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 235 records · Page 13Linked to original sources
PubMed1978

Properties of central vestibular neurons fired by stimulation of the saccular nerve.

In 4 cats all vestibular afferents in one labyrinth except those innervating the saccular macula were transected and allowed to degenerate. 23--53 days after the initial surgery the central connections of the remaining saccular nerve were studied under chloralose anesthesia. Stimulation of the saccular nerve evoked N1 field potentials in the ipsilateral lateral and descending vestibular nuclei; little or no field potential activity was seen in the superior nucleus. The distribution of field potentials overlapped with that of neurons of origin of the vestibulospinal tracts. Forty-two neurons in the ipsilateral vestibular nuclei, many in the lateral nucleus, responded, often monosynaptically, to stimulation of the saccular nerve with single or double shocks; some of the neurons projected to the spinal cord. All saccular-fired neurons were tested for commissural actions by stimulation of the contralateral vestibular nerve. Many were facilitated, almost none were inhibited. In agreement with earlier work, we conclude that commissural inhibition may be a property of the canal system only.

Afferent Pathways↗
PubMed1990

Vertical eye movement-related secondary vestibular neurons ascending in medial longitudinal fasciculus in cat I. Firing properties and projection pathways.

1. The firing characteristics and projection patterns of secondary vestibular nucleus neurons involved in the vertical vestibuloocular pathways were investigated in alert cats. Single-unit recordings were made in the medial longitudinal fasciculus (MLF) near the trochlear nucleus from axons that were monosynaptically activated after electrical stimulation of the vestibular nerve. In a total of 253 identified secondary neurons, 225 discharged in relation to vertical eye movements; 189 of these increased their firing rate for downward eye movements and 36 for upward movements. The activity of the remaining 28 axons was not related to eye movements when the head was still. 2. Virtually all of the secondary neurons with downward on-direction displayed tonic activity that was primarily related to steady eye position during fixation (DPV neurons). The slope of the relationship between firing rate and vertical eye position ranged from 1.2 to 9.1 (spikes/s)/deg with a mean of 3.2 (spikes/s)/deg. The regularity of firing was quantified by calculating the coefficient of variation (CV) of interspike intervals. A comparison of the CV in the population units indicated that DPV neurons could be classified as either regular or irregular neurons. There was a tendency for regular neurons to have higher firing rates and higher correlation coefficients for the rate-position relationships than irregular neurons. 3. During pitch rotation in the light, all the DPV neurons tested increased their firing rate with upward head rotation. Both the phase and the amplitude of the response indicated that DPV neurons discharged not only in relation to eye position but also in relation to head velocity, suggesting that they received monosynaptic input from the posterior semicircular canal. The gain and phase lag of the response relative to head velocity were measured at 0.5 Hz. The range of the gain was 1.1-5.1 (spikes/s)/(deg/s), and that of the phase lag was 18.3-62.4 degrees. There was a tendency for irregular DPV neurons to have a larger gain and smaller phase lag than regular DPV neurons. 4. Ascending and descending projection pathways were determined for 147 DPV axons. Of these, 69 ascended in the contralateral MLF with respect to their soma (crossed-DPV axons), and 78 in the ipsilateral MLF (uncrossed-DPV axons), as revealed by their monosynaptic activation from the contralateral or ipsilateral vestibular nerve. Stimulation of the caudal MLF at the level of the obex evoked direct responses caused by antidromic activation of descending collaterals in approximately 70% (49/69) of the crossed-DPV axons.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1984

[Method for in vitro recording of vestibular neurons of the inner ear during postnatal development in the mouse].

Unitary recordings of spontaneous activity were performed from vestibular ganglion perikaria and axons of Mouse inner ear explants. The latter were from 1-11 day postnatal mice and were maintained in vitro at 37 degrees C, in a defined bathing medium. Spontaneous action potentials were obtained at each developmental stage and presented the distinctive features of the in vivo recorded activities during normal development. On the 3rd day post partum the recorded activities were of the immature type, with slow irregular discharge frequencies. In ganglia 3 to 9 days post partum the spike frequencies increased and the discharges exhibited 3 distinct firing patterns. This electrophysiological maturation of vestibular receptors is discussed in comparison with the morphological maturation of the vestibular organ during the same postnatal period.

Action Potentials↗
PubMed1979

The velocity response of vestibular nucleus neurons during vestibular, visual, and combined angular acceleration.

In alert Rhesus monkeys neuronal activity in the vestibular nuclei was measured during horizontal angular acceleration in darkness, acceleration of an optokinetic stimulus, and combined visual-vestibular stimulation. The working ranges for visual input velocity and acceleration extend up to 60 degrees/s and 5 degrees/s2. The corresponding working range for vestibular input acceleration is wider and time-dependent. During combined stimulation, that is acceleration of the monkey in the light, a linear relation between neuronal activity and velocity could be established for all neurons. Type I vestibular plus eye movement neurons displayed the greatest sensitivity and had a small linear range of operation. Other vestibular neurons were less sensitive but had a larger range of linear response to different values of acceleration. Accelerating the animal and visual surround, simultaneously but in opposite directions, results in neuronal activity proportional to relative velocity over a limited range.

Acceleration↗
PubMed1990

Vertical eye movement-related secondary vestibular neurons ascending in medial longitudinal fasciculus in cat. II. Direct connections with extraocular motoneurons.

1. The preceding study in the alert cat has shown that many secondary vestibular axons that ascend in the medial longitudinal fasciculus (MLF) increase their firing rate in proportion to downward eye position. In the present study, projection and termination of these downward-position-vestibular (DPV) neurons within extraocular motoneuron pools were studied electrophysiologically by spike-triggered averaging techniques and morphologically be reconstructing their axonal trajectory after intra-axonal injection of horseradish peroxidase (HRP). 2. Extracellular field potentials recorded within the trochlear nucleus and/or the inferior rectus subdivision of the oculomotor nucleus were averaged by the use of spike potentials of single DPV neurons as triggers. All the crossed-DPV axons tested induced negative unitary field potentials in the trochlear nucleus (n = 9) and in the inferior rectus subdivision of the oculomotor nucleus (n = 5), suggesting that they made monosynaptic excitatory connection with motoneurons in these nuclei. The four crossed-DPV axons tested in the two motoneuron pools induced unitary field potentials in both. The majority of crossed-DPV axons terminated in these nuclei were directly activated from the caudal MLF, indicating that they had descending collaterals projecting to the spinal cord as well. The uncrossed-DPV axons did not induce such unitary field potentials either in the trochlear nucleus (n = 4) or in the inferior rectus subdivision (n = 3). 3. All the uncrossed-DPV axons examined (n = 14) induced positive unitary field potentials in the superior rectus subdivision of the oculomotor nucleus, suggesting that they made monosynaptic inhibitory connections with motoneurons innervating the superior rectus muscle. These uncrossed-DPV axons displayed regular firing patterns and were not activated from the caudal MLF. None of the crossed-DPV axons tested (n = 4) induced unitary field potentials in the superior rectus subdivision. 4. Five crossed-DPV axons were injected with HRP. All these axons ascended in the MLF contralateral to their soma, gave off many collaterals to the trochlear nucleus, and projected more rostrally. For three well-stained axons, numerous terminal branches were also found in the rostroventral part of the contralateral oculomotor nucleus, the area corresponding to the inferior rectus subdivision. Some collaterals in the oculomotor nucleus recrossed the midline to terminate in the medial part of the ipsilateral oculomotor nucleus. Other terminations were observed in the interstitial nucleus of Cajal and in the periaqueductal gray adjacent to the oculomotor nucleus. The crossed axons injected included both regular and irregular types, and three of the four examined were activated from the caudal MLF.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1982

Identification of multiple groups of efferent vestibular neurons in the adult pigeon using horseradish peroxidase and DAPI.

This study was designed to investigate the efferent innervation of the pigeon labyrinth. Horseradish peroxidase (HRP) was injected and confined within the endolymphatic space of one labyrinth in 9 adult pigeons. The brain was perfused by transcardiac carotid catheterization and the HRP reacted by the tetramethylbenzidine (TMB) blue reaction process. Five different groups of HRP-labeled vestibular efferent neurons were identified. Three groups were located within the confines of the ipsilateral vestibular nuclear complex (in the lateral, tangential and descending nucleus) and two additional groups, each bilateral, were located in the reticular formation. In 9 additional pigeons, 4,6-diamidino-2-phenylindole (DAPI) was also injected and confined within the endolymphatic space of one labyrinth. DAPI-labeled cells were noted in 3 of the 5 locations (tangential nucleus, and both reticular groups) which in the other animals contained HRP-labeled cells. These findings raise the possibility of different physiological roles for the efferent vestibular groups in the ipsilateral vestibular nuclear complex and bilateral reticular formation.

Animals↗
PubMed2001

GABA and chloride permeate via the same channels across single plasma membranes microdissected from rabbit Deiters' vestibular neurones.

The permeation of labelled gamma-aminobutyric acid (GABA) across single microdissected Deiters' membranes has been studied in a microchamber system. The GABA permeation is via pores which are blocked by 4,4'-diisothiocyanato stilbene-2-2'disulphonic acid (DIDS). As this substance blocks as well chloride permeation across these membranes we tested whether GABA and chloride permeate across the same pores. Membrane pre-treatment with different doses of corticotropin releasing factor (CRF), a membrane permeant cyclic AMP analogue and phalloidin parallelly block the permeation of the two substances. Thus, it is most probable that GABA and chloride pass across the same pores. These pores may be swelling activated ones, opened by the mechanical stress on the membranes in the microchamber system. The passage of GABA across these pores may be of physiological importance in the termination of GABA inhibitory action on the vestibular Deiters' neurones.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

[Study on the origin of vestibular neurons projecting to the spinal cord using retrograde labelling technique of horseradish peroxidase].

In spite of a large number of electrophysiological studies into the vestibulospinal (VS) effects on the spinal cord, there are far fewer anatomical studies on the VS projections. The present study was undertaken to determine the origins and descending pathways of VS neurons in the cat, using a retrograde labelling technique of horseradish peroxidase (HRP) combined with a lesion in the lower brainstem. HRP was applied unilaterally into the cervical or lumbar spinal cord and either the medial longitudinal fasciculus (MLF) or the lower medulla oblongata, sparing the MLF, was dissected. In all cases, HRP-labelled neurons were located in two distinct areas of the vestibular nuclear complex, the rostral and caudal areas. In the rostral area, HRP-labelled neurons after dissection of the MLF appeared in the ipsilateral lateral (LN), medial (MN) and descending nuclei (DN), on the same side as HRP insertion into the spinal cord, but somatotopical arrangement was not seen in the present study. Labelled neurons in the rostral part after impairment of a wide area of the lower medulla, though sparing the MLF, were seen bilaterally in the areas bordering the LN, MN, DN and superior nuclei. In the caudal area, HRP-labelled neurons were seen bilaterally in the caudal thirds of the MN and DN, and these projected to the lumbar spinal cord. Therefore the origins and descending pathways of the VS tracts were considered to be different from those shown in previous anatomical studies.

Animals↗
PubMed1997

Short-term response of postnatal rat vestibular neurons following brain-derived neurotrophic factor or neurotrophin-3 application.

The effects of the application of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) neurotrophins on the intracellular calcium level ([Ca2+]i) were studied in vestibular ganglion neurons (VGNs) from postnatal day 3 (P3) rats cultured for 50 hr. We first assessed the expression of trkB and trkC mRNA receptors in cultured VGNs. Immunobloting and immunocytochemistry confirmed the presence of the neurotrophin receptors on neurons. Both neurotrophins induced transient [Ca2+]i elevations in VGNs: BDNF-treated neurons responded in 65% and NT-3-treated neurons in 56%. The responses could be inhibited by anti-BDNF or anti-NT-3 antibodies. The [Ca2+]i elevation was dependent on extracellular calcium since it was abolished in calcium-free medium but also implicates the release of calcium from intracellular stores as tested by prior depletion with thapsigargin. Our results suggest the implication of a short-term calcium regulation in VGNs, which could reflect specific fast effects of neurotrophins in the early postnatal rat vestibular system.

Animals↗