Anatomy of the cerebellum a narrow midline zone called the "vermis". A set of large folds are conventionally used to divide the overall structure into ten smaller lobules. Because of its large number of tiny granule cells, the cerebellum contains more neurons than the rest of the brain put together, but it only takes up 10% of total brain volume. The cerebellum receives nearly 200 million input fibers; in contrast, the optic nerve is composed of a mere one million fibers. The unusual surface appearance of the cerebellum conceals the fact that the bulk of the structure is made up of a very tightly
Anatomy of the cerebellum cerebellar cortex. Under resting conditions in animal experiments, groups of olivary neurons discharge synchronously at 5 to 10 Hz (impulses/s). In the cerebellar cortex, the response of Purkinje cells takes the form of complex spikes. The cerebellum send its projections back to the cerebral cortex via the Cerebellothalamic tract. The cerebellar lateral expansion, or the neocerebellum, may be associated with cognitive functions, and it is anatomically linked with the lateral prefrontal cortex. It shows greatest activity during speech, with a one-sided predominance consistent with a possible linkage (via the thalamus) with the motor speech area. When lesions occur in the