Pontine nuclei-mediated cerebello-cerebral interactions and its functional role.

The pontine nuclei relay information derived from the cerebral cortex to the cerebellum. In addition to the motor command signals generated in the motor cortex, the cerebellum may generate motor command signals independent of the cerebral cortex using pontine nuclei-mediated signals. The cerebellar motor command signals generated in the vermis-medial cerebellar nuclear system may directly drive peripheral motoneurons in simple and autonomic movements. Those generated in the hemisphere-lateral cerebellar nuclear system, which are used in complicated movements, may not only drive the premotor or motor nuclei but may also be fed back to the cerebellum through the parvocellular red nucleus-inferior olive pathway, and may be compared with the motor command signals generated in the cerebral cortex. The long-term depression of parallel fiber-Purkinje cell synapses may be utilized in optimizing these cerebellar motor command signals. Voluntary movements may be executed through cooperation of the cerebellum- and cerebrum-generated motor command signals.