Influences of cerebellar hemispherectomy upon cortical potentials preceding visually initiated hand movements in the monkey.

With chronically implanted electrodes, surface and depth potentials of the premotor and motor cortices were recorded on hand movements in response to a visual stimulus in monkeys, and influences of cerebellar hemispherectomy were examined upon visually initiated premovement cortical potentials. Early, surface positive--depth negative premovement potentials emerged in the cortices on both sides, and following surface negative--depth positive premovement potentials appeared in the motor cortex contralateral to the moving hand. Cerebellar hemispherectomy contralateral to the motor cortex eliminated the following potentials. This suggests the participation of the neocerebellum in preparing the motor cortex for visually initiated movements.