Search NASA⌕ Search

SEARCH · Search NASA

Results for “Vestibular”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Subjective and nystagmus reactions considered in relation to models of vestibular function

Modelling will become increasingly important as more knowledge is accumulated, because it offers advantages in predicting reactions of individuals in a variety of situations, including novel aerospace environments, and in specifying a few parameters which should have considerable clinical significance. However, the need for continuing experimental crosschecks of these models has been illustrated by several sets of results which would not have been predicted by any existing models.

Guedry, F. E., Jr.↗
NASA NTRS1974

Models of the vestibular system and postural control

Applications of control theory and systems analysis to the problem of orientation and posture control are discussed, with the possible long range goals of contributing to the development of hardware for rehabilitation of the handicapped.

Young, L. R.↗
NASA NTRS1974

Studies on Auditory and Vestibular End Organs and Brain Stem Nuclei

Cats were exposed to tones of 125, 1000, 2000, and 4000 Hz at sound pressure levels in the range 120 to 157.5 db, and for durations of one hour (1000, 2000, 4000 Hz) or four hours (125 Hz). Pure tone audiograms were obtained for each animal before and after exposure. Cochleas of animals were examined by phase-contrast microscopy. Extent of inner ear damage and range of frequencies for which hearing loss occurred increased as exposure tone was decreased in frequency. For example, exposure to 4000 Hz produced damage in a restricted region of the cochlea and hearing loss for a relatively narrow range of frequencies; exposure to 125 Hz produced wide-spread inner ear damage and hearing loss throughout the frequency range 125 to 6000 Hz.

Ades, H. W.↗
NASA NTRS1975

Vestibular side effects in the orbital stage of Skylab II and III missions

None of the six astronauts were motion sick when tested (on or after Mission Day 8) in the workshop under experimental conditions which elicited motion sickness preflight and postflight. Skylab III but not Skylab II astronauts experienced motion sickness under operational conditions aloft. There were individual differences in the severity of the symptoms and susceptibility to motion sickness persisted for three to five days. The discussion centers around the reasons for the greater susceptibility to motion sickness under operational than experimental conditions aloft and the implication of Skylab findings for future manned space missions.

Graybiel, A.↗
NASA NTRS1980

Vestibular reactions in patients during occlusion form of chorioependymitis

A change in intracranial pressure during chorioependymitis is discussed. The inflammatory process in the choroid plexi and walls of the cerebral ventricles is described. The otoneurological method, not having any significant contraindications, can be employed repeatedly, quaranteeing control in dynamics over the course of the disease and effectiveness of treatment.

Ladyzhenskaya, E. A.↗
NASA NTRS1980

Responses of the frog primary vestibular afferents to direct vibration of the semicircular canal

Responses of primary afferents (PA) of lateral semicircular canal to sinusoidal vibration of the canal wall within the range 0.05-200 Hz (mean amplitudes 5-15 microns) in immobilized frogs were studied. Dynamic characteristics (gain, phase) of relative linear velocity of the vibrator (micron X/s) were examined. At 0.2 Hz, the gain was 5.35 + or - 3.19 imp X/s /micron X/s (mean; S.D.; n=14) and linearly decreased if the frequency rose. Phase lag of relative velocity at 0.05 Hz was 49.8 deg + or - 16.5 deg (n=13) and at 1 Hz 97 deg + or - 9.4 deg (n=22). At 100 Hz phase lag was about 240 deg. Three groups of PA are described: wide range PA reacting in the range from 0.05 up to 60-180 Hz; high frequency PA responding in the range from 20-40 up to 100-150 Hz; and low frequency PA responding in the range from 0.05 up to 2-20 Hz.

Orlov, I. V.↗
NASA NTRS1980

Dependence of vestibular reactions on frequency of action of sign-variable accelerations

It was revealed that during the tests with continuous action of sign variable Coriolis acceleration the development of kinetosis was proportionate to the time of head inclinations in the range of 1 to 4 seconds while illusions of rocking in sagittal plane was more expressed in fast inclinations. The obtained data provided the evidence of sufficient dependence of vestibulovegetative and vestibulosensory reactions on the period of repetition of sign variable Coriolis acceleration.

Lapayev, E. V.↗
NASA NTRS1981

The functional status of the human vestibular analysor following 56 days in an aqueous immersion medium

Two male volunteers were kept hypokinetic in the immersion and physiological parameters were evaluated following the experiment. Prophylactic measures (g-forces, physical exercises, and supplementary salt and water) were applied daily. Caloric and equilibrium tests were utilized to evaluate the physiological responses. The functional changes observed after the 56 day immersion were found to be of a moderate type which normalized quite quickly.

Matsnev, E. I.↗
NASA NTRS1980

Visual evaluation of nystagmus intensity in points to diagnose vestibular dysfunction

The amplitude of nystagmus multiplied by its frequency gives a value commensurate to the velocity of slow phase. If the amplitude and the frequency during the visual observation are expressed in relative units (e.g., in points ranging from 1 to 3) the results of multiplication are used for a relative evaluation of nystagmus intensity. The relative evaluation of nystagmus intensity is used to compare the responses and, in particular, to calculate the coefficients of labyrinth asymmetry and of directional preponderance. A suggestion is made to analyze the formal results of caloric tests using a simple graphic model reflecting the left-right interactions by which the obtained coefficients are conditioned.

Levashov, M. M.↗
NASA NTRS1981

Vestibular selection criteria development

The experimental elicitation of motion sickness using a short arm centrifuge or a rotating chair surrounded by a striped cylindrical enclosure failed to reveal any systematic group or consistent individual relationship between changes in heart rate, blood pressure, and body temperature and the appearance of symptoms of motion sickness. A study of the influence of vision on susceptability to motion sickness during sudden stop simulation shows that having the eyes open during any part of the sudden stop assessment is more stressful than having them closed throughout the test. Subjects were found to be highly susceptible to motion sickness when tested in free fall and in high force phases of flight. The effect of touch and pressure cues on body orientation during rotation and in parabolic flight are considered as sensory as well as motor adaptation.

Lackner, J. R.↗
NASA NTRS1981

Model simulation studies to clarify the effect on saccadic eye movements of initial condition velocities set by the Vestibular Ocular Reflex (VOR)

Voluntary active head rotations produced vestibulo-ocular reflex eye movements (VOR) with the subject viewing a fixation target. When this target jumped, the size of the refixation saccades were a function of the ongoing initial velocity of the eye. Saccades made against the VOR were larger in magnitude. Simulation of a reciprocally innervated model eye movement provided results comparable to the experimental data. Most of the experimental effect appeared to be due to linear summation for saccades of 5 and 10 degree magnitude. For small saccades of 2.5 degrees, peripheral nonlinear interaction of state variables in the neuromuscular plant also played a role as proven by comparable behavior in the simulated model with known controller signals.

Nam, M. H.↗