The cerebellum is known to be the place in the brain where learned movements are stored. Because of this, it has a large amount of control over the coordination of movements. But exactly how is this control exerted? First, the cerebellum receives input from various other parts of the brain (and spinal cord). One such brain part is called the inferior olive, which itself receives sensory information from many parts of the brain and spinal cord. It then relays this info to the cerebellum. In the cerebellum, the data are analyzed and a course of action is quickly decided. To put this action into play requires the output of information from the cerebellum and this is where specialized nerve cells called Purkinje cells become very important. Each and every piece of information that leaves the cerebellum does so through the Purkinje cells. Hence, these cells have a great deal of control over the refinement of motor activities. (See Figure F-8.)
Given this mechanism for the cerebellum’s control over movement, it’s no wonder that when there is severe damage to Purkinje cells and nerve cells in the inferior olive, the symptoms of ataxia (including the aforementioned loss of coordination and difficulty with speech) begin to show.
Last Modified: 9-13-02