The Cerebellum and Movement Precision

Abstract

The cerebellum is essential for the full perfection of a wide variety of bodily movements. Once considered to be “the head ganglion of the propriosensory system,” it is now apparent that the cerebellum contrib- utes to all brain activities that are ultimately expressed in movement. To accomplish this role, the cerebellum receives sensory information of all kinds (except, perhaps, visceral, olfactory, and taste) from all parts of the body, information about motor commands from the descending systems, and a diversity of reprocessed information from higher brain structures, including, most prominently, the cerebral cortex. In turn, the cerebel- lum’s output is sent to all of the motor control systems of the brain. The cerebellum is best known clinically for its contribution to the coordination of skeletomotor movement; clinical signs of cerebellar dysfunction are ataxia of limb and eye movements, postural disturbances, and decreased muscle tone. In this chapter, let’s examine the cerebellar processing circuit and see how its design enables it to contribute precise timing to specific muscle contractions.