Mossy-fibre sensory input to the cerebellum.

The role of the spinal and vestibular afferents to the cerebellum in the control of movement first began to be recognized towards the end of the 19th century. By the middle of the present century it was clear that visual and auditory information are also relayed to the cerebellum from the cerebral cortex and brainstem by way of the pontine nuclei. Pontine cells project to the cerebellar cortex where they terminate as mossy fibres. The corticopontine projection arises from cells in lamina V of the cerebral cortex. Cells in the rat primary somatosensory cortex also provide an input to the basal ganglia, but the two populations are largely segregated in distinct sub-laminae. In monkeys, and probably in humans, the cortical visual input to the pontine nuclei arises from the dorsal stream of extrastriate visual areas. Experimental and clinical evidence suggest that damage to this pathway at the cortical level, or interruption of its corticopontine fibres within the internal capsule produce profound disturbance in visuomotor guidance. One of the major pathways through the brain for the visual guidance of movement is relayed from the dorsal stream of extrastriate areas to the cerebellum by way of the pontine nuclei.