Cerebellar nuclei projections

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.). 

Buisseret-Delmas C, Batini C, Compoint C, Daniel H, Menetrey D (1989) The GABAergic neurones of the cerebellar nuclei projection to the caudal inferior olive and to the bulbar reticular formation. Exp. Brain Res. SI7, 108-110. 

Fig. 164. The nucleo-olivary projection in the rat. Data from Ruigrok and Voogd (1990). Upper and lower block diagrams represent the cerebellar and vestibular nuclei, and the subdivisions of the inferior olive respectively. According to Ruigrok and Voogd (1990) the cerebellar nuclei and their olivary target nuclei can be considered as a continuum, stretching from the rostral medial cerebellar nucleus, projecting to caudal MAO, to the lateral vestibular nucleus, projecting to the dorsal fold of the DAO. DL = dorsolateral protuberance of the medial cerebellar nucleus DMC = dorsomedial cell column IntA = anterior interposed nucleus IntDL = dorsolateral hump IntP = posterior interposed nucleus lOD = dorsal accessory olive lODM = dorsomedial cell column lOM = medial accessory olive lOP = principal olive Lat = lateral cerebellar nucleus LVe = lateral vestibular nucleus Med = medial cerebellar nucleus VL = ventrolateral outgrowth.

The (central) cerebellar nuclei and the lateral vestibular nucleus of Deiters receive the axons of the Purkinje cells of the cerebellar cortex and serve as the main output stations of the cerebellum. The vermis and the flocculus also project to other vestibular nuclei, but here the Purkinje cell axons compete with vestibular root fibers, intrinsic and commissural vestibular connections and projections from the medial cerebellar nucleus and, therefore, are not the dominant afferent system. 

The term d, was applied to a narrow strip of climbing fiber-evoked potentials in the extreme lateral part of the anterior lobe by Ekerot and Larson (1979a, see Figs 171 and 175 ). The d2 zone can be activated by the dorsal spino-olivo-cerebellar-climbing-fiber-path and receives branches from climbing fibers which also innervate the lateral c, zone (Ekerot and Larson, 1982). The use of the letter d for this zone is misleading, because it neither projects to the lateral cerebellar nucleus or receives a projection from the principal olive. 

Only few observations in primates are available on the corticonuclear projection of the posterior lobe. Haines and Whitworth (1978) and Haines and Patrick (1981) studied the projection of the paramedian lobule and the paraflocculus in the tree shrew Tupaia glis). They concluded that , 3 and a D zone, with a similar topography and corticonuclear projection as in the cat, were present in the paramedian lobule of the tree shrew. The C2 and the D zone continued into the paraflocculus, where the D zone could be subdivided into D, and Dj zones on the basis of its differential projection to the lateral cerebellar nucleus. The organization of the posterior vermis in primates (Haines, 1975a,b) will be dealt with in the Sections on the vestibular cerebellum (6.1.5.) and the olivocerebellar projection (6.3.3.3.). 

Fig. 128. Diagrammatic representation of the corticonuclear projection of lobule V in Galago. There are at least six identifiable corticonuclear projection zones in the lobule V cortex. The vermis consists of zones A and B, the intermediate cortex of three zones C, - C3 and the lateral cortex of a single D zone, f = flocculus IC = intermediate cortex LC = lateral cortex Ivn = lateral vestibular nucleus 1-nia = lateral anterior interposed nucleus m - nia = medial anterior interposed nucleus m - nip = medial posterior interposed nucleus nl = lateral cerebellar nucleus nm = medial nucleus vc = vermal cortex. Haines and Rubertone (1979)...

The zonal organization of the efferent connections of the caudal vermis in the rabbit is quite complex, with discrete zones in the lobules IX and X projecting to the fastigial, descending, superior and medial vestibular nuclei, and lateral zones connected to the interposed and different subdivisions of the lateral cerebellar nucleus (van Rossum,... 

Fig. 152. Diagrams showing the topographic pattern of the projections from the various mediolateral levels of the tuber vermis (lobule VII) and the paramedian lobule to the cerebellar nuclear complex in the rat. A. Schematic diagram of the posterior surface of the cerebellum and subdivision of the tuber vermis and paramedian lobule, based on the topography of their projections. B. Schematic sagittal diagrams of the nuclear complex showing the terminal fields which receive projections from the individual subdivisions of the tuber vermis and paramedian lobule. AIN = anterior interposed nucleus cm = caudomedial sub-division of the medial nucleus Cop. pyr = copula pyramidis DLH = dorsolateral hump DLP = dorsolateral protuberance of the medial nucleus LN = lateral cerebellar nucleus LVN = lateral vestibular nucleus m = medial nucleus PIN = posterior interposed nucleus Pml = paramedian lobule. Umetani (1989).

Buisseret-Delmas and Angaut (1989b, 1993) defined three D-zones in the lateral part of the anterior lobe on the basis of their corticonuclear projection to the dorsolateral hump (Do), the dorsal magnocellular part of the lateral cerebellar nucleus (D,) and the ventral parvicellular part of this nucleus (Dj). They receive their olivocerebellar projections, respectively, from the DM group and the medial half of the ventral leaf of the PO (Do), the dorsal leaf of the PO (D,) and the lateral half of the ventral leaf of the PO (D2) (see Fig. 141). 

Fig. 204. Diagrams of the distribution of degenerated, silver impregnated spinocerebellar and pontocerebellar fibers after lesions of the cervical cord and the pes pontis with the nucleus reticularis tegmenti pontis in sagittal (upper panels), transverse (middle panels) and horizontal sections (lower panels) through the cerebellum of Tupaia glis. Note zonal distribution in the vermis and pars intermedia and complementarity of the two projections to the cortex and to the cerebellar nuclei illustrated in middle and lower panels. ANS = antiform lobule cr = restiform body fl = primary fissure FLO = flocculus ia = anterior interposed nucleus ip = posterior interposed nucleus L = lateral cerebellar nucleus m = medial cerebellar nucleus PFL = parafloc-culus SI = simple lobule 1-X = lobules I-X. Voogd, unpublished.

The collateral projections from the lateral reticular nucleus terminate in the same regions of the cerebellar nuclei as the direct spinocerebellar projections. According to Matsushita and Ikeda (1976) they are absent from the lateral cerebellar nucleus in the cat, but according to Dietrichs (1983b) certain parts of the lateral nucleus receive lateral reticular afferents. A weak projection of the lateral reticular nucleus to the lateral vestibular nucleus that was described by Dietrichs and Walberg (1979a) in the cat, recently was confirmed in the rat (Ruigrok et al., 1995). 

Collateral projections from the pontine nuclei were mostly traced from the nucleus reticularis tegmenti pontis. Smaller contributions from the dorsolateral and medial pontine nuclei were found by Gerrits and Voogd (1987) in the cat and Mihailoff (1993) in the rat. Their termination is mostly in the lateral part of the posterior interposed nucleus and in the lateral cerebellar nucleus. The caudal pole of the fastigial nucleus receives a projection in cat and Tupaia (Fig.204). It appears as though the collateral... 

Dietrichs E, Walberg F (1985) The cerebellar nucleo-olivary and olivo-cerebellar nuclear projections in the cat as studied with anterograde and retrograde transport in the same animal after implantation of crystalline WGA-HRP. II. The fastigial nucleus. Anat. Embryoi. 173, 253-261. 

Mihailoff GA (1993) Cerebellar nuclear projections from the basilar pontine nuclei and nucleus reticularis tegmenti pontis as demonstrated with PHA-L tracing in the rat. J. Comp. Neurol., 330, 130-146. 

Sato Y, Kawasaki T, Ikatashi K (1982b) Zonal organization of the floccular Purkinje cells projecting to the group X of the vestibular complex and the lateral cerebellar nucleus in cats. Brain Res., 234, 430 34. 

The PFC, PAC, and ITC all project to the caudate nucleus as part of the cognitive circuit through the basal ganglia, which projects via the thalamus back to PFC (Fig. 8.2). In contrast, the motor circuit involves cortical projections to the putamen, which in turn projects back onto the premotor cortices (Fig. 8.2). This pathway is important for the planning, selection, initiation, and execution of movements. The entire cortical mantle also projects indirectly to the cerebellar cortex (not shown), which ultimately projects back to the primary motor cortex. This pathway serves as a biological gyroscope, providing on-line correction of movements. 

Ikai et al. (1992) reported that the VTA sends projections to the rat cerebellar cortex and deep cerebellar nuclei bilaterally, with a slight contralateral predominance. In this study, dopaminergic efferents of the A10 cell group were reported to reach mainly the granule cell layer of the cerebellar cortex in the lateral portion of the hemispheres, with additional input to the Purkinje cell layer, but sparing the molecular layer. The deep cerebellar nuclei, and in particular the lateral nucleus, were instead found to receive inputs from nondopaminergic cells of the VTA, reciprocating projections to the VTA bilaterally and with a contralateral predominance. 

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). 

Schwarz C, Schmitz Y (1997) Projections from the cerebellar lateral nucleus to precerebellar nuclei in the mossy fiber pathway is glutamatergic a. study combining anterograde tracing with immunogold labeling in the rat. J Comp Neurol 3S/ 320-334. 

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