Cerebellar nuclei interposed nucleus

InM intermedius nucleus of the medulla 74 IntA interposed cerebellar nucleus, anterior part 63-66, 82-85,103-106... 

IntDL interposed cerebellar nucleus, dorsolateral hump 65 IntDM interposed cerebellar nucleus, dorsomedial crest 65-66,105 IntP interposed cerebellar nucleus, posterior part 66-67, 82-84,101-105... 

IntPPC interposed cerebellar nucleus, posterior parvicellular part 66 InWh intermediate white layer of the superior colliculus 42-52, 80-84, 105, 107-114 lO inferior olive 79-81... 

The subdivision of Weidenreich-Ogawa received strong support from the localization of the fibers in the superior cerebellar peduncle. A small medial and a large lateral portion can be distinguished in this pathway in most mammals at its exit from the central nuclei (see in Fig. 102). Experiments in cat (Verhaart, 1956 Voogd, 1964) and rat (Haroian et ah, 1981) have shown that the medial part of the superior cerebellar peduncle takes its origin from the nuclei of the caudomedial group, mainly from the ipsilateral posterior interposed nucleus, and the lateral portion from the ipsilateral anterior interposed and lateral cerebellar nucleus. 

Fig. 103. The cerebellar nuclei of the cat. The transitional U-shaped region of the fastigial and posterior interposed nuclei is indicated by double hatching, be = brachium conjunctivum cr = restiform body DV = descending vestibular nucleus F = fastigial nucleus flo = floccular peduncle Ftail = tail of the fastigial nucleus lA = anterior interposed nucleus IP = posterior interposed nucleus L = lateral cerebellar nucleus LV = lateral vestibular nucleus MV = medial vestibular nucleus SV = superior vestibular nucleus u = uncinate tract Y = group y of Brodal and Pompeiano (1957).

Fig. 104. Two transverse, AChE-incubated sections through the cerebellar nuclei of the cat, A. Rostral section. B. Caudal section. Note medium-sized cells of dorsal group y in floccular peduncle and strongly AChE positive ventral group y along dorsal border of restiform body in (A) U-shaped nucleus between IP and F in (B). cr = restiform body F = fastigial nucleus flo-i-y = floccular peduncle with group y lA = anterior interposed nucleus IP = posterior interposed nucleus IP/F = U-shaped nucleus between F and IP L = lateral cerebellar nucleus sad = stria acoustica dorsalis.

The existence of a rest group of neurons that remains unaffected by large lesions of the efferent cerebellar pathways in the kitten has been claimed as evidence in favour of the presence of intrinsic or nucleocortical neurons in the central nuclei (Jansen and Jansen 1955). Many of these neurons were found to be large and to be located in the posterior interposed nucleus. Intrinsic neurons of the cerebellar nuclei have been observed in Golgi preparations of the rat by Chan-Palay (1973a, 1977) as small multipolar neurons in the dentate nucleus. The terminals of these intrinsic, inhibitory neurons on the soma and dendrites of cerebellar nuclear cells were tentatively identified as small... 

Rg. 117. Localization of serotonin-like immunoreactivity in transverse sections through the cerebellar nuclei of the opossum. DN = dentate nucleus FN = fastigial nucleus IPA = anterior interposed nucleus IPP = posterior interposed nucleus. Bishop et al. (1985). 

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)...

Fig. 129. Schematic drawing of the distribution of motilin-immunoreactive (M-i) Purkinje cells (open triangles) and glutamic acid decarboxylase-immunoreactive (GAD-i) Purkinje cells (filled circles) in a coronal section of rat cerebellum. M-i cells and GAD-i cells are both more concentrated in the flocculus and the paraflocculus than elsewhere. Both cell types occur in the vermis and participate in the formation of the sagittal microzones (arrows). M-i terminal axon projections in the deep cerebellar nuclei are heaviest in the dentate (D left side) and GAD-i projections are heaviest in the lateral vestibular nucleus (LV right side). 1 = interposed nucleus F = fastigial nucleus. Chan-Palay et al. (1981).

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. 150. Diagram of the afferent olivocerebellar projection according to Katayama and Nisimaru (1988) and the efferent projection of the zones of the nodulus to the vestibular and cerebellar nuclei according to Wylie et al. (1994) in the rabbit. P = group 8 of the medial accessory olive DC = dorsal cap of Kooy F = fastigial nucleus IP = posterior interposed nucleus MV = medial vestibular nucleus P cell = Purkinje cell SV = superior vestibular nucleus VLO = ventrolateral outgrowth I-VI = zones of rabbit nodulus, numbered according to Katayama and Nisimaru (1988).

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).

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.

Fig. 191. Schematic line drawings of the unfolded opossum cerebellum modified after Larsell and Jansen (1972). The broken lines indicate the boundaries of the corticonuclear zones A-D after Klinkhachorn et al. (1984a). The distribution of the three types of enkephalinergic axons is indicated by the frequency and size of the symbols the beaded axons by asterisks (C), the mossy fibers by dots (A), and the climbing fibers by triangles (B). I-X indicate vermal lobules CR I, II, crura I and II, F, flocculus LS, lobulus simplex PFL, paraflocculus PML, paramedian lobule. D. Distribution of enkephalinergic axons in a horizontal section through the cerebellar nuclei. D, dentate nucleus, F, fastigial nucleus IPA, anterior interposed nucleus IPP, posterior interposed nucleus. From King et al. (1987).

Fig. 194. Three transverse sections through the cerebellum of the cat showing corticotrophin releasing factor (CRF)-like immunoreactivity in climbing fibers in the molecular layer (radial lines) and mossy fibers (dots) in the granular layer. Note corresponding positions (arrows) of strongly labelled climbing fibers and mossy fibers (arrows). Abbreviations CR I, II, Crus I and II FL, flocculus LS, simple lobule NIP, posterior interposed nucleus NL, lateral cerebellar nucleus NM, medial nucleus PFL, paraflocculus PML, paramedian lobule I-X, lobules I-X of Larsell. Cummings (1989).

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.

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... 

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