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Biomedical subjects

F E Guedry

Publications and source records attributed to F E Guedry.

At least 37 records · Page 2Linked to original sources
PubMed1978

Motion sickness susceptibility: a retrospective comparison of laboratory tests.

A test battery designed primarily to assess vestibular function has been used for several years to evaluate individuals referred to our laboratory. Because some of the test conditions have proved to be nauseogenic to some individuals, methods of assessing disturbance during these procedures have been used to pursue a second goal, viz., the estimation of motion sickness susceptibility. This report, which focuses on the latter goal, is a retrospective comparison of results on three tests obtained from two groups of subjects, one of which was a group of Navy and Marine aviation personnel who had suffered multiple attacks of airsickness. Results from three laboratory tests of motion sickness susceptibility indicated that there are substantial differences between the airsick group and the unselected comparison group on observer ratings and individual self-ratings of motion sickness symptoms. The provocative stimuli in each laboratory test, as well as suggestions concerning how multiple tests may prove effective in predicting motion sickness, are discussed.

Aerospace Medicine↗
PubMed1977

Antisomatogyral illusion.

Following voluntary ambulatory turning (eight turns), perceived motion is reversed in direction relative to a) aftereffects of passive rotation and b) predictions from current concepts of immer ear function. Following active turning, feedback from reflexes elicited by vestibulospinal activity apparently dominates the perceptual experience. Practical consequences in medicine and aviation are discussed.

Adult↗
PubMed1975

Some effects of alcohol on various aspects of oculomotor control.

Recent studies have shown that alcohol interferes with visual control of vestibular nystagmus. The present study was designed to assess three partially independent systems of oculomotor control. Performance on three tasks was measured before and after mild alcohol dosage. One task involved visual suppression of vestibular nystagmus; a second involved smooth oculomotor tracking of a moving target; and a third required repetitive rapid voluntary shifts in gaze. Oculomotor control was degraded on the first two tasks with recovery toward the initial performance level 4 h after drinking. Performance on the third task was not obviously degraded, although it is possible that improvement with practice was retarded. Results are discussed in terms of neurological systems involved and kinds of flight tasks potentially affected.

Aerospace Medicine↗
PubMed1975

Disorientation phenomena in naval helicopter pilots.

The incidence of pilot disorientation in fixed- and rotary-wing aircraft has been previously investigated, but special orientation problems of naval helicopter pilots engaged in operations at sea and landing on moving platforms have not been previously investigated. A questionnaire concerning disorientations was answered anonymously and individually by 104 active naval helicopter pilots. Fifty-six percent indicated one or more espisodes of severe disorientation, and 8.6% indicated having experienced severe disorientation five or more times while piloting helicopters. A number of factors conducive to disorientation were identified. Some precipitating factors appear to be specific to operations over water or over a moving deck, although some of these may well have their counterparts in special operations over land. Other factors are common to fixed-wing as well as rotary-wing aircraft. A number of potential countermeasures for various precipitating factors are discussed.

Accidents, Aviation↗
PubMed1970

Response of semicircular canal dependent units in vestibular nuclei to rotation of a linear acceleration vector without angular acceleration.

1. Recent experiments have shown that rotation of a linear acceleration vector round the head can generate involuntary ocular nystagmus in the absence of angular acceleration. The present experiments examine the suggestion that adequate stimulation of the semicircular canals may contribute to this response.2. Decerebrate cats were located in a stereotaxic device on a platform, slung from four parallel cables, which could be driven smoothly round a circular orbit without inducing significant angular movement of the platform. This Parallel Swing Rotation (PSR) generated a centripetal acceleration of 4.4 m/sec(2) which rotated round the head at 0.52 rev/sec.3. The discharge frequency of specifically lateral canal-dependent neural units in the vestibular nuclei of cats was recorded during PSR to right and left, and in the absence of motion. The dynamic responses to purely angular motion were also examined on a servo-driven turntable.4. Without exception all proven canal-dependent cells examined (twenty-nine cells in nine cats) were more active during PSR in the direction of endolymph circulation assessed to be excitatory to the unit, than during PSR in the opposite direction.5. The observed changes in discharge frequency are assessed to have been of a magnitude appropriate for the generation of the involuntary oculomotor response induced by the same stimulus in the intact animal.6. The findings suggest that a linear acceleration vector which rotates in the plane of the lateral semicircular canals can be an adequate stimulus to ampullary receptors, though an explanation which invokes the modulation of canal cells by a signal dependent upon the sequential activation of macular receptors cannot be positively excluded.

Acceleration↗