Caudal Vermis Research Articles

Immunohistochemical demonstration of expression of tyrosine hydroxylase in cerebellar Purkinje cells of the human and mouse

We demonstrated the expression of tyrosine hydroxylase (TH) and phenylethanolamine- N-methyltransferase (PNMT) in cerebellar Purkinje cells of human and mouse brains by immunohistochemistry. At the age of 8 months, vermal Purkinje cells in the human cerebellum were immunoreactive with anti-TH or anti-human specific PNMT antiserum. We also found TH-positive Purkinje cells in the mouse brain. TH immunoreactivity first appeared in the Purkinje cells in the caudal vermis from postnatal day 8 (P8), and enlarged numbers between P13 and P15. After gradual reduction to P19, the TH-positive Purkinje cells again multiplied the number from the age of 4 weeks, and maintained in a large number up to old stage. At the age of 11 months, the other groups of TH-positive Purkinje cells appeared in the flocculus and paraflocculus of the mouse cerebellum.

Expression of tyrosine hydroxylase in cerebellar Purkinje neurons of the mutant tottering and leaner mouse

In situ hybridization histochemistry, Northern blot analysis and immunohistochemistry were used to examine tyrosine hydroxylase (TH) mRNA concentrations and immunoreactivity in the locus coeruleus and cerebellum of the tottering (tg/tg), leaner (tg la/tg la), compound heterozygous (tg/tg la) and wild type control (+/+) mice, bred on a C57BL/6J background. Cerebellar Purkinje neurons, long considered to be GABAergic, showed high levels of TH mRNA in the caudal vermis and the lateral hemispheres of the cerebellum of tg/tg, tg/tg la, and tg la/tg la mice. Analysis of grain density over individual Purkinje cells showed significantly greater concentrations of TH mRNA in tg/tg, tg/tg la, and tg la/tg la mice as compared to +/+ wild type control mice. Comparison of adult (≥ 2 months) and young, pre-seizure (≤ 3 weeks) mutant mice showed Purkinje cells densely labelled for TH mRNA at both ages, suggesting that TH gene expression in Purkinje cells is independent of the onset of seizures. Northern blot analysis confirmed the findings from the in situ hybridization studies, demonstrating a single band identical to TH mRNA. Immunohistochemistry confirmed the presence of TH protein in Purkinje cells of the caudal vermis and the lateral hemispheres of the cerebellum in both control and mutant mice. Quantitation of mRNA for TH and the coexisting neuropeptide, galanin, in the locus coeruleus detected no significant differences between adult tg/tg, tg/tg la and +/+ control mice. The present findings demonstrate that the classically GABAergic Purkinje cells in the cerebellum express low levels of TH, and that the mutant tottering and leaner strains of mice express extremely high levels of mRNA and protein for TH.

Development of the olivocerebellar projection in the rat: II. Matching of the developmental compartmentations of the cerebellum and inferior olive through the projection map.

A transient biochemical parcellation has been observed by immunocytochemical methods, during the perinatal development of both the inferior olive and the cerebellum. In the present study, we sought a relationship between this developmental compartmentation and the organization of the olivocerebellar projection. In the inferior olive, a transient parvalbumin immunoreactivity restricted to the dorsal cap of the medial accessory olive is observed around birth. The climbing fiber projection of the dorsal cap was identified in the cerebellum of newborn rats based on its parvalbumin immunoreactivity. The pattern of this projection, restricted to lobules IX and X of the vermis, and to the flocculus, is indistinguishable from that of the adult medial accessory olive, which was previously described from axonal tracing experiments. The parvalbumin immunoreactive climbing fibers were followed between birth and postnatal day 7. In the caudal vermis, Purkinje cell subpopulations can be identified between embryonic day 20 and postnatal day three, on the basis of their differential immunostaining with an antibody directed against a specific peptide, PEP 19. In lobule X, the parvalbumin immunoreactive climbing fibers form two sagittal bands on each side of the midline, one medial and one lateral. The medial parvalbumin immunoreactive climbing fiber band is coextensive with a PEP 19 negative Purkinje cell cluster, indicating a clear relationship between the biochemical parcellations of the cerebellum and inferior olive.

Laterality in the vestibulo-cerebellar mossy fiber projection to flocculus and caudal vermis in the rabbit: A retrograde fluorescent double-labeling study

The vestibular nuclear input into the flocculus and the uvula and nodulus of the caudal vermis was studied in rabbits by means of retrograde transport of the fluorescent tracers Fast Blue and Diamidino Yellow. Through simultaneous injection of the tracers in the homonymous lobules at either side of the midline, the distribution, the preference in laterality and the degree of collateralization of vestibulocerebellar neurons could be studied. The nucleus prepositus hypoglossi was included in the analysis. In the nucleus prepositus hypoglossi and in the medial vestibular nucleus 6% of the number of labeled neurons contained both tracers, against 4% in the descending vestibular nucleus. In the superior vestibular nucleus a statistically significant difference in the proportion of double-labeled neurons was found between cases with injections in the flocculus (1%) and the caudal vermis (9%). The relative distribution of single-labeled neurons projecting to either the flocculus or the caudal vermis was similar in most of the vestibular nuclei. A statistically significant preference for a projection to the flocculus in favor of one to the caudal vermis, was found for neurons in the medial vestibular nucleus and the prepositus hypoglossal nucleus. Statistically significant laterality preferences were found in the superior vestibular nucleus for the contralateral flocculus.

Secondary vestibulocerebellar projections to the flocculus and uvulo-nodular lobule of the rabbit: a study using HRP and double fluorescent tracer techniques

The distribution of vestibular neurons projecting to the flocculus and the nodulus and uvula of the caudal vermis (Larsell's lobules X and IX) was investigated with retrograde axonal transport of horseradish peroxidase and the fluorescent tracers Fast Blue, Nuclear Yellow and Diamindino Yellow. The presence of collateral axons innervating the flocculus on one hand and the nodulus and uvula on the other was studied with simultaneous injection of the different fluorescent racers. The distribution of vestibular neurons projecting to either flocculus or caudal vermis is rather similar and has a bilateral symmetry. The projection from the magnocellular medial vestibular nucleus is very sparse, while that from the lateral vestibular nucleus is absent. The majority of labeled neurons was found in the medial, superior, and descending vestibular nuclei, in that order. Double labeled neurons were distributed in a similar way as the single labeled ones. Labeled neurons project to the nodulus and uvula, the flocculus, and to both parts of the cerebellum simultaneously in a ratio of 12:4:1. Five different populations of vestibulocerebellar neurons can be distinguished on the basis of their projection to the: (1) ipsilateral flocculus, (2) contralateral flocculus, (3) ipsilateral flocculus and nodulus/uvula, (4) contralateral flocculus and nodulus/uvula, and (5) nodulus/uvula.

Secondary vestibulocerebellar mossy fiber projection to the caudal vermis in the rabbit

The vestibulocerebellar projection in the rabbit has been investigated by the anterograde axonal transport of tritiated leucine, wheat germ-agglutinated horseradish peroxidase, and Phaseolus vulgaris leucoagglutinin. Mossy fiber terminals originating from all vestibular nuclei, with the exception of the lateral vestibular nucleus of Deiters, were found bilaterally in the lobules X, IX, and VIII of the caudal vermis, without a clear difference in laterality. Most of the vestibular mossy fiber terminals in the caudal vermis originated in the superior and caudal medial vestibular nuclei. Application of the different tracers led to similar results. The labeled terminals were always most numerous in the lobules X and IXd. Small to moderate numbers of mossy fiber terminals were found in the lobules IXa, b, c, and lobule VIII. The greatest change in the density of terminals occurred in most cases around the apex of lobule IXd and not in the depth of the posterolateral fissure between lobules X and IX. The mossy fiber terminals were not distributed equally over the cortex but showed a preference for the proximal parts of the individual lobules. In all experiments, the terminals exhibited a certain degree of clustering in the mediolateral direction, but the clusters were not arranged in longitudinal zones continuous over successive folia.

Anatomical connections of the prepositus and abducens nuclei in the squirrel monkey.

The primary goal of this investigation was to identify the areas of the brainstem and cerebellum that provide afferent projections to the nucleus prepositus hypoglossi in primates. After horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) was injected into the prepositus in squirrel monkeys (Saimiri sciureus), the largest populations of retrogradely labeled neurons were found in the vestibular nuclei, the contralateral perihypoglossal nuclei, and the medullary and pontine reticular formation. Unlike the cat, the prepositus in Saimiri received substantial projections from the nucleus raphe dorsalis and the central mesencephalic reticular formation, whereas few or no labeled cells were found in the cerebellar cortex, the superior colliculus, or the nucleus reticularis tegmenti pontis. By comparing the afferents to the prepositus with those to the abducens nucleus, we found that all regions projecting to the abducens also projected to the prepositus, without exception. Anterogradely transported WGA-HRP showed that the major brainstem recipients of prepositus efferents were the vestibular and perihypoglossal nuclei, the inferior olive, the medullary reticular formation, and the extraocular motor nuclei. In the cerebellar cortex, the prepositus projected to restricted regions of crura I and II as well as the caudal vermis and vestibulocerebellum. The many parts of the oculomotor system receiving input from the prepositus and the parallel innervation of the prepositus and the abducens by a large number of premotor centers lend support to the hypothesis that the prepositus may distribute an efference copy of motor activity, and may also play an important role in the process of neural integration.

Somatosensory projections of cerebellar granule cell layer of giant bushbaby, Galago crassicaudatus.

Recent neurophysiological studies of the granule cell (GC) layer in opossums and rats revealed extensive somatosensory projections to the cerebellar hemispheres and caudal vermis. These projections are organized as asomatotopic mosaics that are species-specific. To determine whether similar projections exist in a primate with a relatively small and simple cerebellum, we explored the GC layer of exposed folial crowns of anterior and posterior lobe cerebellar cortex of anesthetized giant galagos using juxtathreshold natural stimulation of mechanoreceptors and in-depth microelectrode micromapping techniques. We found (1) that stimulation of somatosensory mechanoreceptors by gentle touch, deep pressure, muscle stretch and joint movement revealed projections to the GC layer throughout the mediolateral extent of crus II, paramedian lobule, pyramis and rostral uvula (crus I was unresponsive); (2) that mosaic patterns of peripheral sources and submodality of projections were different for each lobule, and (3) that there were intraspecies and individual differences in subfoliation and in details of projections. Except for differences in mosaic pattern and relative size of different projections, these findings are similar to those in opossums and rats. These data suggest that somatosensory inputs to the cerebellum are not only functionally significant, but that they exist widely among mammals.

Regular stripe-like activation and suppression of metabolic activity in the cerebellar cortex following apomorphine administration to haloperidol-pretreated rats

Alteration of the pattern of metabolic activity in the cerebellar cortex, as produced by apomorphine in rats given chronic pretreatment with haloperidol was studied by means of the [ 14 C]deoxyglucose method. Apomorphine induced a regular stripe-like activation and suppression of metabolic activity in the caudal paravermal area of the cerebellar hemisphere and in the caudal vermis of the cerebellar cortex. This stripe-like pattern, oriented perpendicularly to the cerebellar fissure, suggests the functional organization of the cerebellar cortex in a direction which is parallel to the longitudinal axis of folia.

Regular stripe-like activation and suppression of metabolic activity in the cerebellar cortex following apomorphine administration to haloperidol-pretreated rats

Alteration of the pattern of metabolic activity in the cerebellar cortex, as produced by apomorphine in rats given chronic pretreatment with haloperidol was studied by means of the [ 14C]deoxyglucose method. Apomorphine induced a regular stripe-like activation and suppression of metabolic activity in the caudal paravermal area of the cerebellar hemisphere and in the caudal vermis of the cerebellar cortex. This stripe-like pattern, oriented perpendicularly to the cerebellar fissure, suggests the functional organization of the cerebellar cortex in a direction which is parallel to the longitudinal axis of folia.

Correlation of clinical signs with CT findings in patients with cerebellar disease.

The severity of cerebellar signs and the degree of cerebellar atrophy depicted by computed tomography (CT) were independently graded in 108 patients with cerebellar disorders. The overall agreement between these independently scaled measures was only 28%. In patients with involvement of the cerebellar hemispheres and anterior lobe, clinical signs tended to be more pronounced than the cerebellar atrophy revealed by CT. The opposite was true for patients with lesions of the caudal vermis. Patients with Friedreich's ataxia had no or only minor CT abnormalities. Close correlation between the degree of infra- and supratentorial atrophy was found only in chronic alcoholics. The poor correlation between changes in cerebellar structure detected by CT and clinical disability suggests the need for caution in CT interpretation.

Cerebellar corticonuclear and corticovestibular fibers from the posterior lobe of the albino rat, with comments on zones.

The topographic organization of cerebellar cortical efferent fibers from the posterior lobe of the albino rat was studied by silver impregnation methods. The corticonuclear fibers from the vermis of the posterior lobe project to the caudomedial and middle parts of the medial cerebellar nucleus (MN) with medio-lateral localization; fibers from the medial portion of the vermis project to the caudomedial part of the MN (MNcm) and those from the lateral portion project to the middle part of the MN (MNm). Corticovestibular fibers originate in the caudal vermis lateral to the area projecting to the MNcm and MNm, and terminate in the dorsal part of the lateral vestibular nucleus (LVN). The origins of corticonuclear fibers to the dorsolateral protuberance of the MN (MNdlp), the posterior interpositus nucleus (PIN) and the anterior interpositus nucleus (AIN) are located latero-medially in the intermediate cortex. Fibers from the area adjacent to the vermis and rostral to the prepyramidal fissure project to the MNdlp, while those from the area lateral to the origin of the corticovestibular fibers and caudal to the fissure project to the medial AIN. Together, these areas comprise a medial portion of the intermediate cortex. Corticonuclear fibers to the PIN and lateral AIN originate from the lateral portion of the intermediate cortex. The corticonuclear fibers to the dorsolateral hump and lateral nucleus originate from the medial and lateral portions of the lateral cortex, respectively.

Reciprocal connections between the caudal vermis and the vestibular nuclei in the rabbit

The termination of secondary vestibulocerebellar mossy fibers and the localization of Purkinje cells giving rise to corticovestibular projections were visualized simultaneously in lobules IX and X after injections of wheat germ agglutinin-horseradish peroxidase in the vestibular nuclei of the rabbit. Vestibulocerebellar mossy fibers from the medial, descending and superior vestibular nuclei terminate in longitudinal strips in the granular layer, which coincide exactly with the localization of the labeled Purkinje cells.

Tactile Cutaneous Representation in Cerebellar Granule Cell Layer of the Opossum, <i>Didelphis virginiana</i> (Part 2 of 2)

Recent studies of the albino rat revealed extensive cutaneous somatosensory projections to the granule cell (GC) layer of the cerebellar hemispheres and the caudal vermis. These projections are organized asomatotopically in patchy mosaics. To determine whether similar projections exist in a marsupial, we explored the GC layer of the cerebellar cortex of anesthetized Virginia opossums using in-depth microelectrode micromapping and juxtathreshold cutaneous natural stimulation techniques.We found: (1) Somatosensory projections to the GC layer exist throughout the medio-lateral extent of the folia of the posterior lobe. The anterior lobe was not explored. (2) The submodality of most receptive fields was 'gentle-touch' cutaneous, but some were located in muscle, joint, or other deep-lying structures. (3) Peripheral projections to the GC layer are organized asomatotopically. (4) Adjacent body parts project disjunctively to nonadjacent GC regions, and the overall pattern of peripheral projections forms a patchy columnar mosaic. (5) Many body parts send projections to multiple loci. (6) Ipsilateral projections predominate. (7) Mechanoreceptors from face, snout, mouth and teeth activate the bulk of GC loci on crus I and crus II. The paramedian lobule receives projections from the entire ipsilateral body; the pyramis is activated from hindlimb and forelimb; the uvula from the upper arm and vibrissae. (8) Different folia have different combinations and arrangements of disjunctive patchy peripheral projections. (9) Individual differences in pattern of foliation and body representation occur.Except for differences in mosaic pattern and relative size of different projections, these findings are similar to those in rats and cats. These data suggest that somatosensory (especially cutaneous) inputs to the cerebellum are not only functionally significant, but that they exist widely among mammals.

Tactile projections to granule cells in caudal vermis of the rat's cerebellum.

We discovered a small tactile area in a single a folium of the uvula of the cauday vermis of the rat's cerebellum. Gentle mechanical stimulation of relatively small cutaneous receptive fields (RFs) activated multiple units in the granule cell (GC) layer in a portion of a single folium in rats anesthetized with sodium pentobarbital. The total size of this area on each side of the midline is about 1.5 mm2, yet micromapping within this tiny region using tungsten ball microelectrodes and a high puncture sampling density (about 75 punctures/mm2) revealed a highly differentiated pattern of cutaneous projections to the GC layer. All peripheral projections are ipsilateral; the two homologous areas from each side adjoining at the midline of folium 9a. The larger projection areas from cutaneous RFs are mostly from mystacial vibrissae and upper lip, but small projection sites from the remainder of the head, neck and forelimb also are present. The pattern of projections were patch-like, forming a fractured somatotopic pattern or mosaic, with some somatotopic and some nonsomatotopic features. Each RF activated units in a vertical column in the GC layer. This area has not been described in any mammal, and its functional role can now be studied.

Performance of a motor task after cerebellar cortical lesions in rats

Rats with lesions of the cerebellar cortex of the hemispheres, the lobus medius of the vermis and the caudal vermis were tested on a difficult motor task. Hemisphere lesions produced no significant deficits but lesions of the medial and caudal vermis did. No evidence of recovery was seen in the latter two groups.