SCHIZOPHRENIA AND COGNITIVE DYSMETRIA - A POSITRON-EMISSION TOMOGRAPHY STUDY OF DYSFUNCTIONAL PREFRONTAL-THALAMIC-CEREBELLAR CIRCUITRY

Patients suffering from schizophrenia display subtle cognitive abnorma lities that may reflect a difficulty in rapidly coordinating the steps that occur in a variety of mental activities. Working interactively w ith the prefrontal cortex, the cerebellum may play a role in coordinat ing both motor and cognitive performance. This positron-emission tomog raphy study suggests tile presence of a prefrontal-thalamic-cerebellar network that is activated when normal subjects recall complex narrati ve material, but is dysfunctional in schizophrenic patients when they perform the same task. These results support a role for the cerebellum in cognitive functions and suggest that patients with schizophrenia m ay suffer from a ''cognitive dysmetria'' due to dysfunctional prefront al-thalamic-cerebellar circuitry.