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 1,315 records · Page 73Linked to original sources
PubMed1985

Onset and development of neuron-specific enolase immunoreactivity in the peripheral vestibular system of the mouse.

The development of neuron-specific enolase (NSE) immunoreactivity in mouse sensory and ganglion vestibular cells was studied from gestation day 14 to adulthood. NSE staining appeared sequentially in these structures with a pattern that closely paralled their maturation sequences. The onset of NSE reactivity, at gestation day 15, in ganglion cells was concomitant with the formation of contacts between the afferent fibers and sensory cells, and was observed in hair cells, at gestation day 17, during the period in which the first synaptic structures form. The development of NSE staining in the cristae revealed an apex-base and axial gradients of maturation.

Animals↗
PubMed1980

Vestibular inputs to the fastigial nucleus; evidence of convergence of macular and ampullar inputs.

1. Experiments have been undertaken on 11 decerebrate cats to investigate the effects of natural vestibular stimulation on the activity of cerebellar fastigial neurons. 2. From recordings in the rostral portion of the nucleus during sinusoidal lateral (roll) and horizontal (yaw) rotation, distinctive patterns of response were observed. 3. The majority of neurons sensitive to vestibular stimulation showed responses to a single modality of vestibular activation. During lateral tilt some neurones showed positional sensititivy, others gave responses related tothe velocity of movement. Other neurones responded in phase with the velocity of movement in the horizontal plane. 4. Aside from these neuronal responses, others provided indications of a convergence of inputs from different sets of vestibular receptors. In particular, several neurons showed a pattern of response that indicated tht they received inputs from otolith receptors and ampullar receptors of the vertical canal. At low velocities of movement their response was positional but with inreasing velocity the magnitude of the response increased and there was a marked phase shift of the discharge towards head velocity. 5. Neurons responding to horizontal rotation often showed positional responses during lateral tilt. There were also indications of a convergence of ampullar inputs from both vertical and horizontal canals. 6. The neural pathways mediating these resonses are discussed in consideration of previous neuroanatomical and neurophysiological data. We consider it likely that several pathways may act to evoke the patterns of response observed, and a role of the cerebellar cortex is indicated.

Acoustic Maculae↗
PubMed1993

Medial vestibular nucleus in the guinea-pig: apamin-induced rhythmic burst firing--an in vitro and in vivo study.

In a previous in vitro study, we have shown that guinea-pig medial vestibular nucleus neurons (MVNn) can be grouped into two main cell types based on their intrinsic membrane properties. Subsequent in vivo and in vitro studies demonstrated that these neurons are endowed with N-methyl-D-aspartate (NMDA) receptors and that NMDA induces rhythmic bursts in B MVNn. We now report the occurrence of rhythmic bursts in B MVNn (and in the subclass of B+LTS MVNn) which are induced by long-lasting perfusion of either apamin, a selective blocker of one type of Ca(2+)-dependent K+ conductance (SK channels), or by a high Mg2+/low Ca2+ artificial cerebrospinal fluid. Apamin-induced bursts were studied in vitro in brainstem slices, and in vivo in the alert unrestrained guinea-pig. In vitro, intracellular recordings demonstrated that the frequency of the bursts was voltage dependent. These bursts were insensitive to D-2-amino-5-phosphopentanoic acid but could be abolished by tetrodotoxin or blocked by the bath application of 20-50 microM of ouabain, a blocker of the sodium pump. In the in vivo preparation, unilateral infusion of apamin into the vestibular nuclei induced oscillatory head and eye movements. Our data show that the blockade of a Ca(2+)-activated K+ conductance may switch, in vitro and probably in vivo, the B MVn firing pattern from a regular to a bursting firing pattern.

2-Amino-5-phosphonovalerate↗
PubMed2004

PHR1, a PH domain-containing protein expressed in primary sensory neurons.

Previously, we identified PHR1 as an abundantly expressed gene in photoreceptors and showed that it encodes four isoforms, each with N-terminal pleckstrin homology (PH) and C-terminal transmembrane domains. To better understand PHR1 function and expression, we made a Phr1 null mouse by inserting a beta-galactosidase/neor cassette into exon 3. In addition to photoreceptors, we found abundant expression of specific Phr1 splice forms in olfactory receptor neurons and vestibular and cochlear hair cells. We also found Phr1 expression in cells with a possible sensory function, including peripheral retinal ganglion cells, cochlear interdental cells, and neurons of the circumventricular organ. Despite this discrete expression in known and putative sensory neurons, mice lacking PHR1 do not have overt sensory deficits.

Amino Acid Sequence↗
PubMed1991

Localization of substance P-like immunoreactivity in guinea pig vestibular endorgans and the vestibular ganglion.

The immunocytochemical distribution of substance P (SP) in guinea pig vestibular endorgans and the vestibular ganglion was investigated. Two kinds of SP-immunoreactive fibers were distinguished. Most were thick, and found around or beneath sensory hair cells. These SP-immunoreactive fibers were distributed predominantly on the slope of the crista and the peripheral region of the macula. By electron microscopy, we confirmed this type of SP-like immunoreactivity to be restricted within primary afferent neurons. Some vestibular ganglion cells also showed SP-like immunoreactivity, suggesting that SP is present in some primary afferent neurons, and is involved in afferent neurotransmission. The characteristic distribution of SP may indicate functional differences within each endorgan. The other group of immunoreactive nerve fibers, varicous thin fibers, could be found in the stroma of vestibular endorgans, nerve trunk, vestibular ganglion, and along blood vessels of the vestibular ganglion. These fibers may have a different origin, and have an influence on blood flow and certain other functions.

Animals↗
PubMed2001

Herpes simplex virus in the vestibular ganglion and the geniculate ganglion-role of loose myelin.

This study presents the first direct evidence for herpes simplex virus type 1 (HSV-1) infection in the neurons of the vestibular ganglion. Although many investigators have reported electron microscopic evidence of HSV-1 infection in sensory ganglia, HSV-1 infection in the vestibular ganglion has not been described. Vestibular ganglion neurons have a unique structure, with a loose myelin sheath instead of the satellite cell sheath that is seen in other ganglia. This loose myelin is slightly different from compact myelin which is known as too tight for HSV-1 to penetrate. The role of loose myelin in terms of HSV-1 infection is completely unknown. Therefore, in an attempt to evaluate the role of loose myelin in HSV-1 infection, we looked for HSV-1 particles, or any effects mediated by HSV-1, in the vestibular ganglion as compared with the geniculate ganglion. At the light microscopic level, some neurons with vacuolar changes were observed, mainly in the distal portion of the vestibular ganglion where the communicating branch from the geniculate ganglion enters. At the electron microscopic level, vacuoles, dilated rough endoplasmic reticulum and Golgi vesicles occupied by virus were observed in both ganglia neurons. In contrast, viral infections in Schwann and satellite cells were observed only in the geniculate ganglion, but not in the vestibular ganglion. These results suggest that loose myelin is an important barrier to HSV-1 infection, and it must play an important role in the prevention of viral spread from infected neurons to other cells.

Animals↗
PubMed1995

Immunocytochemical localization of the GTP-binding protein G0 alpha in the vestibular epithelium and ganglion of the guinea-pig.

The guanine nucleotide binding protein G0 alpha was immunolocalized in the guinea-pig vestibular system by confocal and electron microscopy. The vestibular sensory epithelia consist of the macula utriculi, macula sacculi and cristae ampullaris of the semicircular canals. Two types of hair cells are present in these epithelia. Type I hair cells are surrounded by an afferent nerve calyx that receives efferent innervation and type II hair cells are innervated directly by the afferent and efferent nerves. G0 alpha protein was observed on the inner face of the afferent calyceal membrane surrounding type I hair cells and in nerve endings in contact with type II hair cells. No labelling was found in the stereocilia and cuticular plate of type I and type II hair cells whereas the cytoplasmic matrix displayed a diffuse labelling. The plasma membrane of the supporting cells showed discreet labelling in the confocal microscope that are still confirmed by electron microscopy. A positive reaction was also observed along the plasma membrane of the vestibular ganglion neurons. Immunoblotting with affinity-purified polyclonal rabbit antibodies selective for the 39 kDa alpha subunit of G0 indicated that G0 alpha protein was present in both the vestibular ganglion. That G0 alpha labelling was observed in the cytoplasm of vestibular hair cells and in nerve endings contacting hair cells suggests that G0 may be involved in the modulation of vestibular neurotransmission.

Animals↗
PubMed1988

Synaptic mechanisms of interaction between Deiters' nucleus and the nuclei of some cranial nerves.

The effects of stimulation of the vestibular nerve, spinal trigeminal nucleus, facial and hypoglossal nuclei of the cranial nerves on the neuronal activity in the lateral vestibular nucleus of Deiters were studied in cats anaesthetized with pentobarbitone. Stimulation of these nuclei was found to produce antidromic and synaptic activation of Deiters' neurons. Descending axon collaterals of the vestibular neurons to these brainstem structures were revealed. Stimulation of the VIIIth nerve, spinal trigeminal and facial nuclei evoked mono- and polysynaptic excitatory postsynaptic potentials in Deiters' neurons. Stimulation of the spinal trigeminal nucleus evoked mono- and polysynaptic inhibitory postsynaptic potentials and disfacilitation in Deiters' neurons. In some vestibular neurons inhibitory postsynaptic potentials were also evoked by stimulation of the nucleus hypoglossus. Convergence of influences from these structures on Deiters' neurons was shown to exist. The peculiarities and functional significance of the effects mentioned are discussed.

Animals↗
PubMed1994

The fractional-order dynamics of brainstem vestibulo-oculomotor neurons.

The vestibulo-ocular reflex (VOR) and other oculomotor subsystems such as pursuit and saccades are ultimately mediated in the brainstem by premotor neurons in the vestibular and prepositus nuclei that relay eye movement commands to extraocular motoneurons. The premotor neurons receive vestibular signals from canal afferents. Canal afferent frequency responses have a component that can be characterized as a fractional-order differentiation (dkx/dtk where k is a nonnegative real number). This article extends the use of fractional calculus to describe the dynamics of motor and premotor neurons. It suggests that the oculomotor integrator, which converts eye velocity into eye position commands, may be of fractional order. This order is less than one, and the velocity commands have order one or greater, so the resulting net output of motor and premotor neurons can be described as fractional differentiation relative to eye position. The fractional derivative dynamics of motor and premotor neurons may serve to compensate fractional integral dynamics of the eye. Fractional differentiation can be used to account for the constant phase shift across frequencies, and the apparent decrease in time constant as VOR and pursuit frequency increases, that are observed for motor and premotor neurons. Fractional integration can reproduce the time course of motor and premotor neuron saccade-related activity, and the complex dynamics of the eye. Insight into the nature of fractional dynamics can be gained through simulations in which fractional-order differentiators and integrators are approximated by sums of integer-order high-pass and low-pass filters, respectively. Fractional dynamics may be applicable not only to the oculomotor system, but to motor control systems in general.

Brain Stem↗
PubMed1998

Identification of mRNA transcripts and immunohistochemical localization of Na/H exchanger isoforms in gerbil inner ear.

Recent physiological and pharmacological studies have implicated involvement of the Na/H exchanger (NHE) in regulating inner ear ion homeostasis, but the cellular distribution of this membrane transporter remains unknown. Here reverse transcription and the polymerase chain reaction (RT-PCR) were employed to screen adult gerbil inner ears for mRNA transcripts encoding the four best characterized isoforms of NHE. PCR products spanning selected segments of NHE mRNAs were cloned and sequenced. The putative housekeeping gene NHE-1 was found to be expressed and the 459 bp product shared 98.7% amino acid homology with rat sequence. NHE-2, NHE-3 and NHE-4 cDNA transcripts likewise were detected and the PCR products shared 100, 99.4 and 88.9% amino acid homology, respectively, with their rat counterparts. In addition, the cellular distribution of NHE isoforms 1 and 3 was mapped in the gerbil inner ear by immunostaining with polyclonal antisera against rat antigens. In the cochlea, the antiserum against NHE-1 reacted strongly at the basolateral membrane of strial marginal cells as well as with inner and outer hair cells and spiral ganglion neurons. Less intense staining for NHE-1 was present in subpopulations of fibrocytes in the spiral limbus and in inferior and superior areas of the spiral ligament. In the vestibular system dark and transitional cells expressed abundant NHE-1 as did hair cells and vestibular ganglia neurons. Immunostaining with the antiserum against NHE-3 was limited to the apical surface of marginal cells in the stria vascularis. Based on these data, NHE-1 likely functions primarily to maintain intracellular pH levels in cells where it is found in high abundance. NHE-3, on the other hand, possibly participates in the vectorial transcellular movement of Na+ by strial marginal cells thus helping to maintain the extremely low Na+ level in cochlear endolymph.

Animals↗
PubMed2005

[Morphological and functional alterations of ear in lysosomal neuraminidase gene deficient mouse].

OBJECTIVE: To observe the alterations of the auditory function and morphology of the ear in the mouse sialidosis models which has been generated by targeted deletion of lysosomal neuraminidase gene (Neul) and closely resembled the phenotypes in corresponding human conditions, and to explore pathophysiological mechanisms of hearing impairment. METHODS: Neul homozygous (Neul -/-) mice at 3 weeks, 2 and 4 months of age, and their wildtype littermates (Neu1 +/+) were examined for auditory thresholds through auditory brainstem responses (ABR) to click, 8, 16, and 32 kHz stimuli. Morphological analyses in ears were performed by series temporal bone section and light microscopy. RESULTS: Neul -/- mice at 3 weeks of age showed an elevated ABR threshold, 50-55 dB above those of Neul +/+ mice. Up to 2 and 4 months of age, their thresholds were further elevated for 60-68 dB. There were distinct pathological changes of middle and inner ear of 3 weeks of age in Neul -/- mice, especially at 2-4 months of age there were significant cerumen occlusion in the external auditory canal and severe otitis media. Vacuolation associated with lysosomal storage was observed within ossicles and cochlear bone cells, stria vascularis cells, spiral ganglion neurons and macrophages, spiral limbus, spiral prominence, Reissner's membrane cells, and the mesothelial cells of the perilymphatic scala and basilar membrane, but not within the organ of Corti. Vestibular ganglion neurons, hair cells and supporting cells in cristae and maculae also showed vacuolation. CONCLUSIONS: The deficiency of lysosomal neuraminidase may result in a serious hearing loss and morphological alterations of ear. The external auditory canal obstruction, otitis media and ossicle changes may cause conductive hearing loss, and the defects in lysosomal storage of neurons, stria vascularis, spiral limbus, Reissner's membrane and basilar membrane cells may contribute to sensorineural deafness.

Animals↗
PubMed1993

Testing the common neural integrator hypothesis at the level of the individual abducens motoneurones in the alert cat.

1. As far as horizontal eye movements are concerned, the well-known hypothesis of a common neural integrator states that the eye-position signal is generated by a common network, regardless of the type of versional movement. The aim of this study was to evaluate the validity of this hypothesis by analysing the behaviour of the abducens motoneurones, the system into which the horizontal neural integrator(s) project(s). If there were a common neural integrator, the different motoneurones would receive the eye position signal through the same pathway and the sensitivity to eye position would be the same regardless of the type of versional movement. If there were multiple integrators, the sensitivity to eye position in one type of versional movement might be different from the sensitivity to eye position in another type of versional movement, at least for occasional motoneurones. 2. The discharge of thirty-one antidromically identified abducens motoneurones was recorded in the alert cat during spontaneous eye movements made in the light and in response to sinusoidal rotations of the head in complete darkness. 3. All of the abducens motoneurones exhibited a burst of action potentials for lateral saccades. During fixation between saccades, they maintained a steady firing rate that increased as the cat fixated increasingly lateral eye positions. 4. For each abducens motoneurone, the sensitivity to eye position (Kf) was determined from measurements carried out during intersaccadic fixations. Kf was calculated from the slope of the firing rate-eye position linear regression line. 5. The discharge rate of the identified motoneurones was observed during four sinusoidal vestibular stimulations (+/- 10 deg, 0.10 Hz; +/- 20 deg, 0.10 Hz; +/- 30 deg, 0.10 Hz; +/- 40 deg, 0.10 Hz). The motoneurones exhibited a burst of activity during fast phases in the lateral direction and paused during fast phases in the opposite direction. During slow phases, motoneurones modulated their activity as a function of the vestibularly induced eye movements except for slow phases that occurred in position ranges below their recruitment threshold. In these cases their activity was cut off. 6. A new method was developed to measure the sensitivity to eye position of neurones during vestibular slow phases. The difficulty came from the fact that, during slow phases, eye velocity and eye position changed simultaneously and that each of those two variables could influence neuronal activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗