional trace during the serial scan of the visual icon. We previously reported an identical reduction in processing-related negativity in childhood-onset schizophrenia, suggesting that this deficit is age independent. Both frontal contingent negative variation and an early frontal P3 were larger in the schizophrenics than in normal subjects, suggesting an inappropriate mobilization of nonspecific attentional resources. A later posterior P3 was significantly smaller in schizophrenics than in normal subjects.