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At least 1,171 records · Page 65Linked to original sources
PubMed1996

The effect of gentamicin on cytoskeletons in the vestibular sensory cells: a high-resolution scanning electron microscopic investigation.

The effect of gentamicin on the cytoskeletal organization of guniea pig vestibular sensory cells was investigated employing the saponin perfusion method and scanning electron microscopy. The intermediate filaments and microtubules were noted to have degenerated following gentamicin intoxication. Such degeneration was not linked with primary mitochondrial damage, but closely related to subsequent degeneration of Golgi apparatus and of endoplasmic reticulum. These findings suggest that microtubules and intermediate filaments work closely together to maintain the structural integrity of both the Golgi apparatus and the membrane-bound organelles, which can be altered by ototoxic drugs before the degeneration of membrane-bound organelles.

Animals↗
PubMedDate not supplied

Use of infrared TV cameras built into head-mounted display to measure torsional eye movements.

PURPOSE: The head-mounted display (HMD) has produced conflict between visual and vestibular stimuli because the HMD image does not move with the head motion of the wearer. The HMD can show binocular parallax three-dimensional (3D) images, in which vergence and accommodation conflict. Thus, the HMD may affect the normal visual/vestibular functions. We attempted to develop a system that makes possible the measurement of torsional eye movements, vergence eye movements, and pupillary responses of the HMD wearer. METHODS: Our apparatus is composed of two infrared CCD cameras installed in the HMD. Iris images produced by these cameras are analyzed by a personal computer using free software. Further, a third camera fixed on the HMD projects an image of the view as the subject sees it, via video tape recorder or frame memory to the HMD. Images can be stored, replayed, or frozen. RESULTS: Our system can measure torsional eye movement with 0.20 degrees resolution every 1/30 (or 1/60) seconds even though the pupil size alternates during measurement. Binocular eye movement and pupillary response are also measured. CONCLUSION: A system was developed which can be used for assessment of the effect of 3D HMD on the visual system. A third camera coupled with HMD can control visual stimulus independently of head motion (vestibular stimulus).

Eye Movements↗
PubMed2004

Motion sickness induced by optokinetic drums.

Motion sickness is not only elicited by certain kinds of self-motion, but also by motion of a visual scene. In case of the latter, optokinetic drums are often used and a visual-vestibular conflict is assumed to cause the sickness. When the rotation axis is Earth vertical however, different studies show different results. Here, we propose that visual-vestibular conflicts per se do not cause sickness whereas subjective vertical mismatch theory can reconcile the disparate findings. The theory attributes the nausea induced by horizontal optokinetic stimulation to the subjects self-inducing pseudo-Coriolis by head movement. This highlights the shortcomings of an optokinetic apparatus--that is non-rigid or inaccurately oriented--and the importance of constraining the subject's behavior.

Coriolis Force↗
PubMed2000

Canalicular reticulum in vestibular hair cells.

A membrane limited system referred to as canalicular reticulum (CR) has been demonstrated in the apical cytosol of the cochlea's inner and outer hair cells. Similarities between cochlear and vestibular hair cells prompted investigation of the presence of CR in hair cells of the gerbil vestibular labyrinth. A method of fixation with glutaraldehyde followed by an osmium-ferrocyanide mixture demonstrated abundant CR in the apex of both type I and type II hair cells. The CR was closely associated with numerous Golgi zones in the apex of the vestibular hair cells, indicating its genesis from Golgi cisternae. Also preserved in upper cytosol were discrete complexes of mitochondria with granular reticulum. These complexes offered a possible site for generating the membrane in Golgi zones and CR. Single and parallel cisternae of granular reticulum were observed in the basal half of the hair cells together with numerous synaptic-like vesicles. These cisternae with their terminal blebbing and accompanying canaliculi were interpreted as novel structures mediating synaptic vesicle genesis in vestibular hair cells in a manner comparable to that postulated for cochlear inner hair cells.

Animals↗
PubMed1995

Melanocytes in the dark cell area of human vestibular organs.

By using surgical materials obtained from 7 cases of vestibular schwannoma, the ultrastructure of melanocytes in the dark cell area of human vestibular organs was examined by light microscopy and electron microscopy. Paraffin sections were stained with hematoxylin and eosin. Glutaraldehyde-fixed specimens were observed by electron microscopy. Melanocytes were found in the subepithelial layer of the dark cell area. Melanocytes had round or spindle-shaped nuclei and clear cytoplasm with brown pigment granules which were thought to be melanin granules. Besides melanocytes, there were fibroblasts and small blood vessels. By electron microscopy we found melanocytes with round shaped melanosomes in various stages of pigmentation, well-developed Golgi apparatus and endoplasmic reticulum in the cytoplasm, and many cytoplasmic processes. There were pinocytotic vesicles just under the limiting membrane of the melanocytes, and intermediate filaments were abundant in the cytoplasm. On the other hand long-spacing collagen was found in the connective tissue area around melanocytes.

Adult↗
PubMed1990

Contribution to knowledge of the morphogenesis of the nasal apparatus of the domestic sheep (Ovis aries L.).

The author studied the morphogenesis of the nasal apparatus in a sheep (Ovis aries L.) embryo with a length of 57 mm, at the optimum stage of development of the chondrocranium, as a part of his studies of development of the nasal apparatus in ungulates. The nasal apparatus is in general constructed according to the general scheme for mammals. Attention is drawn to the development of the superior alar cartilage, which is reminiscent of the situation in reptiles, to the strikingly developed atriturbinale auctorum (the author does not agree with this morphological designation, which is reserved for the vestibular turbinale in birds), to the well developed anterior paraseptal complex, to the extremely large maxilloturbinale and to the massive trunk of the ethmoturbinale I, which suppresses the corresponding recesses. The olfactory labyrinth is developed at three levels, the upper (rostral) level corresponding to the frontoturbinalia region, the middle to the ethmoturbinale I and the third (caudal) level to the region of the ethmoturbinalia II, III and IV (the recessus ethmoturbinalis). There is no foramen epiphaniale, no crista semicircularis and no crista Galli. A posterior paraseptal cartilage is present; in the author's opinion it is joined to the lamina orbitonasalis and not to the lamina transversalis post., since the latter is absent.

Animals↗
PubMed2000

Vestibular and visual contribution to fish behavior under microgravity.

Vestibular and visual information are two major factors fish use for controlling their posture under 1 G conditions. Parabolic flight experiments were carried out to observe the fish behavior under microgravity for several different strains of Medaka fish (Oryzias latipes). There existed a clear strain-difference in the behavioral response of the fish under microgravity: Some strains looped, while other strains did not loop at all. However, even the latter strains looped under microgravity conditions when kept in complete darkness, suggesting the contribution of visual information to the posture control under microgravity. In the laboratory, eyesight (visual acuity) was checked for each strain, using a rotating striped-drum apparatus. The results also showed a strain-difference, which gave a clue to the different degree of adaptability to microgravity among different strains. Beside loopings, some fish exhibited rolling movement around their body axis. Tracing each fish during and between parabolas, it was shown that to which side each fish rolls was determined specifically to each individual fish, and not to each strain. Thus, rolling direction is not genetically determined. This may support the otolith asymmetry hypothesis. Fish of a mutant strain (ha strain, having homozygous recessive of one gene ha) have some malfunction in otolith-vestibular system, and their behavior showed they are not dependent on gravity. Morphological abnormalities of their ear vesicles during the embryonic and baby stages were noted. Their eyesight and dorsal light responses were also studied. Progress in the project of establishing a new strain which has good eyesight and, at the same time, being deficient in otolith-vestibular system was reported. Crosses between the strain of good eyesight and ha strain were made, and to some extent, F2 fish have already shown such characteristics suited for living under microgravity conditions.

Animals↗
PubMed1978

Influence of pyramidotomy on limb flexion movements induced by cortical stimulation and on associated postural adjustment in the cat.

Flexion movements induced by cortical stimulation and the associated postural adjustments in bilaterally pyramidotomised cats have been studied by means of an apparatus which measures separately the changes of force under each limb in the upright position of the animal. The results show: (1) The general motor behaviour of the animal is not affected by the lesion. The principal deficit is loss of tactile placing reaction in the forelimbs; there also appears a state akin to a vestibular syndrome when a light restraining harness is placed around the back and chest. (2) Stimulation of the motor cortex continues to evoke flexion movements of the contralateral limbs together with associated postural adjustment. Coordination between movement and postural adjustment is generally similar to that observed before pyramidal section, and response thresholds are unchanged. (3) Measurements reveal great quantitative modification both of the movement and the postural adjustment after the lesion. Weight shift latencies are increased and more dispersed in time, while the weight shifts themselves are reduced in amplitude and speed. (4) All these changes are more marked in the case of forelimb, rather than hindlimb, flexion, emphasising the greater degree of pyramidal influence on forelimb activity in the normal animal. (5) The results as a whole underline the ability of non-pyramidal systems, under the control of the motor cortex, to bring about both limb flexion and the associated postural adjustments in the absence of the corticospinal pathway.

Animals↗
PubMed1977

Somatosensory motion after-effect following earth-horizontal rotation about the Z-axis: a new illusion.

During rotation about the Z-axos while recumbent one is exposed to a changing pattern of pressure cues over the body surface. If the body is only loosely padded in the experimental apparatus, then apparent motion of part of the body surface may be experienced sometime after rotation has been terminated. This somatosensory motion aftereffect of opposite sign is temporarily abolished if one looks at the affected body area, but is again re-experienced when the gaze is shifted elswhere. The similarity of this motion aftereffect to those contingent on vestibular and visual stimulation is discussed.

Humans↗
PubMed2001

Immunohistochemical localization of Ca(2+)/calmodulin-dependent protein kinase kinase beta in the rat central nervous system.

We examined regional and intracellular distribution of Ca(2+)/calmodulin-dependent protein kinase kinase beta (CaM-KK beta), which activated Ca(2+)/calmodulin-dependent protein kinase I and IV (CaM-K I and IV) immunohistochemically in the central nervous system of the rat by light and electron microscopy. Although most neurons in the brain and spinal cord exhibited the immunoreactivity, no labeled neurons were observed in the globus pallidus or entopeduncular nucleus, and only a small number of neurons showed weak immunoreactivity in the substantia nigra pars reticulata. In general, the immunoreactivity was observed both in the cytoplasm and cellular nucleus, although the immunoreactivity was not found in the cellular nucleus in some large neurons such as in the mesencephalic trigeminal nucleus, lateral vestibular nucleus or gigant cellular reticular formation. As to motoneurons of the cranial nerve nuclei and the anterior horn of the spinal cord, they revealed the immunoreactivity both in the cytoplasm and nucleus. The reaction product appeared as fine granules in the cytoplasm and nucleus under light microscopy. Electron microscopic observations confirmed that the reaction product was localized mainly on the Golgi apparatus or on the nuclear chromatin. Immunolabeling for antibody against CaM-KK beta was discussed with the distribution of CaM-K I, IV and another CaM-KK, CaM-KK alpha, in the central nervous system.

Animals↗
PubMed1992

[The Romberg head-shake test within the scope of equilibrium diagnosis].

We review the standard functional tests of static and dynamic equilibrium and discuss the value of these tests. The pendular platform test and the tilting table test were developed for provocation of the balance system, but are not used in clinical investigation because of the complicated apparatus and the difficulties of judgement of the curves recorded. A simple modification for provocation of the balance system, available in the clinic, the consulting room or the doctor's office is recommended, consisting of horizontal head-shaking in the Romberg position during posturographic recording. In healthy subjects little increase of body sway is found, but in patients with peripheral or central vestibular disorders a distinct tendency of disequilibrium is seen.

Adult↗
PubMed1999

[The normal parameters in people with static posturography].

OBJECTIVE: To get the normal parameters of static posturography in people. METHOD: 279 normal people from 5 to 80 year old were measured when their eyes opened and closed separately by G-5500 gravity sway apparatus. RESULT: The normal parameters of static posturography were acquired. CONCLUSION: The result can be taken as normal in clinical examination.

Adolescent↗
PubMed1984

Vestibular stimulation and eye contact in autistic children.

Five autistic boys ages 5-1 to 5-10 were studied to determine whether stimulation of the macular receptors of the inner ear through linear motion influences the boys' eye contact with the investigators. The duration of eye contact was measured during linear motion on a motor-driven oscillator and on two hand-operated swings and compared to the duration of eye contact when the macular receptors were not stimulated. Because the boys varied in cooperation, the tests could not be performed using the same apparatus with each child; therefore results were analyzed separately for each child. Four of the five boys showed longer eye contact while on the motor driven oscillator (p less than .0005), and two of these also showed longer contact when on a manually operated swing (p less than .025). The fifth child resisted the use of the oscillator and did not show longer eye contact while on it (p greater than .05), but did so when on two different swings (p less than .005).

Autistic Disorder↗