Cortical circuit dysfunction in the NMDA receptor hypofunction model for the psychosis of schizophrenia

The psychosis of schizophrenia can often be striking in its presentation, in large part due to the bizarreness of psychotic behavior and thinking. It is nonetheless an extremely subtle dysfunction that has proven remarkably difficult to define. The most widely recognized cognitive deficit associated with schizophrenia is a working memory abnormality. Cognitive deficits assessed by the more traditional neuropsychological tests, including the Wisconsin Card Sort and Stroop tests indicate abnormalities consistent with dysfunction of working memory systems although these tests may be affected by the functionality of other systems. Tests, selective for working memory dysfunction, revealed deficits in spatial but not verbal working memory, in schizophrenic patients (Park et al. 1995). A dysfunctional spatial working memory may contribute to the core psychotic symptoms of thought disorder and delusions but does not seem sufficient to account for them.