In anesthetized rats, unilateral injection of l-glutamate (5 nmol) into the medial vestibular nucleus (MVe) and spinal vestibular nucleus (SpVe) slightly increased the mean arterial pressure (MVe: 93.29+/-11.58 to 96.30+/-11.66, SpVe: 91.72+/-15.20 to 95.48+/-17.16). 
The discharge properties of the medial vestibular nucleus neurones (MVNn) critically depend on the activity of several ion channel types.
A vestibular-plus-saccade (VPS) neuron was recorded in the rostral medial vestibular nucleus (rMVN) of a cynomolgus monkey, an area where we postulate that velocity storage is generated.
The involvement of the MLF pathway originating in the medial vestibular nucleus (MVN) in this transmission is experimentally and clinically well established whereas a role of the BC appears to be questionable.
In a model preparation, the decerebrate pigeon, EOM afferent signals modified single unit activity in the medial vestibular nucleus, and the third and sixth motor nuclei, during sinusoidal vestibular stimulation.
Besides, they were differentially expressed in the medial vestibular nucleus, locus coeruleus and the ventral medulla.
Our previous in vivo and in vitro whole-cell patch-clamp recording studies demonstrated that neurons in the medial vestibular nucleus (MVN) could be characterized on the basis of three electrophysiological properties: afterhyperpolarization (AHP) profile; firing pattern; and response pattern to hyperpolarizing current pulses.
In this study, in order to investigate the signaling pathway of glutamate in the vestibular nuclei following acute hypotension, expression of the NR2B subunit of glutamate N-methyl-D-aspartate (NMDA) receptors and the GluR1 subunit of glutamate alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors was measured by Western blotting in the medial vestibular nucleus (MVN) following acute hypotension in bilateral labyrinthectomized (BL) rats.
We investigated the role of the vestibular commissural inhibitory system in vestibular compensation (VC, the behavioural recovery that follows unilateral vestibular loss), using in vivo microdialysis to measure GABA levels in the bilateral medial vestibular nucleus (MVN) at various times after unilateral labyrinthectomy (UL).
Tests with surviving medulla sections of white non-strain male rats showed 100 microM of strychnine (glycine antagonist) but not 20-100 microM GABA-negative biku-kullin and picrotoxin reduced almost double the postsynaptic N1-amplitude of the population response to afferent vestibular stimulation in the ventral region of the medial vestibular nucleus (MVN).
The serotonergic system regulates processing in components of the vestibular nuclear complex, including the medial vestibular nucleus (MVe) and nucleus prepositus hypoglossi (PH).
Cytoarchitectonic differentiation of the vestibular nuclei proceeded over the next 3 to 4 weeks with the emergence of discrete parvicellular and magnocellular components of the medial vestibular nucleus by P19.
Changes in intensity of GAP-43 expression in the medial vestibular nucleus, superior olivary nucleus, and torus semicircularis appeared correlated with stage-dependent functional changes in processing auditory stimuli.
From retrograde injections into the both the flocculus and uvula-nodulus, numerous cells were found in the superior vestibular nucleus (VeS), the cerebellovestibular process (pcv), the descending vestibular nucleus (VeD), and the medial vestibular nucleus (VeM).
Postflight testing revealed (a) delayed onset of body righting responses, (b) cardiac deceleration (bradycardia) to 70 degrees head-up roll, (c) decreased branching of gravistatic afferent axons, but (d) no change in branching of angular acceleration receptor projections with comparable synaptogenesis of the medial vestibular nucleus in flight relative to control fetuses.
The medial vestibular nucleus of mutants ipsilateral to the preferred direction of rotation contained higher M2 densities than the contralateral one.
Virus-infected neurons were revealed mainly in the medial vestibular nucleus.
P2X7-positive neurons were found in the anterior olfactory nucleus, cerebral cortex, piriform cortex (Pir), lateral septal nucleus (LS), hippocampal pyramidal cell layers of CA1, CA3, CA4, pontine nuclei, external cuneate nucleus, and medial vestibular nucleus.
The aim of the present study was to define the distribution of CNG channels in the rat medial vestibular nucleus (MVN) and their possible involvement in regulating MVN neuron (MVNn) excitability.
Electrophysiological studies of medial vestibular nucleus (MVN) neurons, however, show that their response to sinusoidal currents above 10 to 12 Hz is highly nonlinear and distorted by aliasing for all but very small current amplitudes.
Using extracellular recordings and bath application of agonists and antagonists, we compared GABA receptors in the medial vestibular nucleus of brain slices from Scn8a mutant mice of med(J) type, in which there is greatly reduced spontaneous and evoked activity of Purkinje cells, to those in slices from control mice. It may relate in both cases to reduced Purkinje cell input to medial vestibular nucleus neurons.
In our previous study using the whole-cell patch clamp technique combined with reverse transcription-polymerase chain reaction analysis in rat brainstem slices, we demonstrated that the classification of neurons in the medial vestibular nucleus (MVN) based on three membrane properties detected as voltage response properties to depolarizing and hyperpolarizing current pulses, namely afterhyperpolarization (AHP) profiles, firing patterns, and response patterns to hyperpolarizing current pulses, is useful for clarifying the relationship between membrane properties and cellular markers for excitatory and inhibitory neurons.
In juvenile mice, the KCNE1 mutation was associated with a strong decrease in the expression of the calcium-binding proteins calbindin, calretinin and parvalbumin within the medial vestibular nucleus (MVN) and important modifications of the membrane properties of MVN neurons.
By incorporating spike rate adaptation and postinhibitory rebound as observed in medial vestibular nucleus neurons, our model produces realistic anticipation on a large corpus of rat movement data.
We have studied the effect of unilateral labyrinthectomy (UL) on protein levels and expression of GDNF multicomponent receptor complex: the ret tyrosine kinase and coreceptor GFRalpha-1 in the medial vestibular nucleus of the adult rat. GFRalpha-1 protein levels display an increasing trend in ipsilateral medial vestibular nucleus culminating at 48 h post UL. On the other hand, GFRalpha-1 mRNA expression levels in ipsi- and contralateral medial vestibular nucleus show a steadily decreasing trend that is significant at 1 week post-lesion. Protein levels for c-Ret isoforms also show an initial bilateral decreasing trend that ceases at 48 h in ipsilateral medial vestibular nucleus but persists on the contralateral side.
Eighteen hours after microinjection of 5,7-DHT into the DRN, fine-caliber degenerating serotonergic terminals were found within the region of the medial vestibular nucleus (MVN) that borders the fourth ventricle, and a mixture of fine- and heavier-caliber degenerating serotonergic terminals was located further laterally within the vestibular nuclear complex.
Aging affects the volume of the superior and lateral vestibular nuclei, as well as the nuclear neuronal diameter of the medial vestibular nucleus, but no significant neuronal loss has been appreciated in vestibular nuclear complex related with age.
RESULTS: Three types of labeled neurons were observed: (1) neurons only retrogradely microfluorosphere-labeled that were mainly located in the medial vestibular nucleus, lateral vestibular nucleus, superior vestibular nucleus and parvicellular reticular nucleus on the ipsilateral side of the injection; (2) neurons that were both immunolabeled with CGRP and also retrogradedly labeled with microfluorospheres, indicating that they are CGRP cells projecting to the area of vestibular efferent nucleus, these cells were mainly distributed in the superior vestibular nucleus and dorsal vestibular nucleus, and (3) cells only immunolabeled for CGRP that were scattered extensively in the brainstem.
RESULTS: Twenty-four hours after surgery, significantly increased c-Fos positive cells were observed in the bilateral medial vestibular nucleus (MVe), bilateral spinal vestibular nucleus (SpVe), contralateral prepositus hypoglossal nucleus (PrH), and contralateral inferior olive nucleus (IO)..
OBJECTIVE: To establish the visual patch clamp whole-cell recording technique and study the properties and functional significance of muscarinic receptor-mediated currents in rat medial vestibular nucleus neurons (MVNn).
Background impulse activity of the neurons of ipsilateral medial vestibular nucleus of unilaterally delabyrinthined rats was studied on different days after operation as well as after 5-day vibration.
By targeting recordings to neurons labeled in transgenic mouse lines, this study reveals that the continuous distribution of intrinsic parameters observed in medial vestibular nucleus (MVN) neurons can be neatly subdivided into two populations of neurons, one of which is GABAergic and the other of which is exclusively glycinergic or glutamatergic.
To understand the neurochemical mechanisms underlying the vestibular compensation, we determined the levels of amino acids such as aspartate, glutamate, glutamine, glycine, taurine, alanine in the medial vestibular nucleus (MVN) following unilateral labyrinthectomy (UL), by using in vivo brain microdialysis and high-performance liquid chromatography technique.
Throughout larval stages, cells in the medial vestibular nucleus show best frequencies to particle motion in the range from 15 to 65 Hz, with displacement thresholds of <10 mum. Transport of a lipophilic dye from peripheral end organs to the dorsal medulla shows that fibers from the saccule in the inner ear and from the anterior lateral line both terminate in the medial vestibular nucleus.
Recently, experiments using transynaptic retrograde transport of pseudorabies virus provided anatomical evidence that many neurons concentrated in the dorsomedial part of the parvicellular division of the medial vestibular nucleus (MVePC) and the caudal prepositus hypoglossi (PH) provide inputs to motoneurons innervating the lower third of the superficial layer of the masseter muscle.
Here we examined the modulatory effects of histaminergic agents on the release of amino acid neurotransmitters in slices of the medial vestibular nucleus (MVN) prepared from normal and labyrinthectomised rats.
One terminal field was located primarily ipsilateral to the injection site and involved rostrodorsal aspects of the vestibular nuclei, including superior vestibular nucleus and rostral portions of the medial vestibular nucleus (MVN) and lateral vestibular nucleus (LVN).
These include visual input from the dorsolateral pons, and vestibular-oculomotor input from the medial vestibular nucleus (MVe) and the nucleus prepositus hypoglossi (Nph).
At all larval stages, injections into the SON produce anterograde and retrograde label in the medial vestibular nucleus bilaterally.
Purkinje cells of zones 2 and 4 projected to the magnocellular and parvicellular parts of the medial vestibular nucleus, while some also innervated the lateral vestibular nucleus or nucleus prepositus hypoglossi.
By mapping the three-dimensional distribution of Fos-immunoreactive neurons, we found an even distribution of otolith-related neurons within the spinal vestibular nucleus in groups x and y but a clustered distribution in the middle-lateral-ventral part of the medial vestibular nucleus.
Our results indicate that the SG receives direct inputs from the medial vestibular nucleus and projects to elements of the HD cell-related circuitry, providing a massive input to the contralateral dorsal tegmental nucleus and a moderately dense projection to the shell region of the lateral mammillary nucleus.
In order to understand whether some special amino acids in the medial vestibular nucleus (MVN) of rats are involved in the regulation of blood presure, we used microdialysis technique and high performance liquid chromatography (HPLC) to measure the changes of glutamate and taurine in this central area.
Finally, we quantified binding to histamine H3 receptors (H3Rs) in the medial vestibular nucleus (VN) by means of a histamine H3R agonist ([ 3H]N-alpha-methylhistamine) in order to further investigate the sites and mechanisms of action of histamine in this structure.
The behavior of this subset of PHNn, referred to as type D PHNn, is clearly different from that of the medial vestibular nucleus neurons, which transmit the bulk of head velocity-related sensory vestibular inputs without integrating them.
In the present study, we first observed up-regulation in preproenkephalin (PPE)-like immunoreactivity (-LIR), a precursor of Met- and Leu-enkephalin, in the rat ipsilateral medial vestibular nucleus (ipsi-MVN) after unilateral labyrinthectomy (UL).
CB2 immunoreactivity was also observed in olfactory tubercle, islands of Calleja, cerebral cortex, striatum, thalamic nuclei, hippocampus, amygdala, substantia nigra, periaqueductal gray, paratrochlear nucleus, paralemniscal nucleus, red nucleus, pontine nuclei, inferior colliculus and the parvocellular portion of the medial vestibular nucleus.
The amplitudes and slopes of evoked monosynaptic field response (N1) of week-long adapted mice were enhanced around the medial vestibular nucleus compared with those of control mice.
Neurons in the medial vestibular nucleus (MVN) vary in their projection patterns, responses to head movement, and intrinsic firing properties.
OBJECTIVE: To investigate modulation of gamma-aminobutyric acid (GABA) and its receptors on medial vestibular nucleus neurons in vivo. gamma-aminobutyric acid, bicuculine (BIC, gamma-aminobutyric acid A receptor antagonist) and 2-hydroxysaclofen (SAC, gamma-aminobutyric acid B receptor antagonist) were microiontophoreted on medial vestibular nucleus (MVN) neurons to determine the effects of gamma-aminobutyric acid and its antagonists on the neuronal firing rates of medial vestibular nucleus in rats in vivo. CONCLUSIONS: Modulation of gamma-aminobutyric acid on medial vestibular nucleus neurons was mediated by y-aminobutyric acid A receptor in vivo..
Fast inhibitory synaptic transmission in the medial vestibular nucleus (MVN) is mediated by GABA(A) receptors (GABA(A)Rs) and glycine receptors (GlyRs).
Previously we found subdivisions of the cat medial vestibular nucleus (MVe) defined by immunoreactivity to the calcium-binding proteins, calretinin and calbindin.
In experiments with immobilized cats (myorelaxation drugs) the microelectrode technique and microontoiphoresis of physiologically active substances revealed that ethylmethyl hydroxypyrine influences the majority of neurons in the medial vestibular nucleus (61%).
Outside the NTS, HSD2-immunoreactive neurons were found in only two other sites: the ventrolateral division of the ventromedial hypothalamic nucleus and a few scattered neurons in the medial vestibular nucleus, just rostral to the NTS.
Following 72-h survival times, a few transynaptically labeled neurons appeared bilaterally in the medial vestibular nucleus (MVe) and the caudal prepositus hypoglossi (PH) and in the ipsilateral spinal vestibular nucleus (SpVe).
CONCLUSION: The results of this study suggest that neither the number of medial vestibular nucleus (MVN) neurons expressing cytosolic glucocorticoid receptors nor blood corticosterone levels change significantly during the development of vestibular compensation.
Here, we demonstrate the expression of the alpha-subunit of rod- and olfactory-type CNG channels (CNG1 and CNG2, respectively) in the rat medial vestibular nucleus (MVN).
Over recent years, medial vestibular nucleus (MVN) neurons and to a lesser extent other vestibular neurons have been extensively studied in vivo and in vitro, in a range of species.
medial vestibular nucleus neurons develop a sustained increase in electrophysiological excitability after deafferentation, which may be an important component of 'vestibular compensation' (the behavioural recovery that follows peripheral vestibular lesions). We investigated the effects of gamma-aminobutyric acid, glutamate and glycine receptor blockade on the spontaneous activity of deafferented medial vestibular nucleus neurons in slices, to determine whether changes in synaptic inputs contribute to their increased excitability. Soon after deafferentation (4 h after labyrinthectomy) synaptic blockade had no effect on the elevated in-vitro firing of medial vestibular nucleus neurons, while later (48 h, 1 week), synaptic blockade reduced the elevated activity to normal. Intrinsic mechanisms therefore appear to mediate the elevated excitability of medial vestibular nucleus cells initially after deafferentation.
In rats receiving UL we did not find any changes in mitochondrial ultrastructure in the medial vestibular nucleus following UL, and there was no change in the expression or activation of the apoptosis effector caspase-3 in the whole VNC following UL.
Immunocytochemical processing of the hindbrain for the inducible c-fos gene product Fos revealed that 4CIN enhanced Fos immunoreactivity in the dorsal vagal complex (DVC), e.g., the nucleus of the solitary tract and dorsal vagal motor nucleus, and adjacent area postrema, sites where cells characterized by unique sensitivity to diminished glucose and/or glycolytic intermediate/end product levels reside, and in the medial vestibular nucleus (MV), and that CV4 L-lactate infusion increased Fos labeling within the DVC and MV after insulin-induced hypoglycemia.
No lateral canal-related units were found after nerve section, and vertical canal-related units were found only in SVN not in the rostral medial vestibular nucleus.
Both compensated high and low gain adaptation groups displayed increased floccular and IOK Fos labeling, but only compensated high gain adaptation produced increased Fos labeling in the medial vestibular nucleus.
The mammalian medial vestibular nucleus (MVe) receives input from all vestibular endorgans and provides extensive projections to the central nervous system. In this study, afferent and efferent subcortical connectivity of the medial vestibular nucleus of the golden hamster (Mesocricetus auratus) was evaluated using cholera toxin subunit-B (retrograde), Phaseolus vulgaris leucoagglutinin (anterograde), and pseudorabies virus (transneuronal retrograde) tract-tracing techniques.
However, the locus coeruleus and medial vestibular nucleus, which contribute to sleep and eye movement regulation and which send projections to the IGL, do not receive reciprocal projections from it.
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.
In both visual conditions, flocculus and paraflocculus Purkinje cell labeling was also observed, and some of the Fos-labeled cells in the medial vestibular nucleus were commissural.
Changes in the baseline spike activity in the medial vestibular nucleus were studied after exposure to vibration for 5, 10, and 15 days. Statistically significant changes in the major characteristics of neuron activity were seen in the medial vestibular nucleus at different periods of vibration exposure.
Immunoreactivity for calretinin revealed a small, intensely stained region of cell bodies and processes just beneath the fourth ventricle in the medial vestibular nucleus.
Intense Fos expression was seen in the medial vestibular nucleus, paraventricular hypothalamic nucleus, autonomic nuclei in the brain stem in intact rats, but not in rats with vestibular lesion.
In the early stages of vestibular compensation (VC) (the behavioural recovery that follows unilateral vestibular deafferentation), neurons in the medial vestibular nucleus (MVN) on the lesioned side develop a sustained up-regulation of their intrinsic excitability.
However, injections into the parvocellular medial vestibular nucleus (mvp), or Y group, resulted in labeled terminals over both twitch and nontwitch motoneurons.
The effects of nitric oxide (NO) on the discharge rate of medial vestibular nucleus neurons (MVNn) were investigated in rat brainstem slices.
RESULTS: Expression levels for histamine H3 receptor (total) as well as three isoforms which display variable lengths of the third intracellular loop of the receptor were analyzed using in situ hybridization on brain sections containing the rat medial vestibular nucleus after unilateral labyrinthectomy.
To elucidate the effectiveness of the drug in the treatment of vertebrobasilar insufficiency (VBI), we performed an electrophysiological study to examine the effects of ipenoxazone hydrochloride, a glutamate blocker, on hypoxia-induced firing in the medial vestibular nucleus (MVN) neuron, using alpha-chloralose-anesthetized cats.
In previous studies, neurons in the medial vestibular nucleus (MVN) were classified mainly into 2 types according to their intrinsic membrane properties in in vitro slice preparations.
Distinct clusters of IGL-afferent neurons are also located in the medial vestibular nucleus. Vestibular projections to the IGL were confirmed by using anterograde tracer injection into the medial vestibular nucleus. Injection of a retrograde, trans-synaptic, viral tracer into the SCN demonstrated transport to cells as far caudal as the vestibular system and, when combined with IGL injection of CTB, confirmed that some in the medial vestibular nucleus polysynaptically project to the SCN and monosynaptically to the IGL, as do cells in other brain regions.
Because the contralesional labyrinth plays a prominent role in the generation of these dynamic responses, intracellular recordings of contralesional medial vestibular nucleus neurons (MVNn) were done after 1 mo of compensation.
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.
We investigated whether the production of the mRNAs for the auxiliary beta subunits of the Na channels are modulated in deafferented medial vestibular nucleus (MVN) and in axotomized facial motoneurons. No beta1-3 mRNAs modulation was detected at any time following unilateral labyrinthectomy in the deafferented and intact medial vestibular nucleus.
To explore this possibility, the effects of electrical stimulation of the medial vestibular nucleus (MVN) on the firing rates of hippocampal CA1 neurons in the urethane-anesthetized rat were investigated using extracellular single unit recordings.
Colocalization of immunoreactivities for gephyrin and glycine receptor subunits was detected in the dorsal and ventral horns of the spinal cord, the hypoglossal nucleus and the medial vestibular nucleus of the medulla.
We investigated the changes in glutamate release from the ipsi- and contra-lesional medial vestibular nucleus (MVN) following unilateral labyrinthectomy (UL) by in vivo microdialysis study.
A moderate density is detected in the ventral cochlear and the medial vestibular nucleus.
Principle brainstem areas of termination of the utricular nerve were the lateral/dorsal medial vestibular nucleus, ventral and lateral portions of the superior vestibular nucleus, and rostral portion of the spinal vestibular nucleus.
In the current study, we found that the ratio of medial vestibular nucleus (MVN) neurones endowed with one of the currents known to play a role in pacemaker activity (i.e.
The method of computer analyses was used for the research of the spectral changes of spontaneous neuronal activity of the medial vestibular nucleus ander vibration action (5, 10 and 15 daily).
Spontaneous synaptic currents of medial vestibular nucleus (MVN) neurons were studied using whole cell recording in slices prepared from 13- to 17-day-old rats.
Some labeling was also found in the dorsal VeS and the dorsolateral margin of the caudal descending vestibular nucleus, and a small amount of labeling was found laterally in the caudal margin of the medial vestibular nucleus.
To determine whether changes were limited to the PBC, the present study aimed at examining the expression of CO in a number of brain stem nuclei, with or without known respiratory functions from P0 to P21 in rats: the ventrolateral subnucleus of the solitary tract nucleus, nucleus ambiguus, hypoglossal nucleus, nucleus raphe obscurus, dorsal motor nucleus of the vagus nerve, medial accessory olivary nucleus, spinal nucleus of the trigeminal nerve, and medial vestibular nucleus (MVe).
The density of serotonin transporter-immunopositive fibers is greatest in the superior vestibular nucleus and the medial vestibular nucleus, especially along the border of the fourth ventricle; it declines in more lateral and caudal regions of the vestibular nuclear complex.
Little is known, however, about the intrinsic cellular properties of FTNs, which are sparsely distributed in the medial vestibular nucleus. Fluorescent Purkinje cell axons and terminal boutons surrounded the somata and proximal dendrites of a small subset of neurons, presumed FTNs, in the medial vestibular nucleus.
In vitro intracellular recordings of central vestibular neurons have been restricted so far to the medial vestibular nucleus (MVN).
Such terminals were also found in the four main vestibular nuclei, except for the medial vestibular nucleus, where no labeled terminals could be detected.
We previously demonstrated in rat brainstem slices that high-frequency stimulation (HFS) of the vestibular afferents induces long-term potentiation (LTP) in the ventral part (Vp) of the medial vestibular nucleus (MVN) and long-term depression (LTD) in the dorsal part (Dp).
The present study evaluated the effects of melatonin on the discharge rate of tonically active medial vestibular nucleus (MVN) neurons in an in vitro slice preparation of the rat dorsal brainstem.
In the brainstem of normal rats subjected to OVAR, a high density of Fos-immunoreactive (Fos-ir) neurons was found in the vestibular nuclear complex (namely, spinal vestibular nucleus, SpVe; medial vestibular nucleus, Mve; superior vestibular nucleus, SuVe) and subnuclei (namely, group x and group y), whereas a lower density was found in the lateral vestibular nucleus (LVe).
We argue that BT neurons in the nucleus prepositus hypoglossi/medial vestibular nucleus play an important role in the generation of unequal eye movements during disjunctive saccades, and carry appropriate information to shape the saccadic discharges of the abducens nucleus neurons to which they project..
We compared the responses of type A and type B medial vestibular nucleus neurons identified in vitro to current steps and ramps and to sinusoidal currents of various frequencies. Many of the static and dynamic membrane properties of type B neurons became more similar to those of type A neurons than in control slices, leading to an increase in the overall homogeneity of medial vestibular nucleus neurons..
Using in situ hybridization, we found PR mRNA-containing cells widely distributed throughout the brainstem of ovariectomized, estradiol-treated Sprague-Dawley rats, with high expression in regions including the medial vestibular nucleus, nucleus of the solitary tract, substantia nigra (compact part), ventral tegmental area, hypoglossal nucleus, locus coeruleus, Purkinje cell layer of the cerebellum and inferior olivary complex.
The slow-phase network consisted of ganglion and medial vestibular nucleus (MVN) neurons; the latter were constructed using biophysical models of MVN type A and B neurons.
This study is a first step in an attempt to identify the factors which determine and maintain the electrophysiological phenotype(s) of mature neurons of the medial vestibular nucleus (MVN).
The cFos-like immunoreactive (cFLI) neurons were expressed selectively in the central area of the medial vestibular nucleus following a 10% reduction in blood pressure.
First, in the cases that WGA-HRP were injected into the rostral part of medial vestibular nucleus (VN), a significant number of retrograde-labeled neurons, which concentrated between 600 and 800 micrometer from the rostral part of the NOT, were observed in the NOT ipsilateral to the injection sites.
RESULT: 20 h post-unilateral labyrinthectomy, the NMDA R1mRNA positive neurons in the medial vestibular nucleus increased significantly compared with the unlesioned side(P < 0.01). CONCLUSION: The changing trend of the expression of NMDA R1mRNA in the medial vestibular nucleus is related to the recovery of the vestibular static symptoms after unilateral labyrinthectomy.
Extracellular single unit recordings were made from regularly discharging medial vestibular nucleus neurons in brain slices from control rats and from rats surviving 7 days after bilateral transection of the inferior cerebellar peduncle. The data suggest that the decreases of endogenous GABA levels in the medial vestibular nucleus after inferior cerebellar peduncle transection are accompanied by up-regulation of GABA(A) and, to a lesser extent, GABA(B) receptors..
From these, maximal Fos-inhibition by dexamethasone was recognized in the medial vestibular nucleus, however, even in this case the number of suppressed cells did not exceed 50%.
We investigated the role of the cerebellar flocculus in mediating the adaptive changes that occur in the intrinsic properties of brainstem medial vestibular nucleus (MVN) neurons during vestibular compensation.
An unbiased stereological method was used to assess the effect of aging on the number of neurons in the human medial vestibular nucleus. On average, we found 151.10(3) (CV = 0.15) neurons in the medial vestibular nucleus, which is 18% more than that in the prior study.
Twelve of 27 commissural neurons were located in the medial vestibular nucleus, 5 were in the lateral vestibular nucleus, 10 were in the descending vestibular nucleus, and no commissural neurons were recorded in the superior vestibular nucleus.
There was a significant difference in c-Fos expression between the right and left medial vestibular nuclei, and the number of c-Fos-labeled neurons in the medial vestibular nucleus was markedly increased on the opposite side of the rotational direction.
Simultaneous BL did not show any Fos expression in the medial vestibular nucleus (MVe).
For this purpose, we studied the firing rate responses of neurons of the medial vestibular nucleus in brain stem slices to intracellularly injected currents. We conclude that although labyrinthectomy induces some plastic changes in the excitability of the neurons of the medial vestibular nucleus, these changes do not underlie the restoration of activity which occurs in these neurons when they are deprived of their labyrinthine input..
The pattern of FRA protein expression was generally similar to that of Fos, except at 1 day after landing, when FRA-expressing cells were observed throughout the whole spinal vestibular nucleus, but only in the caudal part of the medial vestibular nucleus. Fos expression was found throughout the entire medial vestibular nucleus at this time.
It is possible that these properties depend on the synaptic drives generated by the major premotor inputs to AbMNs, namely position-vestibular-pause (PVP) cells and eye and head velocity (EHV) cells in the medial vestibular nucleus, and eye-position and burst-position cells in the nucleus prepositus hypoglossi (NPH).
The medial vestibular nucleus (MVN) neurons were classified in 8 types (alpha-theta) according to the patterns in response to the clockwise and counterclockwise tilt-stimulations.
In order to investigate the mechanisms responsible for adaptation to altered gravity, we assessed the changes in mRNA expression of glutamate receptors in vestibular ganglion cells, medial vestibular nucleus, spinal vestibular nucleus/lateral vestibular nucleus, cerebellar flocculus, and uvula/nodulus from rats exposed to hypergravity for 2 h to 1 week using real-time quantitative RT-PCR methods. The mRNA expression of GluR2 and NR1 receptors in the uvula/nodulus and NR1 receptors in the medial vestibular nucleus increased in animals exposed to 2 h of hypergravity, and it decreased gradually to the control level.
Moreover, effects of electrical stimulation were identified in the medial vestibular nucleus and the lateral parabrachial nucleus.
While we confirm and extend many previous findings, we also describe a novel segregation of saccular and posterior crista fibers in the anterior half of the medial vestibular nucleus (Mv) not reported before.
The function of the 5-hydroxytryptamine (5-HT) system in the medial vestibular nucleus (MVN) was evaluated using KCl-evoked 5-HT release assessed by in vivo microdialysis.
The density of spontaneously active neurons was highest in the medial vestibular nucleus (MVN), slightly lower in the superior (SuVN) and spinal (SpVN) nuclei, and lowest in the lateral vestibular nucleus (LVN).
Within the circuitry for the vestibuloocular reflex (VOR), neurons in the medial vestibular nucleus (MVN) show adaptive changes in firing rate responses that are correlated with VOR gain (the ratio of evoked eye velocity to input head velocity).
GABAergic neurons projecting to the PH nucleus and containing NO-sensitive cGMP were found almost exclusively in the ipsilateral medial vestibular nucleus and marginal zone. The results suggest that the nitrergic PH neurons control their own firing rate by a NO-mediated facilitation of GABAergic afferents from the ipsilateral medial vestibular nucleus.
In this study we show that, independent of the nature of inputs, the intrinsic membrane properties of neurons in the medial vestibular nucleus substantially influence firing response dynamics.
The majority of both types of neurons were localized in the lateral vestibular nucleus (58.6%), to the lesser extent in the descending vestibular nucleus (30.7%) and very little in the medial vestibular nucleus (10.6%).
A higher GABAergic tone was found in old rats, as indicated by higher benzodiazepine receptor density in lateral vestibular nucleus and higher mRNA level for glutamic acid decarboxylase in cerebral cortex and medial vestibular nucleus.
UT-activated vestibulothalamic neurons were recorded in the medial vestibular nucleus (MVN; 24/40), the lateral vestibular nucleus (LVN; 9/40), the descending vestibular nucleus (DVN; 6/40), and the superior vestibular nucleus (SVN; 1/40).
The tonic discharge of rat medial vestibular nucleus (MVN) neurons, and their responsiveness to GABA receptor agonists were investigated in slices prepared from aged rats (24 months old).
In the magnocellular part (MVmc) of the medial vestibular nucleus (MV), they were seen near the parvocellular part (MVpc) of the MV at caudal levels.
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.
In order to assess the degree to which this transformation is evident in vestibular nucleus neurons of alert cats, we recorded the extracellular discharge properties of 138 second-order vestibular neurons in the superior and medial vestibular nucleus, including 64 neurons identified as second-order vestibulo-ocular neurons by antidromic responses to oculomotor nucleus stimulation and short-latency orthodromic responses to labyrinth stimulation (1.3 ms or less).
In contrast, no abnormal neuronal morphology was seen in the vestibular nuclei, but a significantly reduced neuronal density was found in the medial 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.
Most of the convergent neurons were located in the lateral, the rostral part of the descending and medial vestibular nucleus.
There were no significant differences observed in the pattern or density of Hsp70 accumulation between the young and old rats at 6 h post-HPM exposure, with the exception of the medial vestibular nucleus, which demonstrated significantly greater Hsp70 accumulation in the old rats.
An electrophysiological study was performed using chloral hydrate-anesthetized rats to determine whether tandospirone, a 5-HT1A agonist, affects neuronal activities of the medial vestibular nucleus (MVN), since serotonergic innervation and 5-HT1A receptors are present in this nucleus.
Two synergistic plastic mechanisms have recently been identified in rat medial vestibular nucleus (MVN) neurons during 'vestibular compensation', the behavioral recovery that follows damage to the vestibular receptors or nerve of one inner ear.
The left medial vestibular nucleus (MVN) was explored in a very systematic way and strict methodological precautions were taken in order to validate comparisons between the numbers of spontaneously active neurons recorded in the MVN of distinct slices.
The majority of both types of neurons were localized in the lateral vestibular nucleus (58.6%), to a lesser extent in the descending vestibular nucleus (30.7%) and very little in the medial vestibular nucleus (10.6%).
Some of the cGMP-positive neurons in the marginal zone and medial vestibular nucleus projected to the PH nucleus, predominantly to the ipsilateral side.
Using in situ hybridization with DIG (digoxigenin)-labeled GAP-43 cDNA probe, changes of GAP-43 mRNA expression in the medial vestibular nucleus in the labyrinthectomized rats at 5, 12, 20 and 30th day after operation were investigated.
The effects of a selective decrease in the strength of commissural inhibitory input to the ipsi-lesional medial vestibular nucleus (MVN) neurones, without changes in other parts of the network, were investigated.
Neurons in the medial vestibular nucleus (MVN) participate in the VOR and OKR by firing in response to both head and image motion.
We found that BDNF mRNA is differentially induced in the medial vestibular nucleus ipsilateral to UL and in the prepositus hypoglossi and inferior olive on the contralateral side.
We investigated changes in intrinsic excitability and GABA receptor efficacy in rat medial vestibular nucleus (MVN) neurons following 48 h and 7-10 days of behavioral recovery after unilateral labyrinthectomy (UL) in the rat.
Potassium currents in the isolated medial vestibular nucleus were inhibited by nitric oxide liberating agents, sodium nitroprusside and S-nitroso-N-acetylpenicillamine.
In this study, the effect of acetyl-DL-leucine on the activity of central vestibular neurons of the medial vestibular nucleus (MVN) and/or the overall activity of vestibular-related networks was electrophysiologically measured in brainstem slices and in the isolated, in vitro whole brain (IWB) of guinea-pig.
In the present study, we examined the effects of bath application of vasopressin and noradrenaline on the spontaneous tonic discharge of medial vestibular nucleus (MVN) neurones and investigated if there is an interaction between the two drugs in an in vitro slice preparation of the rat brainstem containing the MVN.
For horizontal gaze, neurons in the nucleus prepositus hypoglossi-medial vestibular nucleus region (NPH-MVN) play a vital role in this neural integrator function.
The tracer substances were injected into the spinal vestibular nucleus (SpVe), the caudal part of the medial vestibular nucleus (MVe), and nucleus X of Brown Norwegian rats.
Fos expression occurred in the medial vestibular nucleus contralateral to the UL side (contra-MVe) and the prepositus hypoglossal nucleus ipsilateral to the UL side (ipsi-PrH), whereas Fos expression was never seen after UL in floccular-intact rats.
In brainstem slices of guinea pigs perfused with artificial cerebro-spinal fluid (ACSF), the discharge of all the spontaneously active neurons of the medial vestibular nucleus (MVN) is regular.
Several motor nuclei, i.e., the vagal motor complex, or sensory nuclei, i.e., the medial vestibular nucleus, show cytoarchitectonic limits that coincide with pseudorhombomeric ones; however, most conventional grisea were found to originate across several pseudorhombomeres.
In rat, dense staining for the P2X receptors was found in the nucleus of the solitary tract (NTS), medial vestibular nucleus, and medial and lateral parabrachial nuclei. In marmoset, prominent P2X receptor-like immunoreactivity occurred in the NTS, medial cuneate nucleus, prepositus hypoglossi, and medial vestibular nucleus.
Analysis of NOS activity in the pre-UVD L-NAME treatment groups at 50 h post-UVD showed that only 100 mM L-NAME resulted in a significant decrease in NOS activity in the contralateral medial vestibular nucleus (MVN)/prepositus hypoglossi (PH) (P<0.05) and that NOS activity in the ipsilateral MVN/PH was not significantly affected.
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.
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.
Survey of the four major vestibular nuclei revealed that only the medial vestibular nucleus contained significant numbers of perikarya stained for NADPH-d/NOS.
The aim of the present study was to compare in vitro protein expression, protein kinase activity and protein phosphorylation in the medial vestibular nucleus (MVN) and prepositus hypoglossi (PH) from labyrinthine-intact guinea pigs and from guinea pigs at various stages of vestibular compensation following unilateral labyrinthectomy (UL).
We observed by anterograde and retrograde tracing techniques that projection fibers originating from the medial vestibular nucleus (MVe) of the rat terminated in the dorsal two-thirds of the lateral part of the parafascicular thalamic nucleus (PF), where neurons sending their axons to the dorsolateral part of the striatum existed.
A leftward-rightward asymmetric modification of the dynamic responses of simulated medial vestibular nucleus type IA neurons on one side, or of type 2 neurons on the other side, to peripheral input would generate an isolated caloric DP. CONCLUSIONS: An isolated caloric DP can be simulated by a neural network model by modifying the activity of model units that represent medial vestibular nucleus neurons.
In a relapsing-remitting peripheral vestibular disorder such as benign paroxysmal positioning vertigo or Ménière's disease, the mechanism of an isolated DP could be enhanced dynamic gain of ipsilesional medial vestibular nucleus neurons, perhaps as a result of intermittent hyperfunction of primary semicircular canal vestibular afferents. The authors postulate that an isolated DP reflects a gain asymmetry between neurons in the medial vestibular nucleus on either side, caused either by increased sensitivity on one side or by reduced sensitivity on the other, perhaps as an adaptive change in response to abnormal input. In an accompanying article, the authors implement a realistic neural network model in which it is possible to simulate an isolated DP by adjusting the dynamic sensitivity of type 1 medial vestibular nucleus neurons on one side or of type 2 medial vestibular nucleus neurons on the other..
Histamine has an excitatory action on rat medial vestibular nucleus neurones in vitro, an effect that is mediated by histamine H1 and H2 receptors. Betahistine, which is a weak agonist at the H1 receptor and a moderate antagonist at the presynaptic H3 autoreceptor, weakly excites medial vestibular nucleus cells but antagonizes their responses to histamine. Experiments were carried out on rat medial vestibular nucleus cells in vitro using slices prepared from animals that had undergone unilateral labyrinthectomy (UL). There was a significant increase in the intrinsic excitability of medial vestibular nucleus cells in the rostral region of the ipsi-lesional nucleus within 4 h post-UL, which was sustained for the following week. These changes in intrinsic excitability of the medial vestibular nucleus neurones were abolished in animals that were not exposed to the secretion of stress hormones that normally occurs following UL.
We therefore compared the sensitivity of medial vestibular nucleus neurones to glycine and muscimol in slices taken either from control animals, or from guinea-pigs labyrinthectomized 3 days before.
Labeled terminals of Purkinje cell axons were numerous in the superior vestibular nucleus, the parvocellular (MVpc) and the caudal part (MVc) of the medial vestibular nucleus (MV), and group y.
The inhibitory effects of the GABAA agonist muscimol and the GABAB agonist baclofen on tonically active medial vestibular nucleus (MVN) neurones were recorded in slices of the rat dorsal brainstem in vitro, to determine whether any changes occurred in the functional efficacy of GABAergic inhibition in these cells during the initial rapid stage of 'vestibular compensation', the behavioural recovery that takes place after unilateral labyrinthectomy (UL).
A medial descending noradrenergic bundle (MDB) projects from LC to LVN, the medial vestibular nucleus (MVN), group y and rostral nucleus prepositus hypoglossi (rNPH).
The responses of the medial vestibular nucleus (MVN) neurons to lateral tilt and the neurotransmitters mediating otolith information to MVN neurons were investigated using rats.
Light terminal labeling was observed in the dorsolateral vestibular nucleus, the medial vestibular nucleus, the tangential nucleus, and the lateral vestibular nucleus pars ventralis. Injections into the rotation zone resulted in heavy terminal labeling in the superior vestibular nucleus (particularly dorsally and medially), the descending vestibular nucleus (particularly medially), and the medial vestibular nucleus.
An imbalance between the resting activities of medial vestibular nucleus neurons on both sides of the brainstem was revealed in brains taken more than three days after the lesion: their discharge was higher on the compensated, initially lesioned side than on the newly deafferented side. Brains taken from compensated animals displayed a significant, bilateral decrease of the inhibitory commissural responses evoked in the medial vestibular nucleus by single-shock stimulation of the contralateral vestibular nerve.
The use of multiple versions of the basic network, trained to simulate individual guinea pigs, highlighted the importance of the particular connections: the vestibular ganglion to the type I medial vestibular nucleus (MVN) cells on the contralesional side.
The ultrastructural characteristics of non-degenerating GABAergic neurons in rostrolateral medial vestibular nucleus were identified in monkeys following midline transection of vestibular commissural fibers. In the previous papers, we reported that most degenerated cells and terminals in this tissue were located in rostrolateral medial vestibular nucleus, and that many of these neurons were GABA-immunoreactive. In the present study, we examined the ultrastructural features of the remaining neuronal elements in this medial vestibular nucleus region, in order to identify and characterize the GABAergic cells that are not directly involved in the vestibular commissural pathway related to the velocity storage mechanism. On the basis of ultrastructural observations of immunostained tissue, we conclude that at least two types of GABAergic neurons are present in the rostrolateral portion of the monkey medial vestibular nucleus: neurons related to the velocity storage pathway, and a class of vestibular interneurons. We hypothesize that "Type A" boutons correspond to Purkinje cell afferents in rostrolateral medial vestibular nucleus, "Type B" terminals represent the axons of GABAergic medial vestibular nucleus interneurons, and "Type C" boutons take origin from vestibular commissural neurons of the velocity storage pathway..
We concluded that at least some of the commissural axons mediating velocity storage originate from clusters of neurons in the lateral crescents of the rostral medial vestibular nucleus. The observation of GABAergic axoaxonic synapses in this pathway is interpreted as a structural basis for presynaptic inhibition of medial vestibular nucleus circuits by velocity storage-related commissural neurons.
The purpose of the present study was to identify the ultrastructural characteristics of commissural neurons in the medial vestibular nucleus that are related to the velocity storage component of the angular vestibulo-ocular reflex. Ultrastructural studies of degenerating medial vestibular nucleus neurons were conducted in monkeys following midline section of rostral medullary commissural fibers with subsequent behavioral testing. Ultrastructural observations indicate that commissural neurons related to velocity storage are small and medium sized cells having large nuclei with deep indentations and relatively little cytoplasm, which are located in the lateral crescents of rostral medial vestibular nucleus. The commissural nature of these cells was further suggested by the presence of two different types of degenerating axon terminals in the rostral medial vestibular nucleus: those with a moderate density of large spherical synaptic vesicles, and those with pleomorphic, primarily ellipsoid synaptic vesicles.
Within that network, most of the second-order neurons of the medial vestibular nucleus (MVNn) compute internal representations of head movement velocity in the horizontal plane.
In acute rat experiments the technique of retrograde axonal transport of horseradish peroxidase in the medial vestibular nucleus allowed to identify a group of neurones sending axons to the "stomach" region of a single tract nucleus.
A unilateral microinjection of either histamine or kainic acid was made into the medial vestibular nucleus of rats, eliciting robust barrel rotations that were evaluated by an elevated body-rotation test.
The AChE reactivity also shows that the medial vestibular nucleus extends more rostrally than previously described.
We have recently shown that neurones in the rostral region of the medial vestibular nucleus (MVN) develop a sustained increase in their intrinsic excitability within 4 h of a lesion of the vestibular receptors of the ipsilateral inner ear.
Medullary Fos-like immunoreactivity observed in the 'Stimulated' and 'Unstimulated' groups exceeded levels observed in untreated rats and was detected in the rostral, caudal and intermediate areas of the ventrolateral medulla, and the commissural, intermediate, medial and lateral regions of the solitary tract nucleus, as well as the medial vestibular nucleus, and the dorsal motor nucleus of the vagus.
The results showed that the superior vestibular nucleus and the medial vestibular nucleus, especially its rostral-to-middle parts, project to the lateral part of the parafascicular thalamic nucleus (corresponding to the centromedian nucleus in primates), the transitional zone between the ventrolateral thalamic nucleus (VL) and the ventral posterolateral thalamic nucleus (VPL) (the region considered to be the nucleus ventralis intermedius of Vogt [ Vogt C.
The effects of nociceptin (orphanin FQ) on medial vestibular nucleus (MVN) neurons in vitro, and on vestibulo-ocular reflex (VOR) function in vivo, were investigated in order to determine the role of 'opioid-like orphan' (ORL1) receptors in modulating vestibular reflex function in the rat.
Vestibular compensation consists of two stages: the inhibition of the contralesional medial vestibular nucleus (contra-MVe) activities at the acute stage after unilateral labyrinthectomy (UL) and the recovery and maintenance of the ipsilesional MVe (ipsi-MVe) spontaneous activities at the chronic stage after UL.
The medial aspect of the NIA receives afferents from the lateral reticular nucleus, external cuneate nucleus, perihypoglossal nucleus, medial vestibular nucleus and inferior central raphe nucleus.
Extracellular and whole-cell patch clamp intracellular recordings were made from rat medial vestibular nucleus (MVN) neurones in vitro, and their responses to selective mu-, kappa- and delta-opioid receptor agonists and antagonists were examined.
The medial vestibular nucleus (MVN) is the largest nucleus of the vestibular nuclear complex, and it seems to be related mainly to vestibular compensation and vestibulo-ocular reflexes.
Effects of ethanol on acutely dissociated medial vestibular nucleus (MVN) neurons were examined using whole-cell patch clamp technique to elucidate the mechanism underling the inhibitory effects of this drug on the neurons observed in in vivo studies.
After microinjection of a horseradish peroxidase solution in the 'gastric' area of the nucleus tractus solitarius, retrogradely-labelled cell bodies were found in caudal part of the medial vestibular nucleus.
Furthermore, enhanced 2-DG uptake was found in the ventromedial, ventrolateral, and anteroventral nuclei of the thalamus (19-42%) and in the medial vestibular nucleus (23%).
vertebrobasilar insufficiency; VBI), an electrophysiological study was performed to examine the effects of a unilateral vertebral artery (VA) occlusion on the neuronal activities of the medial vestibular nucleus (MVN) and vestibular ganglion (VG) in alpha-chloralose-anesthetized cats.
To examine the relationship between neurosteroids and vertigo we performed electrophysiological studies to determine whether pregnenolone sulfate (PS) affects the activity of medial vestibular nucleus (MVN) neurons in alpha-chloralose-anesthetized cats.
We investigated the effects of the selective CB1 receptor agonist, CP 55940 (the levorotatory enantiomer of desacetyllevonantradol), on medial vestibular nucleus neurons in guinea pig brainstem slices in vitro. Only 3/18 medial vestibular nucleus neurons tested with 1 microM CP 55940 showed changes in firing rate, however these were decreases with an average magnitude of 72.3%; 3/4 neurons tested with 10 microM CP 55940 showed decreases with an average magnitude of 92.7% (P < 0.05 in both cases).
The aim of this study was to investigate the effects of systemic administration of dexamethasone on vestibular compensation of spontaneous nystagmus (SN) in guinea pig, and the effects of dexamethasone and methylprednisolone on extracellularly recorded spontaneous activity of medial vestibular nucleus (MVN) neurons in brainstem slices in vitro.
An electrophysiological investigation was undertaken to determine whether dehydroepiandrosterone sulfate (DHEAS), a neurosteroid, influences the neuronal activity of medial vestibular nucleus (MVN) neurons in alpha-chloralose-anesthetized cats.
The postnatal maturation of medial vestibular nucleus (MVN) neurones was examined in slices of the dorsal brainstem prepared from balb/c mice at specific stages during the first postnatal month.
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