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PubMed1982

[Quantitative morphologic examination of the vesicle population of mixed synapses--method and significance].

Quantitative electron microscopic investigations have been performed regarding the population of clear round vesicles within the axosomatic mixed contacts between secondary vestibular and oculomotor neurons of the trout. The measurements are based on a subdivision of the axon terminal area into single fields which topographically belong to different synaptic types (active zone, gap junction) of this mixed contact. Furthermore, areas between active zones and gap junctions ("intermediate zones") and areas along the lateral membranes of the axon terminal ("border zones") have been analyzed. The following vesicle parameters have been estimated stereologically: volume density (Vvv), surface density (Svv), numerical vesicle density (Nvv) mean vesicle volume (Vv) and mean vesicle surface (Sv). In this connection, aspects of the homogeneous distribution, of number and size of the organelles hae been investigated. The results obtained show a characteristic distribution in number and size of vesicles inthe presynaptic areas of the different membrane specializations of this mixed synapses. The results further indicate that two different pools of clear round vesicles exist in this mixed synapse, clear synaptic vesicles for chemical transmission and gap junction vesicles. In relation to the synaptic vesicles, a recycling mechanism is suggested. Gap-junction vesicles may function as Ca++ transport organelles to regulate gap junction permeability. A possible role in trophic tasks of the gap junction is also discussed.

Animals↗
PubMed1993

Temporal response properties of lumbar-projecting vestibulospinal neurons to roll tilt in decerebrate cats.

In decerebrate cats, rotation about the longitudinal axis of the animal, leading to sinusoidal stimulation of labyrinth receptors, produces a tonic contraction of limb extensors during side-down tilt (alpha responses) and of dorsal neck extensors during side-up tilt (beta responses). These changes in posture are mediated, at least in part, by lateral vestibular nucleus (LVN) neurons, with response characteristics to stimulation of macular and/or canal receptors that have so far been evaluated at the level of either unidentified vestibulospinal (VS) neurons or vestibulo-collic neurons projecting to the upper cervical cord. In the present study we investigated the dynamics of the responses of VS neurons projecting to the lumbosacral segments of the spinal cord to increasing frequencies of tilt (from 0.026 to 0.32 Hz, +/- 10 degrees). All the recorded units showed an average phase lead with respect to position of +25.6 +/- 5.5 degrees (SE) at the tilt frequency of 0.026 Hz. Most of these neurons (n = 32) were particularly activated during side-down tilt (alpha responses) and showed either a stable phase or an increase in phase lead of the responses with increasing frequency of tilt. At the tilt frequency of 0.026 Hz, the smaller the phase lead of the responses, the larger was the response gain. Moreover, the smaller the phase lead of the responses at that frequency of tilt, the smaller the increase in gain but the larger was the increase in lead of the responses obtained by increasing the stimulation frequency up to 0.32 Hz. Through this set of finely organized changes in unit response characteristics, the overall output of this population of neurons increased, while the phase angle of the responses reached the mean value of +64.9 +/- 2.6 degrees (SE), thus becoming more related to the velocity than to the positional signal. The remaining units (n = 7), which were mainly activated during side-up tilt (beta responses), displayed an increase in phase lag of the responses to increasing frequency of stimulation, which reached the mean value of -118.9 +/- 14.5 degrees (SE) at 0.32 Hz. The differences in the dynamic properties of these VS neurons projecting to the lumbosacral cord, with respect to those of previously recorded populations of VS neurons, are discussed.

Animals↗
PubMed2006

The vestibular-related frontal cortex and its role in smooth-pursuit eye movements and vestibular-pursuit interactions.

In order to see clearly when a target is moving slowly, primates with high acuity foveae use smooth-pursuit and vergence eye movements. The former rotates both eyes in the same direction to track target motion in frontal planes, while the latter rotates left and right eyes in opposite directions to track target motion in depth. Together, these two systems pursue targets precisely and maintain their images on the foveae of both eyes. During head movements, both systems must interact with the vestibular system to minimize slip of the retinal images. The primate frontal cortex contains two pursuit-related areas; the caudal part of the frontal eye fields (FEF) and supplementary eye fields (SEF). Evoked potential studies have demonstrated vestibular projections to both areas and pursuit neurons in both areas respond to vestibular stimulation. The majority of FEF pursuit neurons code parameters of pursuit such as pursuit and vergence eye velocity, gaze velocity, and retinal image motion for target velocity in frontal and depth planes. Moreover, vestibular inputs contribute to the predictive pursuit responses of FEF neurons. In contrast, the majority of SEF pursuit neurons do not code pursuit metrics and many SEF neurons are reported to be active in more complex tasks. These results suggest that FEF- and SEF-pursuit neurons are involved in different aspects of vestibular-pursuit interactions and that eye velocity coding of SEF pursuit neurons is specialized for the task condition.

Animals↗
PubMed1997

Excitatory and inhibitory vestibular pathways to the extraocular motor nuclei in goldfish.

Electrophysiological, ultrastructural, and immunohistochemical techniques were utilized to describe the excitatory and inhibitory vestibular innervation of extraocular motor nuclei in the goldfish. In antidromically activated oculomotor motoneurons, electrical stimulation of the intact contralateral vestibular nerve produced short-latency, variable amplitude electrotonic excitatory postsynaptic potentials (EPSPs) at 0.5-0.7 ms followed by chemical EPSPs at 1.0-1.3 ms. Stimulation of the ipsilateral vestibular nerve produced small amplitude membrane hyperpolarizations at a latency of 1.3-1.7 ms in which equilibrium potentials were slightly more negative than resting potentials. The inhibitory postsynaptic potentials (IPSPs) reversed with large amplitudes after the injection of chloride ions suggesting a proximal soma-dendritic location of terminals exhibiting high efficacy inhibitory synaptic conductances. In antidromically identified abducens motoneurons and putative internuclear neurons, electrical stimulation of the contralateral vestibular nerve produced large-amplitude, short-latency electrotonic EPSPs at 0.5 ms followed by chemical depolarizations at 1.2-1.3 ms. Stimulation of the ipsilateral vestibular nerve evoked IPSPs at 1.4 ms that were reversed after injection of current and/or chloride ions. gamma-Aminobutyric acid (GABA) antibodies labeled inhibitory neurons in vestibular subdivisions with axons projecting into the ipsilateral medial longitudinal fasciculus (MLF). Putative GABAergic terminals surrounded oculomotor, but not abducens, motoneurons retrogradely labeled with horseradish peroxidase. Hence the spatial distribution of GABAergic neurons and terminals appears highly similar in the vestibuloocular system of goldfish and mammals. Electron microscopy of motoneurons in the oculomotor and abducens nucleus showed axosomatic and axodendritic synaptic endings containing spheroidal synaptic vesicles establishing chemical, presumed excitatory, synaptic contacts with asymmetric pre- and/or postsynaptic membrane specializations. The majority of contacts with spheroidal vesicles displayed gap junctions in which the chemical and electrotonic synapses were either en face to dissimilar or adjacent to one another on the same soma/dendritic profiles. Another separate set of axosomatic synaptic endings, presumed to be inhibitory, contained pleiomorphic synaptic vesicles with symmetric pre- and/or postsynaptic membrane specializations that never included gap junctions. Excitatory and inhibitory synaptic contacts appeared equal in number but were more sparsely distributed along the soma-dendritic profiles of oculomotor as compared with abducens motoneurons. Collectively these data provide evidence for both disynaptic vestibular inhibition and excitation in all subdivisions of the extraocular motor nuclei suggesting the basic vestibulooculomotor blueprint to be conserved among vertebrates. We propose that unique vestibular neurons, transmitters, pathways, and synaptic arborizations are homologous structural traits that have been essentially preserved throughout vertebrate phylogeny by a shared developmental plan.

Abducens Nerve↗
PubMed1990

Distribution of messenger RNAs encoding the enzymes glutaminase, aspartate aminotransferase and glutamic acid decarboxylase in rat brain.

In situ hybridization histochemistry (ISHH) using synthetic oligonucleotide probes has been used to identify cells containing the mRNAs coding for glutaminase (GluT), aspartate aminotransferase (AspT) and glutamic acid decarboxylase (GAD). The distribution of GAD mRNA confirms previous descriptions and matches the distribution of GAD detected using specific antibodies. AspT mRNA is widely distributed in the brain, but is present at high levels in GABAergic neuronal populations, some that may be glutamatergic, and in a subset of neurons which do not contain significant levels of either GAD or GluT mRNA. Particularly prominent are the neurons of the magnocellular division of the red nucleus, the large cells in the deep cerebellar nuclei and the vestibular nuclei and neurons of the lateral superior olivary nucleus. GluT mRNA does not appear to be present at high levels in all GAD-containing neurons, but is seen prominently in many neuronal populations that may use glutamate as a neurotransmitter, such as neocortical and hippocampal pyramidal cells, the granule cells of the cerebellum and neurons of the dentate gyrus of the hippocampus. The heaviest labelling of GluT mRNA is seen in the lateral reticular nucleus of the medulla. ISHH using probes directed against the mRNAs encoding these enzymes may be an important technique for identifying glutamate and aspartate using neuronal populations and for examining their regulation in a variety of experimental and pathological circumstances.

Animals↗
PubMed1994

Organization of vestibular nucleus projections to the caudal dorsal cap of kooy in rabbits.

This study used retrograde and anterograde tracing methods to characterize the origin and terminal distribution of vestibular nuclear projections to the caudal dorsal cap of the inferior olive in albino rabbits. Comparisons of the retrograde labeling patterns from Cholera toxin B fragment-horseradish peroxidase and Fluoro-Gold injection sites centred in either the caudal dorsal cap or the rostral dorsal cap plus ventrolateral outgrowth revealed that they receive projections from different vestibular nuclear regions. Tracer injections in the rostral dorsal cap and ventrolateral outgrowth produced a sparse bilateral distribution of labeled neurons in the superior vestibular nucleus and an almost exclusively ipsilateral pattern of labeled neurons in caudal pars alpha of the lateral vestibular nucleus. Injections in the caudal dorsal cap, though, labeled neurons bilaterally in the rostral medial vestibular nucleus, predominantly ipsilaterally in pars beta of the lateral vestibular nucleus and almost exclusively ipsilaterally in caudal pars alpha of the lateral vestibular nucleus and the rostral aspect of the inferior vestibular nucleus. Vestibular nucleus injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin indicated (1) that a predominantly ipsilateral projection to the caudal dorsal cap originates bilaterally from the pars beta of the lateral vestibular nucleus and the rostroventral aspect of the rostral medial vestibular nucleus, (2) that the medial half of the caudal medial vestibular nucleus is the source of a predominantly contralateral projection to dorsal cap, (3) that the caudal aspect of nucleus prepositus hypoglossi contributes a predominantly ipsilateral projection to the medial accessory olive and (4) that the rostral aspect of inferior vestibular nucleus and the dorsal and lateral aspects of the caudal medial vestibular nucleus project to nucleus beta of the medial accessory olive. In addition, axons containing anterogradely transported PHA-L were observed bilaterally in the oculomotor and abducens nuclei from injection sites involving pars beta of the lateral vestibular nucleus. It is hypothesized that bilateral vestibulo-caudal dorsal cap pathways coordinate activity in the left and right flocculus and nodulus during horizontal head movements to facilitate the performance of conjugate vestibulo-ocular and optokinetic reflexes.

Animals↗
PubMed1999

Modulation of vestibular function by nociceptin/orphanin FQ: an in vivo and in vitro study.

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. Nociceptin (100 nM-1 microM) potently inhibited the spontaneous discharge of the majority (86%) of MVN neurons tested in the rat dorsal brainstem slice preparation in vitro. This inhibition was dose-dependent and persisted after blockade of synaptic transmission in low Ca2+/Co2+ medium. The inhibitory effects were insensitive to the opioid antagonist naloxone, but were effectively antagonised by the selective ORL1 receptor antagonist, [Phe1Psi(CH2-NH)Gly2]Nociceptin(1-13)NH2. The majority of MVN neurons ( approximately 70%) were inhibited by both nociceptin and the delta-opioid receptor agonist, [D-ala2, D-leu5]-enkephalin (DADLE), while a minority of cells (approximately 30%) were selectively responsive either to DADLE or to nociceptin, but not both. Co-application of nociceptin and DADLE to neurons that were responsive to both agonists, resulted in an inhibitory response that was the same as or less than the inhibition evoked by either agonist alone. Intracellular whole-cell patch clamp recordings from identified Type A and Type B MVN cells showed that both these cell types are responsive to nociceptin, which induced membrane hyperpolarisation and decrease in input resistance consistent with its known effects on membrane K currents in other cell types. In alert rats, i.c.v. injection of nociceptin caused a significant decrease in the gain of the hVOR and resulted in a prolongation of post-rotatory nystagmus in darkness. The decrease in VOR gain and the increase in the VOR time-constant was significant even at low doses of nociceptin which did not cause other observable behavioural effects. These findings demonstrate that endogenously released nociceptin may have a hitherto unexplored role in the functional modulation of the neural pathways that mediate vestibular reflexes in vivo.

Action Potentials↗
PubMed1984

The efferent vestibular system in the cat: a horseradish peroxidase and fluorescent retrograde tracers study.

Neurons of the efferent vestibular system were investigated in the cat using retrograde axonal transport of horseradish peroxidase and fluorescent retrograde double labelling techniques. The number of efferent neurons was clearly higher than previously reported. A three dimensional reconstruction of the location of these neurons showed that they constitute a single group and did not give evidence of an eventual specialization based on neuron subpopulations. However, a study of cross-sectional areas of the horseradish peroxidase-labelled efferent neurons detected that the ipsilateral population contained a larger number of small neurons than the contralateral one. Double labelling by means of either 4',6-diamidino-2- phenylindol 2HCl in combination with horseradish peroxidase or Fast Blue in combination with Nuclear Yellow showed that 20% of efferent neurons project to both labyrinths. Such a high percentage raises the question of the role of these double-projecting cells and the specificity of their branching on vestibular receptors. This study expands previous work in the cat demonstrating that a much greater number of efferent neurons exists than had hitherto been assumed, among them 20% have both crossed and uncrossed projections.

Animals↗
PubMed1992

Simulating vestibular compensation using recurrent back-propagation.

Vestibular compensation is simulated as learning in a dynamic neural network model of the horizontal vestibulo-ocular reflex (VOR). The bilateral, three-layered VOR model consists of nonlinear units representing horizontal canal afferents, vestibular nuclei (VN) neurons and eye muscle motoneurons. Dynamic processing takes place via commissural connections that link the VN bilaterally. The intact network is trained, using recurrent back-propagation, to produce the VOR with velocity storage integration. Compensation is simulated by removing vestibular afferent input from one side and retraining the network. The time course of simulated compensation matches that observed experimentally. The behavior of model VN neurons in the compensated network also matches real data, but only if connections at the motoneurons, as well as at the VN, are allowed to be plastic. The dynamic properties of real VN neurons in compensated and normal animals are found to differ when tested with sinusoidal but not with step stimuli. The model reproduces these conflicting data, and suggests that the disagreement may be due to VN neuron nonlinearity.

Algorithms↗
PubMed1992

Effects of Ginkgo biloba extract (EGb 761) on the guinea pig vestibular system.

Previous studies have demonstrated that the administration of Ginkgo biloba extract (EGb 761) improves the compensation of the vestibular syndrome induced by transection of the VIIIth nerve. To investigate the mechanisms at play, the vestibular nuclei of alert guinea pigs were perfused with EGb 761. This perfusion always induced a stereotyped reversible postural syndrome that was the mirror image of the syndrome provoked by the unilateral lesion of the otolithical receptors. This result supports the hypothesis that EGb 761 has a direct excitatory effect on the lateral vestibular nuclei (LVN) neurons. In a second step, we quantified the horizontal vestibuloocular reflex (HVOR) of the normal guinea pig following IP injection of EGb 761. In normal guinea pig, IP administration of EGb 761 led to a reversible, dose-dependent decrease of the HVOR gain without affecting the phase of the reflex. These data help to explain the therapeutic effects of EGb 761 during vestibular syndromes and strongly suggest an impact at the neuronal level.

Animals↗
PubMed1979

Vestibular unitary responses to visual stimulation in the rabbit.

Vestibular nucleus (VN) neurons, identified by sinusoidal rotation about the vertical axis, were tested for their response to moving visual field, and to electric stimulation on the optic chiasm (OX) and super colliculus (SC). Incremental responses during the rotation were inhibited by visual stimulus in cerebellectomized animals. Single-pulse stimulation applied to the OX was ineffective in producing a positive response in these neurons as well or in any other unit. Thus, such a visual pathway to VN must be located inside the brainstem and contains multi-synapses. Effects of repetitive stimulations (60 Hz) to OX and SC were more predominant in the cerebellectomized animal than in the intact animal. Cerebellar inhibitory control on visual-vestibular kinkage was suggested.

Animals↗
PubMed2003

A subpopulation of dorsal raphe nucleus neurons retrogradely labeled with cholera toxin-B injected into the inner ear.

Previous studies have shown that: (1) raphe neurons respond to acoustic and vestibular stimuli, some with a latency of 10-15 ms; (2) alterations of the raphe nuclei alter the acoustic startle reflex; (3) the dorsal raphe nucleus (DRN) is the major source of serotonergic neurons; and (4) approximately 57% of the DRN neurons are nonserotonergic. In the present study, cholera toxin subunit-B (CTB) was injected into cat cochleas, and the brain tissue was examined after a survival period of 5-7 days. Aside from neurons which were known to project to the inner ear, i.e., olivocochlear and vestibular efferent neurons, a surprising new finding was made that somata of a subpopulation of DRN neurons were intensely labeled with CTB. These CTB-labeled neurons were densely distributed in a dorsomedian part of the DRN with some in a surrounding area outside the DRN. The present results suggest that a novel raphe-labyrinthine projection may exist. A future study of anterograde labeling with injections of a tracer in the DRN will be needed to establish the existence of a raphe-labyrinthine projection more thoroughly. A raphe-labyrinthine descending input, together with an ascending input from the inner ear to the DRN through intervening neurons, such as the juxta-acousticofloccular raphe neurons (JAFRNs) described by Ye and Kim, may mediate a brain stem reflex whereby a salient multisensory (including auditory and vestibular) stimulus may alter the sensitivity of the inner ear. As a mammal responds to a biologically important auditory-vestibular multisensory event, the raphe projections to the inner ear and other auditory and vestibular structures may enhance the mammal's ability to localize and recognize the sound and respond properly. The raphe-labyrinthine projection may also modulate the inner ear's sensitivity as a function of the sleep-wake arousal state of an organism on a slower time course.

Animals↗
PubMed1986

Brain stem and cerebellar deficits in eye movement control.

Recent experimental studies allow more precise functional-anatomical correlations in patients with ocular motor disorders. The abducens nucleus contains two groups of cells that together subserve ipsilateral horizontal conjugate gaze: Motoneurons with axons that innervate the lateral rectus and internuclear neurons with axons that cross the midline, ascend in the medial longitudinal fasciculus (MLF) and impinge upon medial rectus motoneurons. The pontine paramedian reticular formation (PPRF) contains burst neurons for horizontal saccades. The rostral interstitial nucleus of the MLF (riMLF) in the midbrain contains burst neurons for vertical saccades. The dorsal lateral pontine nuclei are important for relaying smooth pursuit commands from the cerebrum to the cerebellar flocculus. The medial vestibular nuclei contain neurons important for eccentric gaze-holding. The cerebellar flocculus is also important for gaze-holding as well as for smooth pursuit and the control of the amplitude and direction of vestibular responses. The cerebellar nodulus is important for controlling the duration of vestibular responses. The cerebellar dorsal vermis (and underlying deep nuclei) are important for controlling saccade accuracy.

Brain Stem↗
PubMed1993

Cellular distribution of parvalbumin immunoreactivity in the peripheral vestibular system of three rodents.

The cellular distribution of parvalbumin immunoreactivity in the vestibular peripheral system of mouse, rat, and guinea pig was investigated by light and electron microscopy. Parvalbumin was found in all neurons of the vestibular ganglia of these species but in the sensory epithelia immunoreactivity was restricted to type I hair cells localized exclusively in the central areas. The very intense staining pattern was similar in the cristae ampullares and utricles of all three species but a faint immunoreaction was also detectable in sensory cells of peripheral areas of rat cristae. The parvalbumin-immunoreactive type I sensory cells are connected by nerve fibres of the calyx unit type which are known selectively to contain calretinin.

Animals↗
PubMed1998

Schwann cells genetically modified to secrete human BDNF promote enhanced axonal regrowth across transected adult rat spinal cord.

The infusion of BDNF and NT-3 into Schwann cell (SC) grafts promotes regeneration of brainstem neurones into the grafts placed in adult rat spinal cord transected at T8 (Xu et al., 1995b). Here, we compared normal SCs with SCs genetically modified to secrete human BDNF, grafted as trails 5 mm long in the cord distal to a transection site and also deposited in the transection site, for their ability to stimulate supraspinal axonal regeneration beyond the injury. SCs were infected with the replication-deficient retroviral vector pL(hBDNF)RNL encoding the human preproBDNF cDNA. The amounts of BDNF secreted (as detected by ELISA) were 23 and 5 ng/24 h per 106 cells for infected and normal SCs, respectively. Biological activity of the secreted BDNF was confirmed by retinal ganglion cell bioassay. The adult rat spinal cord was transected at T8. The use of Hoechst prelabelled SCs demonstrated that trails were maintained for a month. In controls, no SCs were grafted. One month after grafting, axons were present in SC trails. More 5-HT-positive and some DbetaH-positive fibres were observed in the infected vs. normal SC trails. When Fast Blue was injected 5 mm below the transection site (at the end of the trail), as many as 135 retrogradely labelled neurones could be found in the brainstem, mostly in the reticular and raphe nuclei (normal SCs, up to 22, mostly in vestibular nuclei). Numerous neurones were labelled in the ventral hypothalamus (normal SCs, 0). Also, following Fast Blue injection, a mean of 138 labelled cells was present in dorsal root ganglia (normal SCs, 46) and spinal cord (39 vs. 32) rostral to the transection. No labelled spinal neurones rostral to the transection were seen when SCs were not transplanted. Thus, the transplantation of SCs secreting increased amounts of BDNF improved the regenerative response across a transection site in the thoracic cord. Moreover, the enhanced regeneration observed with infected SCs may be specific as the largest response was from neurones known to express trkB.

Adult↗
PubMed1975

Single-unit responses to natural vestibular stimuli and eye movements in deep cerebellar nuclei of the alert rhesus monkey.

To study the possible role of the cerebellum in the vestibular-ocular reflex, extracellular responses of cerebellar nuclear neurons were recorded in awake monkeys during natural vestibular stimulation; 115 neurons in the fastigial nucleus responded to horizontal sinusoidal accelerations applied to the head by means of whole-body rotation. More than 75% of these cells were located in a distinct layer, 500 mum thick, in the rostral part of the fastigial nucleus; they were excited by contralateral horizontal angular acceleration and inhibited by ipsilateral rotation (type IIf neurons). The remaining 25% of the population were scattered more caudally in the nucleus, and were excited by ipsilateral rotation and inhibited by contralateral rotation (type If). All showed fairly high resting discharges, averaging 50 spikes/s. Sinusoidal horizontal rotation (0.2--4.8 HZ) produced clear periodic modulation of the firing rate of fastigial neurons, which was approximately sinusoidal about the resting rate at low frequencies. As the frequency of oscillation (and the applied acceleration) increased, the sinusoidal modulation of unit firing increased in amplitude; at high stimulus frequencies the firing rate was usually driven to zero during the inhibitory part of stimulus cycle, but did not saturate in the excitatory half leading to an increase in the mean firing rate. The maximum firing rates of fastigial neurons were related to the peak acceleration by a power function. At all stimulus frequencies, the peak firing frequency of fastigial neurons lagged the input angular acceleration. Maximum firing of most units occurred just prior to the maximum velocity of the head. The gain and phase lag of the averaged unit discharge relative to head acceleration were calculated by Fourier analysis, using the fundamental as a first approximation of the response. Over a 20-fold stimulus range (0.2--4.0 HZ), mean phage lags of type IIf unit responses with respect to the applied acceleration remained relatively constant; the phase lag at 0.9 HZ measured 62 plus or minus 13 degrees. This phase lag is very similar to that recorded from vestibular nerve fibers (15), suggesting that type IIf fastigial neurons provide an excitatory signal to the ipsilateral vestibular nuclei which is in phase with direct vestibular afferent input, although functionally opposite in sign. Over the same frequency range, the gain decreased at minus- 18 dB/decade. Our data suggests that the majority of fastigial neurons work in parallel with flocculus Purkinje cells to functionally inhibit type Iv neurons in the ipsilateral vestibular nuclei.

Acceleration↗