Small multipolar interneurons situated in the molecular layer of the cerebellum that give rise to parallel fibers, and the most numerous cell type in the brain. They are the only cell to receive inputs from outside the cerebellar cortex, the other being the Purkinje cells. In the cerebellum, there are some 100 billion such cells, which is more than there are in cerebral cortex. They excite basket, stellate and Golgi type II cells via the parallel fibers, and in turn are excited by mossy fibers and inhibited by Golgi type II cells. They send (non-myelinated) axons up to the surface of the cerebellar cortex instead of down to the white matter under the cortex (viz., to the vestibular nucleus in the brain stem). As a consequence, they propagate new impulses and send feedback toward the surface of the cerebellar cortex.
See Basket cells, Cerebellar cortex, Cerebellum (anatomy), Golgi type II cells, Granular layer, Interneurons, Molecular layer, Mossy fibers, Myelin, Parallel fibers, Purkinje cells, Stellate cells, Vestibular nuclei