The cerebellar nuclei

The parallel fibers receive input from many sources via a complex series of mossy fibers and granule cells and influence the firing of the Punkinje cells. The output from the Purkinje cells is entirely inhibitory. It is transmitted via synapses in the cerebellar nuclei to neurons that lead back to the cerebral cortex, into the thalamus, and down the spinal cord.411 The pathway to the cortex completes an inhibitory feedback loop, of which there are many in the nervous system. For details see Llinas404 and Nicholls.149... 

Fig. 5. Drawing of the brainstem depicting neurons and pathways likely to use glutamate as a neurotransmitter. 1 = primary afferent inputs to the dorsal column nuclei (a), the solitary tract nucleus (b), and the cochlear nucleus (c) 2 = granule cell/parallel fibers in the dorsal cochlear nucleus 3 = calyces of Held in the medial nucleus of the trapezoid body 4 = cochlear nucleus inputs to the lateral superior olive 5 = input to the oculomotor nucleus from the ventral lateral vestibular nucleus 6 = input to the oculomotor nucleus from the abducens nucleus 7 = corticocollieular inputs 8 = spinal input to the periaqueductal gray 9 = inputs to the red nucleus and pontine nuclei from the cerebellar nuclei. For further details, see Section 3.3.

Similar to other projections from the cerebellar nuclei (except those to the inferior olive which are GABAergic), terminals of cerebellar origin in the red nucleus are enriched in Glu (Schwarz and Schmitz, 1997 Fig. 5). Enrichment of Glu has also been detected in terminals in the oculomotor nucleus originating from the abducens and ventral lateral vestibular nuclei (Nguyen and Spencer, 1999 Fig. 5). 

The cerebellar nuclei express mainly the NRl, NR2A and NR2D subunit genes (Watanabe et al., 1994). The NR3A gene is expressed at low levels in the adult cerebellum (cell types unknown) by RT-PCR, the NR3-L splice version predominates (Sun et al., 1998). 

Cerebellar abnormalities may result in disturbances in a neural network involved in the motivation and organization of emotion. Abnormalities in the cerebellar nuclei may play a role in the affective disturbance, abnormal language development, and inappropriate social and psychological behaviors in autism. 

Calmodulin-immunoreactivity was observed both in Purkinje cells and in cells of the cerebellar nuclei of the rat (Lin et al., 1980 Means and Dedman, 1980 Seto-Oshima et al., 1983, 1984). During postnatal development calmodulin-immunoreactivity was transiently present in the inner part of the external germinative layer and in fibers in the white matter of P3-P11 rat pups (Seto-Oshima et al., 1984). 

Nerve growth factor-like immunoreactivity was present in Purkinje cell somata and dendrites, with dense labelling in the paraflocculus, and in neurons of the cerebellar nuclei and the lateral vestibular nucleus of rat cerebellum (Nishio et ah, 1994). All but a few of the Purkinje cells of the adult rat cerebellum stain with an antiserum against basic fibroblast growth factor. Staining was observed in all cellular compartments (Matsuda et ah, 1992). 

Ojima et al. (1989) showed that all cerebellar nuclei in rat are innervated by ChAT-immunoreactive fibers. The density of these fibers varies between the different nuclei. Moderately dense innervation was found in most of the medial nucleus and in the magnocellular part of the lateral nucleus, whereas only a few ChAT-immunoreactive fibers invade the ventromedial parvicellular portion of the lateral nucleus and most of the interposed. Also in the cerebellar nuclei of man a moderate density of ChAT-positive fibers has been observed (DeLacalle et al., 1993). Both in rat and man these fibers did not form pericellular networks. DeLacalle et al. (1993) and Ikeda et al. (1991) also found... 

Ikeda et al. (1991) and DeLacalle et al. (1993) found ChAT immunoreactive neurons in the cerebellar nuclei in cat and man, respectively. According to Ikeda et al. (1991) cholinergic neurons in the cerebellar nuclei project to the cerebellar cortex in the form of mossy fibers, and to the thalamus and the red nucleus (see Section 5.2.). 

The subdivision of the cerebellar nuclei is closely related to the longitudinal, zonal... 

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