Reticulocerebellar projections to the anterior and posterior lobes of the rat cerebellum (original) (raw)
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European Journal of Neuroscience, 1996
The projections of the lateral reticular nucleus (LRN) to the cerebellar nuclei were studied using the retrograde axonal transport of tetramethyl rhodamine dextran amine (10% solution in 0.01 M neutral phosphate buffer) in 19 adult Wistar strain rats. The cerebellar nuclei receive topographically organized projections from the LRN. The projections are bilateral with an ipsilateral predominance and they are symmetrical. The contralateral component is progressively larger for projections to the nuclei interpositalis, to the nucleus lateralis and to the nucleus medialis. The projections to the various cerebellar nuclei arise from rostrocaudally oriented columns of neurons located in different (partly overlapping) areas of the magnocellular division of the LRN. The nucleus lateralis receives terminals from the dorsomedial area (mainly from the rostra1 level of the LRN), the nuclei interpositalis from the dorsolateral area (mainly from the central level) and the nucleus medialis from the intermedioventral area (mainly from the caudal level). Afferent fibres from the small subtrigeminal division were traced to the three cerebellar nuclei and from the parvocellular division to the nuclei interpositalis and medialis. The density of the projections from the LRN to the nuclei interpositalis increases progressively with the shift of the terminal field from the rostrolateral to the caudomedial part of the nucleus. The projections to the nucleus lateralis reach principally the dorsolateral hump, whereas only a few neurons project to the other divisions (parvo-and magnocellular). The projections to the various regions of the nucleus medialis show different densities. The highest density was found for projections to the caudal part, in particular to the dorsolateral protuberance and to the ventrolateral area of the middle division. Conversely, a low density of projections was found for the other areas of the middle division. The regions of the magnocellular division of the LRN which project to the nuclei lateralis (and are thus related to the cerebral cortex), interpositalis (related to the red nucleus) and medialis (related to the spinal cord) also receive afferent terminals from the cerebral cortex, the red nucleus and the spinal cord respectively, in addition to various afferent inputs. Thus, each of these areas is apparently concerned with integrating some spinal and supraspinal information in reverberating circuits.
European Journal of Neuroscience, 2002
Compartmentalization (alternating labelled and unlabelled stripes) of mossy fibre terminals was found in the cerebellar cortex after iontophoretic injections of biotinylated dextran amine into discrete regions of the nucleus reticularis tegmenti pontis (NRTP). The zonal pattern was only observed when volumes of nuclear tissue ranging from 4.5 × 106 to 17.66 × 106 µm3 were impregnated. Up to nine compartments (i.e. up to five stripes separated by four interstripes) were found in crus I and in vermal lobule VI. Up to seven compartments (four stripes and three interstripes) were found in crus II; up to five compartments (three stripes and two interstripes) were identified in the lobulus simplex, the paraflocculus and vermal lobules IV, V and VII; up to three compartments (two stripes and one interstripe) were identified in the paramedian lobule and, finally, up to two compartments (one stripe and one interstripe) were identified in the copula pyramidis, in the flocculus and in vermal l...
The Journal of Comparative Neurology, 2002
AB ST R ACT T his stu dy show ed the precise projection pattern of the basilar pontine nu clei (B PN) and the nu cleu s reticu laris tegmenti pontis (NR T P) to the cerebellar nu clei (CN), as w ell as the different anatomic featu res of B PN and NR T P projections. T he staining of B PN or NR T P w ith biotinylated dextran labeled projection fibers to complementary topographic areas in the CN. In fact, B PN principally project to a rostrocau dally oriented colu mn of the nu cleu s lateralis (NL ), w hich at the midcentral lev el shifts to the laterov entral part of the nu cleu s, as w ell as to the cau dolateral part of the nu cleu s interpositu s posterioris. T he NR T P projects to a rostrocau dal colu mn of the NL , w hich at the midcentral lev el shifts medially, as w ell as to the nu cleu s interpositalis and to the cau dal part of the nu cleu s medialis. B PN axons in the CN u su ally branch into short collaterals of simple morphology that inv olv e small terminal areas, w hereas NR T P axons branch into longer collaterals of complex morphology inv olv ing terminal areas of different sizes. E ach site of injection is at the origin of a set of terminal areas in the CN. T he set of projections from different B PN or NR T P areas w ere partially, bu t nev er completely, ov erlapping. T hu s, the set of terminal areas in the CN w as specific for each area of both B PN and NR T P. Injection of tetramethyl-rhodamine-dextran-amine into the CN stained cell bodies of B PN and NR T P w ith different repartition on the tw o sides. T he stu dy show ed that CN are innerv ated by the contralateral B PN and not v ery mu ch by the ipsilateral B PN, w hereas they are innerv ated by NR T P bilaterally, ev en if w ith a contralateral prev alence. In conclu sion, this stu dy su pports the hypothesis that both B PN and NR T P are concerned in the central program for sk illed mov ements, ev en if they are probably inv olv ed in different fu nctional roles. I ndex ing terms: cerebellum; BPN; NRTP; neuroanatomy ; rat T he cerebellu m (CB L ) is reached by mossy fibers from v ariou s brain regions, principally from the basilar pontine nu clei (B PN) and the nu cleu s reticu lar tegmenti pontis (NR T P). T he NR T P w as long considered together w ith the B PN. Inv estigations hav e show n that the NR T P is a specialized nu cleu s of the pontine reticu lar formation (Newman and G insberg, 1992) and that it differs both in ontogeny and in the afferent connectiv ity pattern from the B PN. In fact, w ithin the cortical limits, most afferents to the B PN of rat arise from the entire ipsilateral cortex (L egg et al., 198 9) and principally from sensory (particu larly v isu al and au ditory) and associativ e cortical areas (B rodal and B jaalie, 1992; cf. also Paxinos, 1995, p. 27 8 ), w hereas afferent inpu ts to the NR T P stem from the cingu lar (T origoe et al., 198 6) and, in particu lar, the motor cortices (B rodal, 198 0). L ik e the tegmentu m, how ev er, the NR T P appears to receiv e bilat-eral cortical inpu ts (B rodal, 198 0; L eichnetz et al., 198 4 ) rather than the predominantly ipsilateral inpu ts of the basilar pons . M oreov er, the cortical afferent inpu ts to the NR T P do not generally occu r in the separate w ell-restricted grou ps that are so conspicu ou s in the pontine nu clei in the same sections (B rodal, 198 0). B ecau se the NR T P and B PN differ in ontogenesis and in G rant sponsor: M inistry of E du cation and Scientific R esearch (M U R ST ). * Correspondence to: Federico Cicirata, Dipartimento di Scienze Fisiologiche, V iale A. Doria 6, © 20 0 2 W I LEY-LI S S , I NC.
Anatomy and Embryology, 1982
The projection from the lateral reticular nucleus (LRN) to the cerebellar cortex was studied in the rat by utilizing the retrograde transport of horseradish peroxidase (HRP). In order to study the topographic features of this projection, small amounts of HRP were injected into various sites in the cerebellar cortex. The results demonstrated that the caudal lobules of the anterior lobe vermis tend to receive afferents from the medial LRN and the rostral lobules of the vermis receive afferents from more laterally situated cells. Lobules IV and V receive inputs primarily from the magnocellular division of the LRN of both the ventromedial and dorsolateral parts of the LRN, while lobules II and III receive inputs mainly from cells which lie in the border area between the parvocellular and magnocellular division of the ventromedial part. Following injections within various areas of the posterior lobe vermis, the results indicated that lobule VIII receives the most abundant projection from the LRN and that the cells of origin are present within the parvocellular and the adjacent part of the magnocellular division throughout the rostrocaudal extent of the LRN. Following injections within lobules VI and VII, few labelled cells were found and they tended to lie within the rostral two-thirds of the magnocellular division. Little or no projection from the LRN to lobule IX was evident. The hemispheres were found to receive a modest projection from the dorsal aspect of the LRN. The projection to lobulus simplex originates mainly from the caudal two-thirds of the magnocellular division, while the projection to the ansiform and paramedian lobules originates mainly from the dorsal aspect of the rostral two-thirds of the magnocellular division. Finally, there appears to be extensive overlapping of the origins of all three projections to the cerebellar cortex studied, and this occurs within the central area of the magnocellular division throughout the rostrocaudal extent of the LRN.
The European journal of neuroscience, 2014
Axon collateral projections to various lobules of the cerebellar cortex are thought to contribute to the coordination of neuronal activities among different parts of the cerebellum. Even though lobules I/II and IX/X of the cerebellar vermis are located at the opposite poles in the anterior-posterior axis, they have been shown to receive dense vestibular mossy fiber projections. For climbing fibers, there is also a mirror-image-like organisation in their axonal collaterals between the anterior and posterior cerebellar cortex. However, the detailed organisation of mossy and climbing fiber collateral afferents to lobules I/II and IX/X is still unclear. Here, we carried out a double-labeling study with two retrograde tracers (FluoroGold and MicroRuby) in lobules I/II and IX/X. We examined labeled cells in the vestibular nuclei and inferior olive. We found a low percentage of double-labeled neurons in the vestibular nuclei (2.1 ± 0.9% of tracer-labeled neurons in this brain region), and ...
Multiple zonal projections of the basilar pontine nuclei to the cerebellar cortex of the rat
Journal of comparative neurology, 2001
This study revealed a sagittal zonal pattern of projections to the cerebellar cortex after hydraulic or iontophoretic injections of anterograde tracers (tritiated leucine, wheat germ agglutinin-horseradish peroxidase, or biotinylated dextrane amine) in the basilar pontine nuclei of Wistar rats. The zonal pattern of projection was observed only after injections of small size, whereas large injections labeled diffusely wide areas of the cerebellar cortex, masking the zonal projection because the fusion of contiguous stripes. Diverging projections to discrete sets of sagittal stripes in the two sides of the cerebellar cortex arose from single injections. The stripes of fiber terminals were sharply delimited on both sides by areas, interstripes, either virtually void of labeling or with a much lower density of labeling. Thus, the areas of the cerebellar cortex were parceled in sets of sagittal compartments, stripes and interstripes, by the pontine projections. Up to five compartments (three stripes and two interstripes) were observed in the paraflocculus, in the copula pyramidis, and in vermal lobule IX. Up to nine compartments (five stripes and four interstripes) were found in the crus I, the lobulus simplex, the paramedian lobule, and vermal lobules VI-VIII. Up to seven compartments (four stripes and three interstripes) were found in the crus II. Single injections into the basilar pontine nuclei usually labeled symmetric areas of the cerebellar cortex, which, in some cases, showed similar number of stripes. When this was not the case, the stripes were usually more numerous in the contralateral than in the ipsilateral side. All areas of the cerebellar cortex were projected upon, with zonation patterns from different regions of the basilar pontine nuclei. The projections of the basilar pontine nuclei to the cerebellar cortex were arranged according to a fixed pattern specific for each cortical area, independently of the number of stripes labeled within. The mean width of the stripes visualized in the single cortical areas of different rats was similar, despite the different size of the injections. The length of the stripes ranged widely in the various areas of different rats. The data collected in this study are consistent with the idea that all the mossy afferents to the cerebellar cortex are arranged with a zonal pattern.
Topography of olivo-cortico-nuclear modules in the intermediate cerebellum of the rat
The Journal of Comparative Neurology, 2005
This study provides a detailed anatomical description of the relation between olivocortico-nuclear modules of the intermediate cerebellum of the rat and the intrinsic zebrin pattern of the Purkinje cells. Strips of climbing fibers were labeled using small injections of biotinylated dextran amine into either the medial or dorsal accessory olives, while, in some cases, simultaneous retrograde labeling of Purkinje cells was obtained using gold-lectin injections into selected parts of the interposed nuclei. Our data are represented in a new, highly detailed, cortical surface reconstruction of the zebrin pattern and in relation to the collateral labeling of the climbing fibers to the cerebellar nuclei. We show that the somatotopic regions of the dorsal accessory olive behave differently in their projections to essentially zebrin-negative regions that represent the C1 and C3 zones of the anterior and posterior parts of the cortex. The rostral part of the medial accessory olive projects to zebrin-positive areas, in particular to the P4ϩ band of the anterior lobe and lobule VI and to the P5ϩ band of the posterior lobe, indicating that C2 has two noncontiguous representations in the SL and crus 1. By relating the areas of overlap that resulted from the injections in the accessory olives, i.e., labeling of climbing fiber strips and patches of climbing fiber nuclear collaterals, with the results from the injections in the interposed nuclei, i.e., retrograde labeling of Purkinje cells and of inferior olivary neurons, direct verification of the concept of modular cerebellar connections was obtained.
Topographic organization of the cerebellothalamic projections in the rat. An autoradiographic study
Neuroscience, 1985
The topographical organization of the subnuclear projections towards the thalamus was studied with autographic methods in adult Wistar rats. The four cerebellar deep nuclei give rise to projections to the ventral region of the rostra1 thalamus. Most of the fibers end contralaterally, according to a topographical pattern; however, some fibers from each of the cerebellar nuclei recross the midline at the thalamic level and terminate ipsilaterally, within regions symmetric to those receiving the densest contralateral projection. These ipsilateral cerebellothalamic components arise in decreasing order from the caudal nucleus lateralis, the ventrocaudal nucleus medialis and the nucleus interpositus, respectively. The projections of the nucleus lateralis directed to the contralateral thalamus are topographically organized. (I) Within the nucleus ventralis lateralis, the rostra1 and caudal parts of the cerebellar nucleus lateralis project respectively to rostra1 and caudal regions; lateral and medial zones of the nucleus lateralis project. respectively, to medial and central aspects of the nucleus ventralis lateralis. The nucleus ventralis medialis and particularly its caudal portion appears to receive the bulk of its afferents from the ventromedial portion of the nucleus lateralis including the "subnucleus lateralis parvocellularis". The nucleus centralis lateralis receives fibers from most parts of the nucleus lateralis including the "dorsolateral hump". (4) The nucleus interpositus anterior projects to the dorsomedial aspect of the rostra1 nucleus ventralis lateralis. In the latter nucleus, the ventrolateral aspect of the central region receives projections in cases in which the nucleus interpositus posterior is largely involved.
Journal of Comparative Neurology, 1999
Projection of neurons in the lateral reticular nucleus (LRN) to the cerebellar cortex (Cx) and the deep cerebellar nuclei (DCN) was studied in the rat by using the anterograde tracer biotinylated dextran amine (BDA). After injection of BDA into the LRN, labeled terminals were seen bilaterally in most cases in the vermis, intermediate zone, and hemisphere of the anterior lobe, and in various areas in the posterior lobe, except the flocculus, paraflocculus, and nodulus. Areas of dense terminal projection were often organized in multiple longitudinal zones. The entire axonal trajectory of single axons of labeled LRN neurons was reconstructed from serial sections. Stem axons entered the cerebellum through the inferior cerebellar peduncle (mostly ipsilateral), and ran transversely in the deep cerebellar white matter. They often entered the contralateral side across the midline. Along the way, primary collaterals were successively given off from the transversely running stem axons at almost right angles to the Cx and DCN, and individual primary collaterals had longitudinal arborizations that terminated as mossy fibers in multiple lobules of the Cx. These collaterals arising from single LRN axons terminated bilaterally or unilaterally in the vermis, intermediate area, and sometimes hemisphere, and in different cerebellar and vestibular nuclei simultaneously. The cortical terminals of single axons appeared to be distributed in multiple longitudinal zones that were arranged in a mediolateral direction. All of the LRN axons examined (n ϭ 29) had axon collaterals to the DCN. All of the terminals observed in the DCN and vestibular nuclei belonged to axon collaterals of mossy fibers terminating in the Cx.