EEG coherence of prefrontal areas in normal and schizophrenic males during perceptual activation.

Multiple studies have demonstrated prefrontal dysfunction among schizophrenics. The prefrontal cortex does not function in isolation, but instead relies on extensive connections with other brain areas. Functional relationships between cortical areas were assessed by calculating the coherences between different scalp electroencephalogram (EEG) signals recorded from 13 unmedicated male patients with schizophrenia and 9 normal male subjects. Alpha-band coherences linked to prefrontal areas in schizophrenic patients were about the same as those of normal controls when subjects were cognitively "at rest," but they were reduced for certain electrode pairs in the former group when performing the degraded-stimulus continuous performance test. Most of these findings were not accounted for by changes in alpha power, suggesting that "cortical circuits" extending beyond prefrontal areas may be disrupted in schizophrenia.