Aberrant high-frequency desynchronization of cerebellar cortices in early-onset psychosis.

Sensorimotor integration deficits are routinely observed in both schizophreniform and mood-disordered psychoses. Neurobiological theories of schizophrenia and related psychoses have proposed that aberrations in large-scale cortico-thalamic-cerebellar-thalamic-cortical loops may underlie integration abnormalities, and that such dysfunctional connectivity may be central to the pathophysiology. In this study, we utilized a basic mechanoreception task to probe cortical-cerebellar circuitry in early-onset psychosis. Ten adolescents with psychosis and 10 controls completed unilateral tactile stimulation of the right and left index finger, as whole-head magnetoencephalography (MEG) data were acquired. MEG data were imaged in the frequency domain, using spatial filtering, and the resulting event-related synchronizations and desynchronizations (ERS/ERD) were subjected to voxel-wise analyses of group and task effects using statistical parametric mapping. Our results indicated bilateral ERD activation of cerebellar regions and postcentral gyri in both groups during stimulation of either hand. Interestingly, during left finger stimulations, adolescents with psychosis exhibited greater alpha and gamma ERD activity in right cerebellar cortices relative to controls. Subjects with psychosis also showed greater ERD in bilateral cerebellum and the right postcentral gyrus during right finger stimulation, and these differences were statistically stronger for higher frequency bins. Lastly, controls exhibited greater alpha ERS of the right postcentral gyrus during right finger stimulation. These findings provide new data on the neurodevelopmental trajectory of basic mechanoreception in adolescents, and also indicate aberrant cerebellar functioning in early-onset psychoses, especially in the right cerebellum, which may be the crucial dysfunctional node in cortico-thalamic-cerebellar-thalamic-cortical circuits.