THE COMPARTMENTALIZATION OF THE CEREBELLUM

The concept of developmental compartments originated in studies of Dro sophila embryogenesis. This review examines the hypothesis that the mo dular structure of the vertebrate cerebellum is strongly analogous to this earlier scheme. The pattern of cerebellar development, the adult circuitry, a variety of molecular markers expressed in specific subdiv isions, and the phenotypes of several neurological mutations all provi de abundant evidence that the vertebrate cerebellum is organized into modules. We present the case that, as a group, these markers reveal di stinct boundaries that partition the cerebellum into true developmenta l compartments. Although this reductionist viewpoint advances our unde rstanding of cerebellar organization, the relationship between these c ompartments and the functional behavior of the cerebellum remains a my stery.