Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Vestibular Neuronitis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed2000

Connections of Purkinje cell axons of lobule X with vestibulocerebellar neurons projecting to lobule X or IX in the rat.

Connections of Purkinje cell axons of lobule X (nodulus) with vestibulocerebellar neurons projecting to lobule X or IX (uvula) were revealed in the rat. Purkinje cell axons were anterogradely labeled with biotinylated dextran (BD) injected into sublobule Xa while vestibular neurons were retrogradely labeled with cholera toxin subunit B (CTB) injected into sublobule Xa or IXc. Labeled terminals of Purkinje cell axons of lobule X were numerous in the superior vestibular nucleus (SV), medial parts of the parvocellular (MVpc) and the caudal part (MVc) of the medial vestibular nucleus (MV), and group y. These subdivisions of the vestibular nuclei contained many neurons projecting to lobule X or IX. Lobule-X-projecting and lobule-IX-projecting neurons were in contact with terminals of Purkinje cell axons of lobule X in the MVpc and MVc. They were distributed dorsally to medially in medial parts of the MVpc and MVc. The present study suggests that Purkinje cells in lobule X regulate the output of a population of lobule-X-projecting or lobule-IX-projecting neurons of the MVpc and MVc.

Adjuvants, Immunologic↗
PubMedDate not supplied

Secondary vestibular and neck position signals in the vestibular nuclei of alert rhesus monkeys performing active head movements.

Rhesus monkeys were trained to track a visual target with head and eye movements in order to study central vestibular neurons under natural conditions. Single unit recordings of cells in the vestibular nuclei were obtained during active head rotations in the horizontal plane, and also during passive copies of these self-induced movements. Most cells exhibited secondary responses immediately following the primary vestibular responses to active or passive rapid head movements. They were of opposite polarity to the primary responses, and generally rate enhancements of secondary responses were of greater amplitude than rate suppressions. In addition, vestibular nuclei cells also encoded tonic neck position. The corresponding signal consisted of a variation in the basal discharge rate as a function of neck, and thus head, position. These observations prove for the first time that dynamic and static response characteristics recorded earlier from lesioned brains and under anaesthesia are, at least qualitatively, representative for the normally behaving vestibulomotor system in primates.

Animals↗
PubMed2001

Age-related change in the number of neurons in the human vestibular ganglion.

Dysequilibrium of aging in humans has been speculated to arise from progressive deterioration within anatomical components of the vestibular system. An integral part of this system is vestibular ganglions, which are bipolar neurons that relay peripheral vestibular information to the central nervous system. To assess the effect of aging on the number of human vestibular ganglion neurons, assumption-free stereology in the form of the optical fractionator was used on 20 serially sectioned archival human temporal bone specimens. Donors had no history of vestibular pathology and ranged in age from 2 to 88 years. An average of 25,812 (coefficient of variation = 0.13) vestibular ganglion neurons was found throughout this age range, a significant departure from the results of past studies. Logistics-based regression analysis pointed to a nonlinear pattern of decline in the neuronal population: the number of cells remained roughly constant at about 28,952 cells in youth and then declined gradually between 30 and 60 years of age before leveling off at approximately 23,349 cells in older individuals. This study confirmed the existence of an age-related decline in the primary neurons of the human vestibular system, thus providing one anatomical basis for the increased incidence of imbalance seen with age.

Adolescent↗
PubMed1982

[Spatial organization of vestibular effects on neurons of the fastigial nucleus in the cat].

Cerebellar fastigial neurons activated by stimulation of vestibular nerve and the lateral vestibular nucleus of Deiters, were studied in cats. Over 2/3 of the neurons synaptically activated by stimulation of vestibular nerve are localized in the caudal half of the fastigial nucleus. Over half of these fastigial neurons could be activated antidromically by stimulation of the contralateral Deiters nucleus. 81% of these neurons antidromically activated by stimulation of ventral region of the contralateral Deiters nucleus were distributed in the caudal half of the fastigial nucleus and the remaining 19%--in the rostral part of the nucleus. Bilateral stimulation of the dorsal part of Deiters' nucleus antidromically activated the fastigial neurons in medial and rostral regions of the nucleus. There was no fastigial neuronal projections to the ventral half of the ipsilateral Deiters' nucleus. Orthodromic action potentials could be produced by stimulation of the ipsilateral Deiters' nucleus in the neurons of rostral part of the fastigial nucleus.

Animals↗
PubMed1997

Survival of inner ear sensory neurons in trk mutant mice.

Analysis of trkB-/-; trkC-/- double mutant mice revealed that peripheral and central inner ear sensory neurons are affected in these mice. However, a substantial amount of cochlear and vestibular neurons survive, possibly due to maintenance or upregulation of TrkA expression. To clarify the function of the TrkA receptor during development of the cochlear and vestibular ganglion we analysed trkA-/- mice and the expression of this receptor in inner ear sensory neurons of trkB-/-; trkC-/- animals. TrkA homozygous mutant mice showed normal numbers of neurons and no TrkA expression was detected in neurons of trkB-/-; trkC-/- double mutant mice. We conclude that TrkA is not essential for inner ear development and that in the absence of any of the known catalytic Trk receptors peripheral inner ear sensory neurons are prone to undergo cell death or must use a different signaling mechanism to survive.

Animals↗
PubMed1987

Modulation by eye position of neck muscle contraction evoked by electrical labyrinthine stimulation in the alert cat.

Modulation of vestibulo-spinal reflexes by gaze is a model system for studying interactions between voluntary and reflex motor activity. In the alert cat, the EMG of Splenius and Obliquus capitis muscles increases with ipsilateral gaze eccentricity during spontaneous eye movements. Labyrinth stimulation by current pulses evokes EMGs with latencies consistent with a three neuron vestibulocollic pathway. The amplitude of evoked activity increases with eye position. The directions in which eye movements increase EMG was usually the same for both spontaneous and induced EMG activity, namely, horizontal and ipsilateral. However, sometimes the increase in spontaneous EMG occurred with horizontal eye position, whereas the induced EMG changed with vertical eye position. Spontaneous and evoked EMG are then modulated by different eye position signals. Command signals reflecting eye position probably reach two different types of neurons in the vestibulo-collic pathway, most likely secondary vestibular neurons and neck muscle motoneurons.

Animals↗
PubMed1983

EMG responses of the vertical eye muscles to dynamic and static natural vestibular stimulation about different axes in alert rabbits.

The EMG responses of the vertical eye muscles have been recorded in alert intact rabbits submitted to both dynamic and static natural vestibular stimulations about different axes. Following dynamic vestibular stimulation, the phase lead of the EMG response with respect to head position as well as its sensitivity increased with stimulus frequency in all the stimulation modalities. This indicates a progressive recruitment by the stimulus of the second-order vestibular neurons related to semicircular canals. The sensitivity of the response was consistently higher in the effective intermediate roll-pitch modality for all the 4 muscles. Following static stimulation, the EMG response showed an asymmetric modulation. The excitatory response was always higher than the inhibitory one and linearly related with the stimulus. Also for the static stimulation the amplitude of the response was significantly higher when the animal was tilted about the effective intermediate roll-pitch axis for all the 4 muscles. The presence of a maximal EMG response in the same modality for both static and dynamic stimulation indicates a similar spatial organization of those subgroups of ampullar and macular receptors projecting to the same eye muscle.

Acoustic Stimulation↗
PubMed1996

Does long-term potentiation occur in guinea-pig Deiters' nucleus?

Long-term potentiation (LTP) was studied in the lateral vestibular nucleus (LVN-Deiters' nucleus) in guinea-pigs in vivo. Field potentials and extracellular single unit discharges were recorded in the LVN following electrical stimulation of the ipsilateral VIIIth nerve. High-frequency stimulation (HFS) of the VIIIth nerve fibres produced LTP of the monosynaptic component of the vestibular field potential. The LTP of the field potentials was paralleled by an increase of the evoked spike activity. Intranuclear administration of the NMDA antagonist MK-801 prevented LTP of the monosynaptic component of the vestibular field potentials and significantly suppressed the spontaneous firing of lateral vestibular neurones in a dose-dependent fashion. These results demonstrate that synapses between primary afferent fibres and second order LVN neurones undergo long lasting changes following HFS of the ipsilateral vestibular nerve.

Animals↗
PubMed1988

Electrophysiological properties of the isolated vestibulocerebellar complex of the frog in vitro.

Parameters of the electrical activity of the isolated vestibulocerebellar complex of the frog were studied under in vitro conditions. In the region of the vestibular nucleus (nc. VIII), in the presence of stimulation of the stato-acoustic nerve (n. VIII), responses from efferent vestibular neurones and from unidentified (probably vestibulospinal) neurones were recorded. The latent periods of their excitatory postsynaptic potentials (EPSPs, 1.4-2.2 ms) were indicative of mono- and disynaptic connection. Inhibitory postsynaptic potentials (IPSPs) were also observed. Stimulation of the auricular lobe of the cerebellum evoked monosynaptic IPSPs, an EPSP-IPSP complex or pure EPSPs in nc. VIII, the latter probably by way of collaterals to the cerebellum. The inhibitory character of the effect of efferents from the cerebellum to the neurones of nc. VIII was demonstrated in the focal synaptic potential and in spontaneous and evoked unit activity. If n. VIII was stimulated, both focal and unit extra- and intracellular responses characteristic of activation of the Purkinje cells by mossy (MF) or climbing (CF) afferent fibres were recorded in the cerebellar cortex. The electrophysiological picture indicates that both synaptic transmission and the functional manifestations of the individual neurones are preserved in the tested preparation.

Animals↗
PubMed2000

Unbiased stereological quantification of neurons in the human vestibular ganglion.

Vestibular ganglion (VG) neurons are bipolar neurons that relay peripheral vestibular information to the CNS. Neuron counts in normal humans provide a basis for quantitative studies on the effects of aging or pathological conditions in the audiovestibular systems. No prior study has employed unbiased stereological technique to count human VG neurons. This study used unbiased stereology in the form of the optical fractionator to estimate the total number of human VG neurons in archival temporal bone specimens. An average (+/- s.d.) of 27330+/-2593 neurons was found in specimens from five patients with no history of vestibular pathology. This result, a significant departure from results of past studies, provides the first unbiased baseline value to compare with future stereologically based studies on the human VG.

Adolescent↗
PubMed1978

Cerebellar afferent projections from the vestibular nuclei in the cat: an experimental study with the method of retrograde axonal transport of horseradish peroxidase.

Details of cerebellar afferent projections from the vestibular nuclei were investigated by the method of retrograde axonal transport of horseradish peroxidase (HRP) in the cat. The distribution of labeled cells in the vestibular nuclei following HRP injections in various parts of the cerebellum indicates that vestibular neurons in the medial and descending nuclei and cell groups f and x project bilaterally to the entire cerebellar vermis, the flocculus, the fastigal nucleus and the anterior and posterior interpositus nuclei. In addition, labeled cells (giant, medium and small) were consistently found bilaterally in the superior and lateral vestibular nuclei following HRP injections in the nodulus, flocculus, fastigal nucleus, and following large injections in the vermis. No labeled cells were observed in cases of HRP injections in crus I and II, the paramedian lobule, paraflocculus and lateral cerebellar nuclei. The present findings indicate that secondary vestibulocerebellar fibers project to larger areas in the cerebellum and originate from more subdivisions and cell groups of the vestibular nuclear complex than previously known.

Animals↗
PubMed1993

Survival of Scarpa's ganglion in the profoundly deaf human.

The electrically evoked auditory brain stem response in some cochlear implant patients may be confounded by evoked potentials generated by vestibular neurons. The magnitude of this contribution to the response from the vestibular system is unknown, in part because the survival of cells within Scarpa's ganglion in profoundly deaf humans is unknown. Therefore, we undertook a quantitative study of Scarpa's ganglion in 48 deaf subjects who in life would have been candidates for cochlear implantation and in 5 subjects with normal hearing. The numbers of residual cells in both Scarpa's ganglion and the spiral ganglion in deaf subjects were significantly less than in individuals with normal hearing. Bivariate analysis demonstrated a highly significant positive correlation between cell counts of Scarpa's ganglion and the spiral ganglion. The durations of hearing loss and of profound deafness were negatively correlated with Scarpa's ganglion cell counts. However, in contrast to spiral ganglion cell survival, the cause of profound deafness did not predict the number of Scarpa's ganglion cells. Multiple linear regression analysis using a variety of clinical parameters demonstrated that the best predictor of the number of Scarpa's ganglion cells in profoundly deaf humans was the number of remaining spiral ganglion cells.

Adult↗
PubMed1995

Vestibular modulation of the septo-hippocampal cholinergic system of rats.

Effects of vestibular stimulation on the in vivo release of hypothalamic histamine and hippocampal acetylcholine (ACh) were investigated in urethan-anesthetized rats, using a brain microdialysis method. Changes in glutamate concentration in the medial vestibular nucleus (MVN) were also monitored by a microbiosensor technique using a glutamate oxidase-embodied platinum electrode. Caloric stimulation with hot water increased the glutamate release in the MVN, while that with ice water decreased it. It is evidenced that glutamate is a neurotransmitter between afferent vestibular nerve and the MVN. Electrical stimulation of the round window evoked the release of hypothalamic histamine and hippocampal ACh and these effects were inhibited by the blockade of second-order vestibular neurons by the pre-injection of 6,7-dinitroquinoxaline-2,3-dione (DNQX), an antagonist of non-N-methyl-D-aspartate (non-NMDA) glutamate receptors, into the ipsilateral vestibular nucleus. Caloric stimulation with both hot and ice water increased the release of hypothalamic histamine and hippocampal ACh. It is suggested that both the histaminergic and cholinergic systems were activated by the imbalance of intervestibular activities. Depletion of neuronal histamine by alpha-fluorometylhistidine (FMH), an irreversible inhibitor of histamine synthesis, did not suppress the vestibular evoked release of hippocampal ACh. In contrast, caloric stimulation did not evoke hypothalamic histamine release in rats treated with ethylcholine aziridiniun ion (AF64A), a putative cholinotoxin. All these findings suggest that the vestibular information activated the histaminergic neurons via the activation of the cholinergic neurons and this neuronal circuit was involved in the vestibulo-autonomic response.

Acetylcholine↗
PubMed1985

Effects of lesion of the interstitial nucleus of Cajal on vestibular horizontal canal neurons in the cat.

Effects of procaine infusion into the interstitial nucleus of Cajal (INC) on vestibular nuclear neurons related to the horizontal canal were studied in cats anesthetized with nitrous oxide and paralyzed with gallamine. Neurons that responded to sinusoidal horizontal rotation (at 0.18 Hz) were recorded extracellularly in the medial and descending vestibular nuclei. Spontaneous activity of type I neurons increased, whereas that of type II neurons decreased following procaine infusion into the ipsilateral INC. Gain of the neuronal response to horizontal rotation decreased after the ipsilateral INC infusion, but there was no consistent effect on phase. Infusion into the contralateral INC seemed less effective. Similar effects were obtained with electrolytic lesions that were confined to the ipsilateral INC area. These results suggest that the INC influences type I neurons through inhibitory action of type II neurons and that it eventually controls the gain, but not the phase, of the horizontal vestibular reflexes.

Animals↗
PubMed1992

Vestibular short latency responses to pulsed linear acceleration in unanesthetized animals.

Linear acceleration transients were used to elicit vestibular compound action potentials in non-invasively prepared, unanesthetized animals for the first time (chicks, Gallus domesticus, n = 33). Responses were composed of a series of up to 8 dominant peaks occurring within 8 msec of the stimulus. Response amplitudes for 1.0 g stimulus ranged from 1 to 10 microV. A late, slow, triphasic, anesthesia-labile component was identified as a dominant response feature in unanesthetized animals. Amplitudes increased and latencies decreased as stimulus intensity was increased (MANOVA P less than 0.05). Linear regression slope ranges were: amplitudes = 1.0-5.0 microV/g; latencies = -300 to -1100 microseconds/g. Thresholds for single polarity stimuli (0.035 +/- 0.022 g, n = 11) were significantly lower than those of alternating polarity (0.074 +/- 0.028 g, n = 18, P less than 0.001). Bilateral labyrinthectomy eliminated responses whereas bilateral extirpation of cochleae did not significantly change response thresholds. Intense acoustic masking (100/104 dB SL) produced no effect in 2 animals, but did produce small to moderate effects on response amplitudes in 7 others. Changes were attributed to effects on vestibular end organs. Results of unilateral labyrinth blockade (tetrodotoxin) suggest that P1 and N1 preferentially reflect ipsilateral eighth nerve compound action potentials whereas components beyond approximately 2 msec reflect activity from vestibular neurons that depend on both labyrinths. The results demonstrate that short latency vestibular compound action potentials can be measured in unanesthetized, non-invasively prepared animals.

Acceleration↗
PubMed2003

Postlesional vestibular reorganization improves the gain but impairs the spatial tuning of the maculo-ocular reflex in frogs.

The ramus anterior (RA) of N.VIII was sectioned unilaterally. Two months later we analyzed in vivo responses of the ipsi- and of the contralesional abducens nerve during horizontal and vertical linear acceleration in darkness. The contralesional abducens nerve had become responsive again to linear acceleration either because of a synaptic reorganization in the vestibular nuclei on the operated side and/or because of a reinnervation of the utricular macula by regenerating afferent nerve fibers. Significant differences in the onset latencies and in the acceleration sensitivities allowed a separation of RA frogs in a group without and in a group with functional utricular reinnervation. Most important, the vector orientation for maximal abducens nerve responses was clearly altered: postlesional synaptic reorganization resulted in the emergence of abducens nerve responses to vertical linear acceleration, a response component that was barely detectable in RA frogs with utricular reinnervation and that was absent in controls. The ipsilesional abducens nerve, however, exhibited unaltered responses in either group of RA frogs. The altered spatial tuning properties of contralesional abducens nerve responses are a direct consequence of the postlesional expansion of signals from intact afferent nerve and excitatory commissural fibers onto disfacilitated 2nd-order vestibular neurons on the operated side. These results corroborate the notion that postlesional vestibular reorganization activates a basic neural reaction pattern with more beneficial results at the cellular than at the network level. However, given that the underlying mechanism is activity-related, rehabilitative training after vestibular nerve lesion can be expected to shape the ongoing reorganization.

Abducens Nerve Injury↗
PubMed1983

Responses of semicircular canal and otolith afferents to small angle static head tilts in the gerbil.

The discharge activity of first-order vestibular neurons was recorded in anesthetized or decerebrated gerbils from the post-ganglionic fibers of the vestibular nerve. Semicircular canal afferents were distinguished from otolith afferents on the basis of their responses to linear and angular head acceleration. In decerebrated preparations, canal afferents exhibited significantly faster discharge activity (average = 87.8 impulses/s) than that of canal afferents in anesthetized preparations (average = 66.2 impulses/s), when the head was held to position the lateral semicircular canals coplanar with the earth horizontal plane (standard position). The effects of changes in linear forces on vestibular afferent activity were determined by statically tilting the head +/- 10 degrees about either the fore-aft and/or left-right head axes. A change in activity, from that recorded in the standard position, of 10% or greater was considered significant. Using this criterion, significant changes in the tilt response in anesthetized animals were observed in both anterior (23 of 48 neurons, 48%) and lateral (22 of 31, 71%) canal afferents as well as otolith (18 of 25, 72%) afferents. In decerebrated preparations for tilts around the pitch (left-right) axis, comparable effects were measured in (19 of 36, 53%) anterior and (17 of 30, 57%) lateral canal afferents. Neurons with irregular firing activity were more likely than regularly firing canal afferents to change their average discharge rate during static tilt. No significant differences in response magnitude to +/- 10 degrees head tilt were found between canal and otolith afferents in anesthetized animals. Mechanisms to account for the responses to linear acceleration of canal afferents are discussed.

Afferent Pathways↗
PubMed1996

c-fos Expression in the rat brain after unilateral labyrinthectomy and its relation to the uncompensated and compensated stages.

The expression of the immediate early gene c-fos has been studied in the entire brain of rats 3, 6 and 24 h after surgical unilateral labyrinthectomy. We combined in situ hybridization for c-fos messenger RNA with immunocytochemistry for Fos protein to document very early changes in c-fos expression and to identify with cellular resolution neuronal populations activated by unilateral labyrinthectomy. Three hours after unilateral labyrinthectomy a bilateral increase in both c-fos messenger RNA and protein levels was seen in the superior, medial and spinal vestibular nuclei, nucleus Y, and prepositus hypoglossal nucleus. These changes were asymmetric in the medial vestibular nucleus, being most prominent in the dorsal part of the contralateral nucleus (where second order vestibular neurons are located) and in the ventral part of the ipsilateral nucleus (where commissural neurons acting on the medial vestibular nucleus of the intact side are located). An increase in c-fos messenger RNA expression was seen bilaterally, but with an ipsilateral predominance, in the vermal and paravermal areas of the cerebellar cortex, flocculus and paraflocculus, as well as in the precerebellar lateral and paramedian reticular nuclei. c-fos messenger RNA and protein levels increased in a few regions of the contralateral inferior olive. A predominantly ipsilateral increase in c-fos expression also occurred in the caudate-putamen. A bilateral but not exactly symmetric increase in both c-fos messenger RNA and protein levels was present in several nuclei of the dorsal pontine tegmentum (parabrachial nucleus, locus coeruleus and laterodorsal tegmental nucleus), mesencephalic periaqueductal gray, and several hypothalamic, thalamic and cerebrocortical regions. No change was seen in the cerebellar nuclei, lateral vestibular nucleus and red nucleus. The increased expression of c-fos observed 3 h after unilateral labyrinthectomy, in conjunction with the sudden occurrence of postural and motor deficits, usually declined 6-24 h after the lesion, i.e. during the development of vestibular compensation. In the dorsal part of the medial vestibular nucleus, however, the pattern of c-fos expression observed 3 h after unilateral labyrinthectomy was reversed 6-24 h after the lesion: both c-fos messenger RNA and protein levels increased on the ipsilateral side, but greatly decreased on the contralateral side. In conclusion, asymmetric changes in c-fos expression occurred within 3 h after unilateral labyrinthectomy, but gradually declined or reversed 6 and 24 h after the lesion, thus being temporally related to the appearance and development of vestibular compensation.

Animals↗