<unk> s are the name given to a series of neuronal projections from the inferior olivary nucleus located in the medulla.
These axons pass through the pons and enter the cerebellum where they form synapses with the deep cerebellar nuclei and Purkinje cells. Each<unk>  will form synapses with 1-10 Purkinje cells.
Early in development, Purkinje cells are innervated by multiple<unk> s, but as the cerebellum matures, these inputs gradually become eliminated resulting in a single<unk>  input per Purkinje cell.
These<unk> s provide very powerful, excitatory input to the cerebellum which results in the generation of complex spikes in Purkinje cells.<unk>  activation is thought to serve as a motor error signal sent to the cerebellum, and is an important signal for motor timing.
These<unk> es carry information to various sources such as the spinal cord, vestibular system, red nucleus, superior colliculus, reticular formation and sensory and motor cortices.
Climbing fiber
Association fiber
Reticular fiber
James fibers
Vesicle 
Muscle fascicle
Intermediate filament
Dendrite