Climbing fibers

Kano, M., Hashimoto, K., Kurihara, H. et al. Persistent multiple climbing fiber innervation of cerebellar Purkinje cells in mice lacking mGluRl. Neuron 18 71-79,1997. 

At the same time that the motor neurons send signals to the muscles, branches travel into other parts of the brain including the olivary nuclei, which send neurons into the cerebellum. The cerebellum acts as a kind of computer needed for fine tuning of the impulses to the muscles. Injury to the cerebellum leads to difficulty in finely coordinated motions. Input to the Purkinje cells arises from the climbing fibers, which originate in the inferior olive of the brain stem. Each climbing fiber activates a single Purkinje cell, but the dendrites of each Purkinje cell also form as many as 200,000 different synapses with parallel fibers that run across the cortex of the cerebellum (Fig. 30-15). 

Zollinger M., Brauchli-Theotokis J., Gutteck-Amsler U., Do K. Q., Streit P., and Cuenod M. (1994). Release of N-acetylaspartylglutamate from slices of rat cerebellum, striatum, and spinal cord, and the effect of climbing fiber deprivation. J. Neurochem. 63 1133-1142. 

Ito M, Kano M (1982) Long-lasting depression of parallel fiber-Purkinje cell transmission induced by conjunctive stimulation of parallel fibers and climbing fibers in the cerebellar cortex. Neu-rosci Lett 33 253-8... 

Tsou K, Brown S, Sanudo-Pena MC, Mackie K, Walker JM (1997) Immunohistochemical distribution of cannabinoid CB1 receptors in the rat central nervous system. Neurosci 83(2) 393 411 Van Beugen BJ, Nagaraja RY, Hansel C (2006) Climbing fiber-evoked endocannabinoid signaling heterosynaptically suppresses presynaptic cerebellar long-term potentiation. J Neurosci 26(32) 8289-94... 

Foster KA, Regehr WG. Variance-mean analysis in the presence of a rapid antagonist indicates vesicle depletion underlies depression at the climbing fiber synapse. Neuron 2004 43 119-131. 

The major afferent pathways to the cerebellar cortex are the mossy and climbing fiber systems. Climbing fibers establish direct contact with the Purkinje cells, whereas the mossy fibers influence the Purkinje cells indirectly, through the granule cell-parallel fiber system. The excitatory nature of each of these systems (including the parallel fibers) is well-established (Ito, 1984) and several lines of evidence point to Glu as their likely transmitter (Fig. 6). 

The climbing fibers are now believed to use glutamate as transmitter, like the major proportion of mossy fibers. They are strongly enriched in glutamate (Ottersen et al., 1992) and their terminals are apposed to Purkinje cell thorns that exhibit a high density of AMPA receptors (Landsend et al., 1997). 

Cuenod M, Do KQ, Vollenweider F, Zollinger M, Klein A, Streit P (1989) The puzzle of the transmitters in the climbing fibers. In Strata P (Ed), The Olivocerebellar System in Motor Control. Berlin Springer, pp 162-176. 

Landsend AS, Amiry-Moghaddam M, Matsubara A, Bergersen L, Usami S, Wentbold RJ, Ottersen OP (1997) Differential localization of glutamate receptors in the rat cerebellum coexpression with AMPA receptors in parallel fiber-spine synapses and absence from climbing fiber-spine synapses. J Neurosci /7 834 842. 

Tbggenburger G, Wiklund L, Henke H, Cuenod M (1983) Relea.se of endogenous and accumulated amino acids from slices of normal and climbing fiber-deprived rat cerebellar slices. J Neurochem 4/ 1606-1613. 

Vollenweider FX, Cuenod M, Do KQ (1990) Effect of climbing fiber deprivation on release of endogenous aspartate, glutamate, and homocysteate in slices of rat cerebellar hemispheres and vermis. J Neurochem 54 1533-1540. 

Wiklund L, Toggenburger G, Cuenod M (1984) Selective retrograde labelling of the rat olivocerebellar climbing fiber system with D-[ H]asparate. Neuroscience 75 441-468. 

Flint RS, Rea MA, McBride WJ (1981) In vitro release of endogenous amino acids from granule cell-, stellate cell-, and climbing fiber-deficient cerebella. J Neurochem 37 1425-1430. 

Zhang N, Ottersen OP (1993) In search of the identity of the cerebellar climbing fiber transmitter immunocyto-chemical studies in rats. Can J Neurol Sci 3 36-42. 

Zhao HM, Wenthold RJ, Wang YX, Petralia RS (1997) 8-Glutamate receptors are differentially distributed at parallel and climbing fiber synapses on Purkinje cells. J Neurochem 68 1041-1052. 

Fig. 6. Summary histogram of development of glutamate receptors at parallel [postnatal day 10 (PI0) to adult] and climbing (P2 to adult) fiber synapses on Purkinje cells of the cerebellum. Note especially the peak in immunogold labeling of the delta receptors at PI0-PI4 in climbing fiber synapses (cO, the peaks of the AMPA receptors (GluR2, GluR2/3 antibodies) at P2-P5, and the inverse patterns of peaks for parallel fiber synapses (pf) and climbing fiber synapses in adults for AMPA versus delta receptors. Modified from Zhao et al. (1998).

In the adult cerebellum, as noted above, parallel fiber synapses have abundant delta receptors, while delta receptors are rare or absent from climbing fiber synapses. AMPA receptors are found at both excitatory synapse populations but are more abundant at climbing fiber synapses. In the first postnatal week, presumptive climbing fiber synapses have high... 

Petralia RS, Zhao H-M, Wang Y-X, Wenthold RJ (1998) Variations in the tangential distribution of postsynaptic glutamate receptors in Purkinje cell parallel and climbing fiber synapses during development. Neuropharmacology 37 32l- 3M. 

Otis TS, Kavanaugh MP, Jahr CE (1997) Postsynaptic glutamate transport at the climbing fiber Purkinje cell synapse. Science 277 1515-1518. 

Marin-Padilla M (1985) Neurogenesis of the climbing fibers in the human cerebellum a Golgi study. J Comp Neurol 235 82-96. 

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