Basic and Applied Aspects of Vestibular Function
Publication Year: 1988
Published by: Hong Kong University Press, HKU
Table of Contents
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It is a singular honour to have been invited to write a foreword to the proceedings of this fine symposium on Basic and Applied Aspects of Vestibular Function. In view of my personal commitment to the field it was particularly unfortunate that personal constraints prevented my joining the close knit family of friends and colleagues gathered...
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This volume is the outcome of the International Symposium on Basic and Applied Aspects of Vestibular Function held in Hong Kong, September 13-16, 1987, in conjunction with the Centenary Celebration of the Faculty of Medicine, University of Hong Kong. The Symposium, officially sponsored by the National Aeronautics and Space Administration, U.S.A. and the University of Hong Kong, provides a forum for...
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Symposium Participants and Group Photograph
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1. The functional organization of the vestibular labyrinth and of some of its central pathways
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The relation between the peripheral morphology and the physiology of vestibular-nerve afferents was studied in the semicircular canals of the chinchilla. Some fibers end as calyces supplying type I hair cells. Other fibers give rise to boutons contacting type II hair cells. Still other fibers, so-called dimorphic afferents, innervate both type I and type II hair cells. Dimorphic...
2. Morphological and functional characteristics of semicircular canal afferents sensitive to head tilt
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The responses of gerbil lateral semicircular canal afferents (LCAs) to low frequency head tilts about the interaural axis were tested by oscillating the animals sinusoidally �10� at 0.01 and 0.05 Hz. Angular acceleration was less than 1.0 �/sec2. Average response gains and phases, re: nose down pitch, were calculated for neurons that exhibited a systematic modulation of activity...
3. Spectral analysis of the spontaneous activity of tilt-sensitive units in the vestibular system of the decerebrate cat
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Spontaneous activity of 69 tilt-sensitive units in the brainstem of decerebrate cat was analysed using a Fast Fourier Transform. Spikes were treated as binary events. Frequency spectra of 47 units were studied with the head fixed in one position. The spectra of the remaining 22 units were compared at 2 different head positions. Averaged spectral profiles could be grouped...
4. Functional organization of the horizontal vestibulo-oculomotor system in the cat brain stem
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Spikes of single neurons were recorded in the cat prepositus hypoglossi nucleus and the underlying reticular formation and were identified as type n neurons by horizontal rotation. Among these neurons, those activated by contralateral vestibular nerve stimulation with short latencies were selected for study. Approximately one third of the thus identified neurons exhibited...
5. Physiological and morphological properties of brain stem neurons related to vestibular and saccadic eye movements in the cat
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Single unit recordings were made from burster-driving neurons (BDNs) in the dorsomedial brain stem caudal to the abducens nucleus in the cat. BDNs were identified by their activation from the contralateral vestibular nerve, type II response to horizontal rotation, and characteristic firing pattern during nystagmus. When nystagmus was absent, firing responses...
6. Multidimensional analysis of vestibuloocular and vestibulocollic reflexes
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The neural transformations that underlie the vestibuloocular and vestibulocollic reflexes (VOR and VCR) depend upon the geometry of the semicircular canals and extraocular or neck muscles. In the cat, where these have been measured, an analysis of spatial transformations of the VOR and VCR suggests that quite...
7. Responses of vestibular nuclear neurons to bidirectional off-vertical axis rotations in normal and hemilabyrinthectomized cats
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The responses of tilt-sensitive vestibular nuclear units to slow constant velocity off-vertical axis rotations (OVAR) in 360� clockwise (CW) and counterclockwise (CCW) directions were studied in labyrinth-intact and acute unilaterally labyrinth-ectomized cats, with an aim to understand the contribution of otolith...
8. Vestibular control of the cat forelimb
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In response to tilt, the vestibular system produces reflex responses in the forelimb extensor muscles of the decerebrate cat. We have examined the spatial and temporal properties of the reflex, as well as the responses of central vestibular neurons and spinal intemeurons. The major spatial characteristic of the reflex is that roll (lateral) tilt produces much larger responses than...
9. Properties of vestibulospinal neurons receiving inhibitory inputs from the lingula of the cerebellum
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Although being referred to as the tail area, the lingula (lobule I of Larsell), together with lobule IIa, received convergent inputs from the labyrinth and neck afferents, but not from the tail. Electrical stimulation of lobules I-lla inhibited activities of a certain population of vestibulospinal neurons in the lateral vestibular nucleus. The majority of these neurons sent their axons...
Adaptation and Motion Sickness
10. Neurochemical and neuropharmacological studies on vestibular compensation/adaptation
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In squirrel monkeys after unilateral vestibular lesion, the dynamic change of GABA-like immunoreactivity in the bilateral vestibular nuclei showed a good correlation with that of functional motor balance compensation. Such neurochemical changes were also found after repeated unilateral vestibular...
11. Quantitative assessment of sensorimotor performance affected by motion sickness inducing stimulation
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Sensorimotor performance of consicous cats was studied by analysing the head orienting response (HOR) to a 70 dB SPL sound presented suddenly in an azimuthal plane. The same animals were then subjected to sinusoidal vertical accelerations for 30 minutes. The onset latency, end latency and the end direction of HOR were analysed within one minute after exposure...
12. Serotonergic mechanisms in emesis
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The observation that the CSF of cats which are susceptible 10 motion sickness contained lower baseline levels of 5-hydroxyindoleacetic acid, among other constituents, led to the hypothesis that serotonin inhibits emesis. The hypothesis was tested by administration of the serotonin-IA agonists buspirone and 8-OHDPAT before motion testing in cats susceptible to motion...
13. Immunocytochemical localization of glutamic acid decarboxylase (GAD) and substance P in neural areas mediating motion-induced emesis. Effects of vagal stimulation on GAD immunoreactivity
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Immunocytochemical methods were employed to localize the neurotransmitter amino acid 'Y-aminobutyric acid (GABA) by means of its biosynthetic enzyme glutamic acid decarboxylase (GAD) and the neuropeptide substance P in the area postrema (AP), area subpostrema (ASP), nucleus of the tractus solitarius...
14. Recovery from unilateral labyrinthectomy in primate: Effects of visual inputs and considerations upon Ewalds second law
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We investigated recovery from unilateral labyrinthectomy in monkeys. We found that visual experience after labyrinthectomy was necessary for animals to recover correct amplitude and to restore symmetry of VOR gain, but visual experience was not necessary for resolution of spontaneous nystagmus. Our results also revealed the nonlinearity in VOR gain known...
15. Experimental studies of gastric dysfunction in motion sickness: The effect of gastric and vestibular stimulation on the vagal and splanchnic gastric efferents
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The experiments were conducted in anaesthetized rats. In the first part of the experiments, the effect of CuSO4 on the afferent activity in the gastric branch of the vagus nerve was investigated. Gastric perfusion of CuSO4 solution (0.04% and. 0.08%) provoked an increase in afferent activity. In the second part of the experiments, the reflex effects of gastric perfusion of...
16. The effects of area postrema lesions and selective vagotomy on motion-induced conditioned taste aversion
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Conditioned taste aversion (CTA) is one of several behaviors which has been suggested as a putative measure of motion sickness in rats. A review is made of studies which have used surgical disruption of area postrema or the vagus nerve to investigate whether CTA and vomiting induced by motion may depend on common neural pathways or structures. When the chemoreceptive...
17. Observations of vestibular functions in four patients with inner ear anomaly
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All of four patients, aged 4, 7, 8, and 12, had different degrees and kinds of deafness. CT scan of the temporal bones revealed no semicircular canals and enlarged vestibules on both sides in the first three patients; no lateral canals in the last. The development of the patients' motor function was more or less retarded in the early stage of childhood; the retardation was remarkable...
18. The otolith-ocular reflex in man
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Horizontal and vertical eye movements were induced in normal human subjects by sinusoidal linear acceleration on a parallel swing. The swing frequency was 0.3 Hz and the peak horizontal and vertical acceleration ranged from 0.17 to 0.48 and 0.03 to 0.34 g respectively. Eye movements were recorded with the scleral search coil technique. With the subjects seated in the dark, swing displacement...
Ventures in Space
19. Vestibular factors influencing the biomedical support of humans in space
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This paper will describe the biomedical support aspects of humans in space with respect to the vestibular system. The vestibular system is thought to be the primary sensory system involved in the short-term effects of space motion sickness, although there is increasing evidence that many factors play a role in this complex set of symptoms. There is the possibility that an...
20. MIT/Canadian Spacelab experiments on vestibular adaptation and space motion sickness
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Experiments on sensory-motor adaptation to weightlessness and re-adaptation to 1 g were conducted on Space Shuttle/Spacelab Missions 1 and D-1 by a team of investigators from MIT and Canada. Results from both missions are reviewed in the context of a sensory re-interpretation hypothesis and the...
21. Somatosensory-vestibular-sympathetic interactions in man under weightlessness simulated by head-out water immersion
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The purpose of this study was to clarify how the somatosensory-vestibular-sympathetic interactions, particularly the vestibulo-sympathetic reflex responses, are modified in man under weightlessness. The responses of muscle sympathetic nerve activity (MSA) to caloric vestibular stimulation were analyzed in standing human subjects during head-out water immersion, concomitantly...
22. Microgravity vestibular investigations: Experiments on vestibular and sensory-motor adaptation to space flight
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A set of nine experiments, known collectively as the Microgravity Vestibular Investigations (MVI), have been conditionally manifested on the First International Microgravity Laboratory (lML-1) Spacelab Mission scheduled for flight in 1991. These experiments are supported by a team of 17 investigators from the United States, France, United Kingdom, and Canada. The...
23. Macular bioaccelerometers on earth and in space
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Spaceflight offers the unique opportunity to study linear bioaccelerometers (vestibular maculas) in the virtual absence of a primary stimulus, gravitational acceleration. Macular research in space is particularly important to NASA because the bioaccelerometers are proving to be weighted neural networks in which information is distributed for parallel processing. Neural networks are plastic and highly adaptive to new environments. Combined morphological...
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Page Count: 246
Publication Year: 1988