Having their origins in the pontocerebellarm, spinocerebellar and vestibulocerebellar pathways, they are one of two afferent excitatory inputs to the cerebellum that release the depolarising neurotransmitter glutamate, which indirectly activate Purkinje cells through their direct connections with Golgi type II interneurons and granule cells (one of the interneurons in the cerebellar cortex) in the granular layer, the latter forming part of a disynaptic pathway to the Purkinje cell. Each fiber has 3-5 synapses, shaped like rosettes, with each dendrite of a granular cell. Physiological evidence suggests that mossy fibers inform the cerebellar cortex about the position and rate of movement of the limbs.
See Cerebellum (anatomy), Cerebellum (functions), Climbing fibers, Golgi type II cells, Glutumate (or glutamate), Granular layer, Granule cells, Interneurons, Purkinje cells