Inferior Vestibular Nucleus


The highest density of immunoreactive fibers was found in the motor trigeminal nucleus, the laminar and alaminar spinal trigeminal nuclei, the facial nucleus, the marginal nucleus of the brachium conjunctivum, the locus coeruleus, the cuneiform nucleus, the dorsal motor nucleus of the vagus, the postpyramidal nucleus of the raphe, the lateral tegmental field, the Kölliker-Fuse nucleus, the inferior central nucleus, the periaqueductal gray, the nucleus of the solitary tract, and in the inferior vestibular nucleus.  

NOS I-positive neurons and fibres were found in all parts of VNCc: medial vestibular nucleus (MVN); lateral vestibular nucleus (LVN); superior vestibular nucleus (SVN); inferior vestibular nucleus (IVN); X, Y, Z groups and Cajal's nucleus.  

Previous anatomical studies in rabbits and rats have shown that the superior vestibular nucleus (SVN), medial vestibular nucleus (MVN) and inferior vestibular nucleus (IVN) project to the parabrachial nucleus (PBN) and Kölliker-Fuse (KF) nucleus.  

Clusters of L-citrulline-immunoreactive neurons are present in subregions of the vestibular nuclei, including the caudal portion of the inferior vestibular nucleus, the magnocellular portion of the medial vestibular nucleus, and the large cells in the ventral tier of the lateral vestibular nucleus.  

Following selective iontophoretic injections of WGA-HRP into the dCo, a small number of labelled neurones (from 2 to 28 per case) was found in the rostral and caudal portions of the medial vestibular nucleus and in the inferior vestibular nucleus.  

The distribution of retrogradely labeled Purkinje cells revealed that efferent projections from the dorsal surface of the flocculus and the ventral paraflocculus to the superior vestibular nucleus, rostral medial vestibular nucleus, ventral lateral vestibular nucleus, and caudal aspect of the vestibular nuclear complex (caudal medial vestibular nucleus, inferior vestibular nucleus and nucleus prepositus hypoglossi) tended to correspond to previously identified climbing fiber zones [ Ruigrok et al.  

Less dense innervation was observed in the MVN, and minimal innervation was observed in the inferior vestibular nucleus (IVN).  

A moderate density of retrogradely labeled neurons was found in the ipsilateral side of the nuclei parvocellularis, retrorubral (RRN), PoO, and vestibular complex, in the contralateral PoC and nucleus gigantocellularis, and bilaterally in the inferior vestibular nucleus.  

Neuroanatomical studies in the rabbit and in the cat have identified descending vestibulo-autonomic pathways from the caudal portion of the medial vestibular nucleus and the inferior vestibular nucleus to the dorsal motor nucleus of the vagus nerve, the nucleus of the solitary tract, and some brain stem medullary sympathetic regions. Finally, anterogradely labeled ascending fibers were traced from the caudal medial vestibular nucleus and the inferior vestibular nucleus to the medial, lateral, ventrolateral, and Kolliker-Fuse regions of parabrachial nucleus. Similar to findings in the rabbit (Balaban and Beryozkin, 1994), retrogradely labeled cells were observed in the caudal medial vestibular nucleus and the inferior vestibular nucleus.  

With light and electron microscopy, using mice, we studied the central branches of medial olivocochlear neurons that are given off to the inferior vestibular nucleus. These results indicate that the inferior vestibular nucleus is an integrating center for vestibular, auditory, and other types of information, but the results do not fit with current theories about the function of the olivocochlear system..  

From the caudal part of the fastigial nucleus, projections to the cranial motor nuclei (IV, VI and VII), VLV and inferior vestibular nucleus were observed..  

Injections in the caudal dorsal cap, though, labeled neurons bilaterally in the rostral medial vestibular nucleus, predominantly ipsilaterally in pars beta of the lateral vestibular nucleus and almost exclusively ipsilaterally in caudal pars alpha of the lateral vestibular nucleus and the rostral aspect of the inferior vestibular nucleus. Vestibular nucleus injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin indicated (1) that a predominantly ipsilateral projection to the caudal dorsal cap originates bilaterally from the pars beta of the lateral vestibular nucleus and the rostroventral aspect of the rostral medial vestibular nucleus, (2) that the medial half of the caudal medial vestibular nucleus is the source of a predominantly contralateral projection to dorsal cap, (3) that the caudal aspect of nucleus prepositus hypoglossi contributes a predominantly ipsilateral projection to the medial accessory olive and (4) that the rostral aspect of inferior vestibular nucleus and the dorsal and lateral aspects of the caudal medial vestibular nucleus project to nucleus beta of the medial accessory olive.  

Anterogradely labeled axons from the caudal medial vestibular nucleus (cMVN) and inferior vestibular nucleus (IVN) could be traced bilaterally to nucleus tractus solitarius (NTS).  

The superior vestibular nucleus (SV) and the medial vestibular nucleus (MV) receive projections exclusively from RPc and RGc, whereas the lateral reticular nucleus (LV) and the inferior vestibular nucleus (IV) receive additional projections from the remaining RF nuclei.  

Branches from medial olivocochlear fibers terminated in the inferior vestibular nucleus or in the cochlear nuclear complex.  

CYP1A1 and mEH immunoreactivity was present in most neurons of the SN, RN, P, median raphae, locus ceruleus, inferior vestibular nucleus, dorsal motor nucleus of the vagus, and thalamus.  

In the inferior vestibular nucleus (IVe), the vestibulospinal neurons were produced almost equally on both E12 and E13.  

A medial descending noradrenergic bundle provides input to the lateral vestibular nucleus (LVN), medial vestibular nucleus (MVN), and the inferior vestibular nucleus (IVN) before continuing on to the cochlear and cerebellar nuclei.  

Also, there was greater Fos expression in the dorsomedial cell column, the principal inferior olive subnuclei, inferior vestibular nucleus, the dorsolateral central gray, and the locus coeruleus in animals who had their heads restrained compared to animals whose heads were not restrained.  

A double label technique revealed that CGRP-IR mossy fibers arise from neurons located in the lateral reticular nucleus, external cuneate nucleus, inferior vestibular nucleus, and basilar pons.  

The only salient feature was that cells projecting onto zones C2, C1 and C3 of the PML were arranged rostrocaudally in the inferior vestibular nucleus and the caudal portion of the medial vestibular nucleus.  

This study demonstrates that somatostatin (SRIF), an endogenous peptide in vestibular nuclei and cerebellum, can produce both a dose-dependent death of Purkinje cells in distinct sagittal regions of cerebellar cortex and vascular infarcts centered selectively in the inferior vestibular nucleus. These infarcts could be unilateral or bilateral and always involved the inferior vestibular nucleus at the level of the caudal margin of the acoustic tubercle; they often extended into the medial and lateral vestibular nuclei.  

In addition to the previous report that CGRP-LI cells were found in the lateral vestibular nucleus, the present study clarified that they are found also in the inferior vestibular nucleus, medial vestibular nucleus and nucleus X. CGRP-LI cells in the inferior vestibular nucleus are small to medium in size and triangular or pea shaped. CGRP-LI fibers are more extensively distributed in various areas throughout the vestibular nuclei, though previous studies reported that they were found in the lateral vestibular nucleus and inferior vestibular nucleus. A number of CGRP-LI fibers are clearly observed in the inferior vestibular nucleus.  

The descending branch, while running caudally in the lateral part of the LVN and the inferior vestibular nucleus (IVN), gave off several thick collaterals to the MVN and extensive terminals were present in the IVN and MVN.  

En route to the cochlea, the thick axons (greater than 0.7 micron diam.) of medial olivocochlear (MOC) neurons formed collaterals that terminated in the ventral cochlear nucleus, the interstitial nucleus of the vestibular nerve (in cats), and the inferior vestibular nucleus (in rodents).  

A low enzymatic activity is specific for neurons of the pons proper, inferior vestibular nucleus, trapezoid body of the inferior olivary complex, dentate nucleus of the cerebellum, reticular nucleus of the tegmen of Bekhterev's pons and posterior nucleus of Gudden's suture.  

Two main groups of area 7 efferences were found to project to vestibular complex: a) A first group terminates on vestibular nuclei (the inferior vestibular nucleus and the caudal part of the medial nucleus) mainly connected with cerebello-spinal system.  

Findings indicate a zonal organization in the uvula and nodulus projecting to the vestibular nuclei as follows; the Purkinje cells located in the medial half of the uvula except for the area along the posterolateral fissure project to the middle part of the inferior vestibular nucleus (IV) (middle IV zone); those in the lateral half of the uvula other than the laterocaudal part project to the caudal part of the IV (caudal IV zone); those in the mediorostral part of the nodulus and the middle part of the nodulus project to the middle part of the medial vestibular nucleus (MV) (middle MV zone); those in the lateral part of the nodulus project to the caudal part of the MV (caudal MV zone); those in the medial part of the uvula and nodulus along the posterolateral fissure project to the dorsal peripheral part of the superior vestibular nucleus (SV) (SV zone).  

Forelimb RNm, which also contains a face representation, projects to the lateral reticular nucleus, cell group f of the inferior vestibular nucleus, the facial nucleus, the main sensory nucleus of the trigeminal nerve, the caudal cuneate nucleus, the parvicellular reticular formation, and cervical segments of the spinal cord.  

In the human brain, the highest binding was seen in the cerebellum, inferior olivary nuclear complex, certain parts of the central gray matter, arcuate nuclei of the medulla oblongata and dorsal motor nucleus of the vagus, and densities of CGRP-binding sites were high in the nucleus accumbens, amygdala, tail of the nucleus caudatus, substantia nigra, ventral tegmental area, medial portion of the inferior colliculus, medial pontine nuclei, locus coeruleus, inferior vestibular nucleus, substantia gelatinosa of the spinal trigeminal nucleus, nucleus of the solitary tract and nucleus cuneatus lateralis.  

Primary vestibular afferents terminate mainly in rostral and caudal portions of the inferior vestibular nucleus (IVN), but do not reach cell group 'f'.  

Specific projection-zones to the inferior vestibular nucleus, lateral vestibular nucleus and the PH were not found.  

Mapping with stimulating electrodes revealed that stimulation of the lateral aspect of the medial vestibular nucleus and the medial aspect of the inferior vestibular nucleus evoked field potentials representing antidromic activation of contralateral dorsal cap neurons.  

Axons from the cerebellar cortex distribute mainly to vestibular areas which receive no primary afferent projections, e.g., the dorsal part of the lateral vestibular nucleus, the dorsolateral margin of the inferior vestibular nucleus as well as cell groups comparable to "f" and "x." In contrast, fastigial fibers show considerable overlap with primary vestibular input, particularly in the ventral part of the lateral nucleus, the central part of the inferior nucleus and the medial nucleus.  


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