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Results for “Vestibular Neuronitis”

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PubMed1990

[The responses of frog vestibular neurons to the combined temperature microstimulation of the semicircular canals].

Controlled temperature microstimulation of the frog semicircular canal (heating of 2 sec duration, peak amplitude from 0.5 to 5.0 degrees C above the temperature level of the labyrinth, 17-19 degrees C) may be considered as an analogue of angular acceleration in the plane of the canal. Combined temperature microstimulation of some canals may be considered as a physical model of complicated space rotations. Responses of the frog vestibular nuclei's neurons (n = 278) to temperature microstimulation showed that 80% of them had inputs from 1-2 canals and only 20% of neurons--from 3-6 canals. 201 neurons (72.3%) had ipsilateral inputs only; 14 neurons (5%)--contralateral ones only; 63 neurons (22.7%) had both inputs. The most effective excitatory inputs were ipsilateral horizontal, ipsilateral posterior and contralateral posterior canals; the least effective were contralateral horizontal and contralateral anterior canals. Latent canal inputs (excitatory as well as inhibitory) seem to exist as revealed in combination with the effective inputs.

Animals↗
PubMed1977

Synaptic actions of individual vestibular neurones on cat neck motoneurones.

1. Unitary synaptic potentials evoked by the activity of single vestibulocollic neurones were recorded by means of spike-triggered signal averaging in neck extensor motoneurones of decerebrate cats. Properties of the vestibulocollic neurones which produced the potentials were examined.2. Vestibulocollic neurones were first identified as projecting to the C3 grey matter by antidromic microstimulation within the C3 extensor motoneurone pool. The spontaneous or glutamate-driven activity of the vestibulocollic neurones was then used to trigger the averaging computer. In this way ten inhibitory and two excitatory neurones were identified (20% of neurones tested).3. Action potentials in local branches of vestibulocollic neurones were usually recorded in the vicinity of motoneurones. Mean orthodromic conduction time from the foot of the extracellular spike, recorded in the vestibular nuclei, that triggered the averager was 0.72 msec. Mean synaptic delay was 0.4 msec.4. I.p.s.p.s had a mean time to peak of 0.81 msec and were readily reversed by injection of hyperpolarizing current. These data, together with the shape indices of i.p.s.p.s indicate that they are generated proximally on motoneurones.5. All vestibulocollic neurones making synapses with motoneurones were monosynaptically driven by stimulation of the ipsilateral vestibular nerve. Four out of seven tested were inhibited by stimulation of the contralateral vestibular nerve (commissural inhibition).6. Two excitatory neurones were located in Deiters' nucleus or on the Deiters'-descending border. Inhibitory neurones were found relatively medially in the vestibular complex in the medial, descending and Deiters' nuclei.7. Vestibulocollic neurones acting on motoneurones were tested for axon branching to more caudal levels of the spinal cord with electrodes placed at C5-7. Both of the excitatory and two out of nine inhibitory neurones branched.

Action Potentials↗
PubMed1997

[Limbic mechanisms regulating vestibular neuron reactions in vibration].

Acute experiment on rabbits (extracellular registration) studied influence of limbic cortex on neuron activity of Deuters nucleus before and after exposure to low-frequency vibration (5 Hz, 30 minutes). The authors discuss mechanisms underlying changes in activity and response of vestibular neutrons to electric simulation (5 and 60 Hz) of limbic cortex before and after vibration.

Animals↗
PubMed1999

Identification of head motions by central vestibular neurons receiving linear and angular input.

Most naturally occurring displacements of the head in space, due to either an external perturbation of the body or a self-generated, volitional head movement, apply both linear and angular forces to the head. The vestibular system detects linear and angular accelerations of the head separately, but the succeeding control of gaze and posture often relies upon the combined processing of linear and angular motion information. Thus, the output of a secondary neuron may reflect the linear, the angular, or both components of the head motion. Although the vestibular system is typically studied in terms of separate responses to linear and angular acceleration of the head, many secondary and higher-order neurons in the vestibular system do, in fact, receive information from both sets of motion sensors. The present paper develops methods to analyze responses of neurons that receive both types of information, and focuses on responses to sinusoidal motions composed of a linear and an angular component. We show that each neuron has a preferred motion, but a single neuron cannot code for a single motion. However, a pair of neurons can code for a motion by the relative phases of firing-rate modulation. In this way, information about motion is enhanced by neurons combining information about linear and angular motion.

Animals↗
PubMedDate not supplied

The pathology of facial and vestibular neuronitis.

OBJECTIVE: To measure disease of idiopathic nature in the ganglia of the human facial (FN) and vestibular nerves (VN). METHOD: One hundred horizontally sectioned human temporal bones (TB) were examined under light microscopy. The TB were sectioned at 20 microm, and every 10th section was stained with hematoxylin and eosin and mounted. The volume fractions (VF) of degenerated cells in the FN ganglion and focal axonal degeneration in the VN were measured with stereologic techniques. RESULTS: Twenty-five TB were excluded because of artifact or poor staining of the FN and VN. Fifty-one TB contained degenerated cells in the FN meatal ganglion (MG) and/or focal axonal degeneration in the VN. Thirty-one FN had degenerated cells in the MG (VF = 1% to 55%) and none in the geniculate ganglion. In 45 TB, focal axonal degeneration was found in the VN (VF = 1% to 50%; the VF was less than 15% in all but one TB). MG and VN degeneration occurred together in 25 TB. None of the cases had a history of FN paralysis, but 20 had a history of vertigo. Twenty-four TB from patients of similar ages with similar otopathologies did not reveal degeneration in the FN or VN. CONCLUSION: The FN and VN lesions in these 51 TB may be virus-induced and reflect a higher incidence of idiopathic FN and VN neuronitis than previously thought.

Adolescent↗