Climbing fiber

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Climbing fiber
Microcircuitry of the cerebellum. Excitatory synapses are denoted by (+) and inhibitory synapses by (-). Climbing fiber is shown originating from the inferior olive (green).
Location	Inferior Olive and Cerebellum
Function	Unique excitatory function (see text)
Morphology	Unique projection neuron (see text)
Presynaptic connections	Inferior olive
Postsynaptic connections	Purkinje cells
Gray's	subject #187 796

Climbing fibers 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 climbing fiber will form synapses with 1-10 Purkinje cells.

Early in development, Purkinje cells are innervated by multiple climbing fibers, but as the cerebellum matures, these inputs gradually become eliminated resulting in a single climbing fiber input per Purkinje cell.

These fibers provide very powerful, excitatory input to the cerebellum which results in the generation of complex spikes in Purkinje cells.

Climbing fiber activation is thought to serve as a motor error signal sent to the cerebellum, and is an important signal for motor learning.

These Climbing fibres carry information to various sources such as the spinal cord, vestibular system, red nucleus, superior colliculus, reticular formation and sensory and motor cortices.

[edit] External links

• Neuroanatomy at UW cere/text/P4/climb.htm