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PubMed1985

[Biophysical aspects on the result of the Spacelab experiment and consequences for Bárány's theory].

On testing the peripheral vestibular apparatus of astronauts with healthy labyrinths, nystagmus was observed when flushing the ears with hot or cold water even in the absence of gravitation. In the opinion of some scientists, this seems to refute Bárány's theory. They attempt to explain nystagmus as a result of compression. The hypothesis of Bárány, basing on terrestrial conditions, explains the peripheral impulse as the result of a convective flow caused by heating or cooling within the horizontal semicircular canal. However, if gravitation is absent any such circulation is excluded, because buoyancy is impossible without gravitation. The article shows, on the one hand, that the compression hypothesis cannot be correct, where as on the other Bárány's theory needs completion. For, in addition to the convective flow, the expansion of the endolymph resulting from heat must be considered. This effect occurs even in the absence of gravitation.

Aerospace Medicine↗
PubMed1993

Three-dimensional observation of the Golgi apparatus in the vestibular (Scarpa's) ganglion cell.

Ultrastructure of the Golgi apparatus and GERL was observed three-dimensionally from the functional view point of lysosome formation. GERL directly continues with rough endoplasmic reficulum. There are at least two systems for lysosome formation, i.e. dependent and not dependent systems on the Golgi stack respectively. GERL also continues with a trans Golgi saccule, indicating that GERL is a part of the Golgi apparatus.

Animals↗
PubMed2004

Histology of the utricle in kinetotically swimming fish: a parabolic aircraft flight study.

OBJECTIVES: Humans taking part in parabolic aircraft flights (PAFs) may suffer from space motion sickness, which is a form of kinetosis. As it has been repeatedly shown that some fish in a given batch also reveal kinetotic behaviour (especially so-called spinning movements and looping responses) during PAFs, and as a result of the homology of the vestibular apparatus of all vertebrates, fish can be used as model systems to investigate the origin of susceptibility to motion sickness. Therefore. we were prompted to examine the utricular maculae, which are responsible for the internalization of gravity in teleosteans of fish swimming kinetotically in microgravity (microg) in comparison with those of animals from the same batch who swam normally. MATERIAL AND METHODS: Larval cichlid fish (Oreochromis mossambicus) were subjected to PAFs. Post-flight, animals which had behaved normally or kinetotically during the microg phases were examined histologically The sizes of the inner ear utricular maculae as well as the numbers of sensory and supporting cells were determined. RESULTS: The total numbers of both sensory and supporting cells of the utricular maculae did not differ between kinetotic and normally swimming fish. Cell density (number of sensory and supporting cells/100 microm2) was, however, reduced in kinetotic animals (p < 0.0001), which seemed to be due to the presence of malformed epithelial cells of increased size in the kinetotic specimens. CONCLUSION: These results indicate that susceptibility to kinetosis may originate from genetically predisposed malformed sensory epithelia.

Acoustic Maculae↗
PubMed2001

[Perilymphatic fistula].

BACKGROUND: Perilymphatic fistula is leakage of perilymph from the inner ear to the middle ear. The perilymph surrounds the endolymphatic system in the inner ear (cochlea and the vestibular apparatus) and is most likely a cerebrospinal fluid filtrate. Leakage can occur through the fenestra vestibuli (the oval window), the fenestra cochleae (the round window), or pathological openings in the otic capsule. The cause of perilymphatic fistula can be trauma (barotrauma, head trauma, whiplash injury, iatrogenic trauma during ear surgery or ear syringing), chronic otitis media with cholesteatoma, congenital malformations or idiopathic. MATERIAL AND METHODS: We present 15 patients operated at Haukeland University Hospital from 1980 to 1997. RESULTS: Symptoms and signs are not very consistent, but dizziness and hearing loss are usual. The fistula test has low sensitivity and specificity, and otomicroscopy is not diagnostic. Imaging techniques with CT and MRI are seldom helpful unless in cases of inner ear abnormalities. Surgical exploration of the middle ear can be diagnostic, but even then it may in some cases be difficult to determine if a perilymphatic fistula is present. INTERPRETATION: The treatment of suspected perilymphatic fistula is primarily bed rest with elevated head, and avoidance of straining to facilitate spontaneous closure of a possible fistula. If the symptoms continue, or get worse, surgical exploration is indicated. The results are good regarding dizziness, but more uncertain as far as hearing improvement is concerned. Hearing improvement seems to be negatively correlated with the length of the delay before the fistula is closed.

Adult↗
PubMed1979

Voluntary nystagmus masquerading as Tullio's Phenomenon.

Nystagmoid eye movements elicited by humming loudly was initially misdiagnosed as Tullio's phenomenon (abnormal acoustical stimulation of the vestibular apparatus owing to labyrinthine fistula). Further workup lead to a final diagnosis of a form of voluntary nystagmus characterized in some reports as "hysterical mystagmus". Some of the characteristics of this example of voluntary nystagmus differed from generally accepted descriptions.

Adult↗
PubMed1995

Staggering gait in medical history.

Drunkenness and senility were recognized early as the basis of a staggering gait. To these were added venereal excesses, hence syphilis. Medical and scientific concerns began to be focused on "locomotor ataxia" in the 19th century with the systematic development of neuroanatomy and physiology. Rolando and Flourens were followed by Romberg and Todd, and later Friedreich, who all gave the spinal cord temporal precedence as a culprit over the cerebellum--and there were some forerunners. New spinal sensory pathways were delineated by Goll, Flechsig, and Gowers. In France, we must specially credit Duchenne as well as Bouillaud, and later Babinski, Marie, and Dejerine, for correcting, differentiating, extending, and underpinning current concepts. Failures of input and output, of conduction and central coordination were invoked and explained, among them the vestibular apparatus, as well as the causation by neoplasms, demyelination, degeneration, and infarction affecting even the frontal lobe, thalamus, and basal ganglia. Clinical testing was brought up to 20th-century standards essentially by Sherrington and Bárány, followed by Dandy, the neurosurgeon who showed how to replace ventricular fluid by air, more recently made obsolete by modern roentgenographic procedures. And tabes dorsalis, once the chief culprit, has practically become a medical anachronism thanks to penicillin.

Ataxia↗
PubMed1986

The pathogenesis of acute systemic candidiasis in a susceptible inbred mouse strain.

The histopathological features of the acute infection by Candida albicans in susceptible CBA/H mice, as well as its dissemination in various organs has been examined. The brain, in which the localization of blastospores is minimal, is the organ most severely affected. A significant deposition of blastospores occurs in lungs, liver, spleen and kidney, but of these organs, only in the kidneys is infection established. A transient myocarditis follows the minor blastospore deposition that occurs in the heart. Infection in the affected organs is characterized by abscess formation while in the brain the process is complicated by the development of hydrocephalus and a pachymeningitis that erodes the petrous temporal and involves the vestibular apparatus. There is also infection of the retinae with an accompanying endophthalmitis.

Acute Disease↗
PubMed1992

Vestibular control of swimming in lamprey. I. Responses of reticulospinal neurons to roll and pitch.

A method has been developed for recording the response of single neurons in the lamprey brainstem in vitro to natural stimulation of vestibular receptors. The brainstem dissected together with the intact vestibular apparatus could be rotated in space, in two perpendicular planes (transverse, the roll tilt, and sagittal, the pitch tilt), in one of them up to 360 degrees, and in the other one up to +/- 30 degrees. The responses of single reticulospinal (RS) neurons, in all four reticular nuclei of the brainstem, to roll and pitch were recorded extracellularly and, with small inclinations (up to +/- 45 degrees) also intracellularly. Two types of preparations were used, with and without the rostral part of the spinal cord. In the brainstem preparations, most RS neurons responded both to a definite brain orientation in space and to a change of the orientation (static and dynamic reactions). Responses to roll tilt were similar in all reticular nuclei: all cells were excited with roll tilt towards the contralateral side, this reaction was qualitatively preserved when the roll was performed in combination with different pitch inclinations. Responses to pitch tilt were less clearcut; some neurons were activated with nose-up deflection while others responded to nose-down tilt. In preparations including the spinal cord, responses of RS neurons to roll and pitch tilt differed from those in the isolated brainstem in that they were much less specific and stable. Roll and pitch tilts could trigger the spinal locomotor CPG, which, by sending "efference copy" signals back to the brainstem, produced modulation of RS neurons in relation to the locomotor rhythm.

Animals↗
PubMed1996

Directional organization of eye movement and visual signals in the floccular lobe of the monkey cerebellum.

The floccular lobe of the monkey is critical for the generation of visually-guided smooth eye movements. The present experiments reveal physiological correlates of the directional organization in the primate floccular lobe by examining the selectivity for direction of eye motion and visual stimulation in the firing of individual Purkinje cells (PCs) and mossy fibers. During tracking of sinusoidal target motion along different axes in the frontoparallel plane, PCs fell into two classes based on the axis that caused the largest modulation of simple-spike firing rate. For "horizontal" PCs, the response was maximal during horizontal eye movements, with increases in firing rate during pursuit toward the side of recording (ipsiversive). For "vertical" PCs, the response was maximal during eye movement along an axis just off pure vertical, with increases in firing rate during pursuit directed downward and slightly contraversive. During pursuit of target motion at constant velocity, PCs again fell into horizontal and vertical classes that matched the results from sinusoidal tracking. In addition, the directional tuning of the sustained "eye velocity" and transient "visual" components of the neural responses obtained during constant velocity tracking were very similar. PCs displayed very broad tuning approximating a cosine tuning curve; the mean half-maximum bandwidth of their tuning curves was 170-180 degrees. Other cerebellar elements, related purely to eye movement and presumed to be mossy fibers, exhibited tuning approximately 40 degrees narrower than PCs and had best directions that clustered around the four cardinal directions. Our data indicate that the motion signals encoded by PCs in the monkey floccular lobe are segregated into channels that are consistent with a coordinate system defined by the vestibular apparatus and eye muscles. The differences between the tuning properties exhibited by PCs compared with mossy fibers indicate that a spatial transformation occurs within the floccular lobe.

Animals↗
PubMed1985

Freeze-fracture studies on the perilymph-endolymph barrier in experimentally induced hydrops.

A double-blind study was performed on nine pigmented guinea pigs which were unilaterally operated on in order to create an endolymphatic hydrops. After 12-18 months, both inner ears of the animals were removed and investigated by the freeze-fracture technique. The ultrastructure of the epithelial cells lining the endolymphatic compartment of the cochlea and the vestibular apparatus was analyzed. Special attention was directed to possible changes of the tight junctions (zonulae occludentes) in these sites. The number and depth of strands between the cells of sensory and non-sensory epithelia of both operated and unoperated sides were compared by an examiner unaware of the operated side. After the code of double-blind study was broken, it was found that there were no significant differences between the operated and the unoperated ears. These results are discussed in relation to the late DC-potential decrease in experimentally induced hydrops.

Animals↗
PubMed1979

The synaptic ribbons of the guinea pig pineal gland in sterile, pregnant and fertile but non-pregnant females and in reproductively active males.

Pinealocyte ultrastructure has been studied in four sterile, four pregnant and three fertile but non-pregnant females, and also in three reproductively active male pigmented Duncan Hartley guinea pigs. Synaptic ribbons are dense, rod-like structures with a linear arrangement of clear vesicles periodically spaced on both sides of the rodlet. Although these structures were observed in the pinealocytes of all of the animals studied, they were scarce and difficult to locate in tissue from the fertile, non-pregnant females and from the reproductively active males. They were numerous in the pineal glands of the pregnant and sterile females. Typically they lie perpendicular to the cell membrane of the pinealocyte polar process and in close proximity to a polar process of a neighboring cell. The increased incidence of synaptic ribbons in pinealocytes which appear to be in a heightened state of activity strongly suggests a function for this structure. Synaptic ribbons are also present in sensory systems such as rods and cones of the retina, hair cells of the organ of Corti and hair cells of the vestibular apparatus. This fact, plus the photoreceptor function of pinealocytes in lower vertebrates, lends credence to the possibility that this structure may serve a sensory or receptor function in the guinea pig gland.

Animals↗
PubMed1987

Non-invasive estimation of afferent inputs for postural stability under low levels of alcohol.

The maintenance of human equilibrium is a complex process. Several physiological systems provide afferent information for postural stabilization. This study describes a noninvasive methodology to estimate the relative roles of interacting afferent inputs relevant for postural control. A multiaxis force platform in conjunction with specially designed test procedure provided semi-quantitative insight into the roles of vision, proprioceptors and vestibular apparatus in controlling postural sway when it was perturbed by a central nervous system perturbator such as alcohol. Experiments were conducted on 10 male and 10 female subjects. The males did not show statistically significant increases in body sway at these low levels of alcohol. For the females, the present methodology could detect subtle changes in postural sway at low blood alcohol levels ranging between 0.015% and 0.03%. At these low levels of alcohol, the results from females show that when the vision was excluded and the proprioception was modified, the postural sway was most affected. The postural instability experienced in this condition is probably due to inappropriate responses to proprioceptive inputs and lack of vision. Both male and female subjects showed a strong "eyes by standing surface" interaction. The proprioceptor manipulation alone did not affect the postural stability.

Adult↗
PubMed2001

Modeling postural control in the lamprey.

A phenomenological model of the mechanism of stabilization of the body orientation during locomotion (dorsal side up) in the lamprey is presented. The mathematical modeling is based on experimental results obtained during investigations of postural control in lampreys using a combined in vivo and robotics approach. The dynamics of the model agree qualitatively with the experimental data. It is shown by computer simulations that postural correction commands from reticulospinal neurons provide information sufficient to stabilize body orientation in the lamprey. The model is based on differences between the effects exerted by the vestibular apparatus on the left and the right side.

Animals↗
PubMed1975

Ocular torsion and the function of the vertical extraocular muscles.

The vertical corneal meridia are not kept perpendicular to the horizon in human and nonhuman primates when the head or body is tilted, i.e., compensatory counter-rolling of the eyes does not occur. The slight torsional displacement of the vertical corneal meridia noted by many observers may be the result of rotation around an axis or to translation of the globe. The neurologic and structural systems that control the actions of the vertical muscles in human and nonhuman primates do not appear to provide a mechanism for wheel-rotation of the eyes around the pupillary axis. Ocular torsion is not a normal function of the vertical extraocular muscles. Their function is probably the reverse, i.e., the inhibition or prevention of ocular torsion and the stabilization of the eyes when the head or body inclines. Torsional displacement of a vertical corneal meridian occurs only when there is an abnormal muscle imbalance. Wheel-like movements (cycloduction) around the pupillary axis or visual line do not occur. Torsional displacement of a vertical corneal meridian occurs only with a simultaneous vertical movement. The vertical rectus and the oblique muscles in man work together to produce vertical ocular movements regardless of head position of body posture while maintaining the vertical corneal meridia parallel to the sagittal plane of the head. The vestibular apparatus may be responsible for distributing innervation among these muscles, enabling them to function in this manner.

Animals↗