Cerebellum: Anatomy and Organisation

Abstract

The cerebellum is a highly stereotyped cortical structure in the hindbrain of all vertebrates from fish to primates. The circuitry of the cerebellar cortex is built around the large, inhibitory Purkinje cells, which are the focus of all afferent input to the cerebellar cortex and are modulated by several classes of inhibitory interneuron (basket, stellate, Golgi and Lugaro cells). Despite the apparent homogeneity of the cerebellar circuitry, the cerebellum is highly modular, comprising several hundred discrete and reproducible anatomical and physiological units (‘stripes’). Each stripe receives precise afferent inputs – climbing fibres directly to the Purkinje cells and mossy fibres indirectly via the granule cells. In turn, the Purkinje cells send efferent projections to specific targets in the cerebellar and vestibular nuclei. As a result, within the cerebellum a wide variety of sensory information is brought together and integrated, primarily to aid in motor control. Key Concepts: Cerebellar circuitry is built around the Purkinje cell. The cerebellar cortex is divided into an array of transverse zones and parasagittal stripes. The cerebellar cortex receives two major afferent inputs – climbing fibres and mossy fibres. Purkinje cells are the sole efferent projections of the cerebellar cortex. Multiple interneurons modulate Purkinje cell firing patterns.