Afferent connections of the inferior olive

Afferent systems of the inferior olive have been reviewed by Brodal and Kawamura (1980) for the cat and by Martin et al. (1980) for the opossum. For the rat the tabulated summary of its afferent connections in the paper of Brown et al. (1977) and the review by Flumerfelt and Hryccyshyn (1985) are useful. Afferent systems of the inferior olive can be subdivided into three groups (1) the GABAergic nucleo-olivary and vestibulo-olivary projections (2) the monoaminergic and cholinergic projections to the inferior olive (3) the specific projections from the spinal cord, certain brain stem nuclei and the cerebral cortex will not be considered in this chapter. Their neurotransmitters are not known. 

The nucleo-olivary and vestibulo-olivary projections The GABAergic afferents of the inferior olive 

GAD-immunoreactive boutons disappear from the contralateral PO, the rostral MAO and the lateral half of the ventral fold of the DAO of the rat after chronic lesions of the cerebellar nuclei or the superior cerebellar peduncle in the rat. The dorsal fold of the DAO is depleted of GAD-positive boutons after lesions extending into the lateral vestibular nucleus (Fredette and Mugnaini, 1991). Additional destruction of the vestibular nuclei results in the disappearance of GAD from the group beta but not from the medial half of the ventral fold of the DAO and the caudal MAO (Nelson and Mugnaini, 

GAD-immunoreactive neurons in the parasolitary and cuneate nuclei could be labelled after injection of retrograde tracers in the inferior olive of the rat (Nelson and Mugnaini, 1989). These nuclei, therefore, provide additional GABAergic projections to the inferior olive. The projection of the ipsilateral parasolitary nucleus was located in the medial subnucleus c of the caudal MAO by these authors. Connections from the parasolitary nucleus (indicated as the lateral solitary nucleus) also were documented in earlier studies by Loewy and Burton (1978) and Molinari (1985) in the cat. The inhibitory connections from the cuneate nucleus in the rat are crossed and terminate in the medial DAO. A similar GABAergic cuneo-olivary pathway appears to be responsible 

The topography in the cerebellar nucleo-olivary projection has been studied in different mammalian species. The nucleo-olivary fibers from the interposed and lateral nuclei run in a separate tract, ventral to the brachium conjunctivum in cat (Legendre and Courville, 1987), rat (Cholley et al., 1989) and rabbit (Tan et al., 1995b). Fastigio-olivary 

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