Aberrant interhemispheric alpha coherence on electroencephalography in schizophrenic patients during activation tasks.

Thirty schizophrenic patients (20 medicated, 10 off medication) were compared with 30 normal controls subjects matched for age, sex, handedness and intelligence. During the performance of a frontal activation task, normal subjects showed increased interhemispheric coherence between anterior brain regions. Schizophrenic patients did not show the same amount of bilateral anterior activation. During the performance of right hemisphere cognitive activation tasks, normal subjects and medicated schizophrenic patients showed significantly reduced bilateral interhemispheric coherence patterns, while the drug-free schizophrenic patients showed a trend towards this same pattern. It is suggested that these findings provide additional evidence for an aberrant functional organization of the brain in schizophrenia.