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Biomedical subjects

A Graybiel

Publications and source records attributed to A Graybiel.

At least 55 records · Page 3Linked to original sources
PubMed1978

Some influences of touch and pressure cues on human spatial orientation.

During constant velocity rotation about his recumbent Z axis, a blindfolded subject feels as if he were on an orbital path in the same direction. This experienced motion results from the pattern of touch and pressure stimulation of the body surface. If the subject changes the pressure pattern on his body by bracing himself in the rotating apparatus in different ways, it is possible for him to influence profoundly and systematically his apparent orientation. For example, pressure on the top of his head while he is rotating can make the subject feel he is upside down on a cylindrical path. The changes in apparent ongoing posture elicited by different patterns of pressure cues are very similar for different subjects and are constant for the same subject over time. During experienced orbital motion, a subject will hear a continuously emitting sound source--one that is stationary in the external environment--as circling his head in the direction opposite that of his true rotation. If the rotating subject is permitted unrestricted sight of his surroundings, he neither experiences orbital motion nor mislocalizes sounds. These observations provide insight into the spatial orientation mechanisms that normally allow an organism to distinguish accurately between those changes in activity at its receptors contingent on its own movements, and those resulting from movement within the environment. They also provide a way of understanding some of the postural illusions experienced during exposure to unusual force environments, including free fall.

Adolescent↗
PubMed1978

Prevention of motion sickness in flight maneuvers, aided by transfer of adaptation effects acquired in the laboratory: ten consecutive referrals.

Ten flyers, grounded because of nausea and vomiting, were referred as potential candidates for adaptation to cross-coupled angular accelerations in a slow-rotation room; such adaptation has been shown to "transfer" to flight maneuvers. There was no opportunity to attempt treatment in two candidates. Among the remaining eight, five regained flight status (62.5%); follow-up periods of those five candidates ranged from 10 to 27 months. In one of the three remaining candidates, a satisfactory level of adaptation was achieved but more than 4 months elapsed before his assignment to a duty squadron. After becoming sick in his first flight (F-104), he submitted a request to be removed from duty involving flying. In the remaining two candidates, the rate of their acquisition of adaptation not only was very slow but also, after leveling off, actually declined. In other words, poor as well as good performance is demonstrable in the slow-rotation room.

Adaptation, Physiological↗
PubMed1978

Longevity in military pilots: 37-year followup of the Navy's "1000 aviators".

The 37-year nonmilitary mortality rate for initially healthy aviators was determined in a followup program on the U.S. Navy's "1000 Aviator" cohort. Of the 800 survivors of World War II and the Korean conflict, 95 were found to have died from nonmilitary causes over this followup period. This is markedly less than the 208 that would be expected from a random sample of white American men over a similar period (p less than 0.005). It is also significantly less than the 143 that would have been expected from a group of men who had passed an initial insurance physical (p less than 0.005). Lower-than-expected death rates occurred in all three major categories of cause of death in this age group: cardiovascular, neoplastic, and accidental. The generally good socioeconomic background, the positive genetic influence of long-lived parents, the above average intelligence, and the health and fitness orientation of the military aviator are all thought to be factors contributing to this increased longevity.

Accidents↗
PubMed1977

Comparison of susceptibility to motion sickness during rotation at 30 rpm in the earth-horizontal, 10 degrees head-up, and 10 degrees head-down positions.

Normal persons rotated about an Earth-horizontal axis vary in their susceptibility to motion sickness. The purpose of this experiment was to measure, intraindividual differences in susceptibility in 12 subjects when rotated 10 degrees head up and 10 degrees head down as well as in the horizontal position. Subjects assumed the test-position 60 min prior to rotation, thus providing an opportunity for translocation of body fluids. Physiological and psychophysical measurements were conducted throughout the experiment. There were no intraindividual differences in susceptibility to motion sickness in the three positions tested, although there were significant differences in vital capacity, demonstrating the expected fluid shifts. It was concluded that, in the sample of subjects tested, short-term effects of fluid shifts greater than those that would be manifested in zero gravity had no definite effect on motion sickness susceptibility.

Adult↗
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↗
PubMed1976

The prevention of motion sickness in orbital flight.

A question has arisen whether zero gravity qualifies as just another "motion environment" in which motion sickness may be elicited, or if one or more undetermined etiological factors are present which render such terms as "motion environment" and "motion sickness" inappropriate. The question is of more than academic interest for the reason that in the forthcoming Shuttle Program we have either one problem or two: one if we are concerned solely with prevention, but two if we must tackle the problem of covert etiological factors as well. This problem points up the need to define motion sickness if investigators, world-wide, hope to resolve the matter in the most economical manner. Meanwhile, substantial reliance must be placed on the use of antimotion sickness drugs and some recent findings are presented based on tests carried out in a rotating room using a new procedure. Whereas previous findings in our laboratory dealt with group responses, the new findings are not only valid for a group, but also valid for each subject tested. It was demonstrated that the effects of a drug may be efficacious for a group yet may be detrimental for one or more individuals in that group.

Aerospace Medicine↗
PubMed1976

Prevention of experimental motion sickness by scopolamine absorbed through the skin.

A double-blind placebo-controlled study compared the efficacy of the antimotion sickness drug scopolamine when administered by oral or transdermal routes. A secondary purpose was to extend our bioassay involving fixed-dose combinations of the homergic drugs promethazine and ephedrine. After receiving 12 apparently identical drug-placebo treatments, eight normal male students were exposed to a slow rotation room to stressful accelerations generated by their execution of 40 head movements out of the plane of the room's rotation of 1 rpm and at 1-rpm increments until either symptoms were experienced (just short of frank motion sickness) or the 27-rpm ceiling on the test was reached. Efficacy of a drug was defined in terms of the placeborange and categorized as beneficial, inconsequential, or detrimental. The rank order of drugs with beneficial effects was: 1) promethazine 25 mg plus ephedrine 12.5 mg (86%); 2) scopolamine by mouth (75%); 3) scopolamine transdermally (63%); and 4) promethazine 12.5 mg plus ephedrine 25 mg (29%). The only detrimental effect was with scopolamine given orally. It is concluded that the advantages of the transdermal scopolamine, which include minimal side effects and prolonged effectiveness, deserve full exploitation.

Administration, Topical↗
PubMed1976

Sopite syndrome: a sometimes sole manifestation of motion sickness.

Drowsiness is one of the cardinal symptoms of motion sickness; therefore, a symptom-complex centering around "drowsiness" has been identified which, for convenience, has been termed the sopite syndrome. Generally, the symptoms characterizing this syndrome are interwoven with other symptoms but under two circumstances the sopite syndrome comprises the main or sole overt manifestation of motion sickness. One circumstance is that in which the intensity of the eliciting stimuli is closely matched to a person's susceptibility, and the sopite syndrome is evoked either before other symptoms of motion sickness appear or in their absence. The second circumstance occurs during prolonged exposure in a motion environment when adaptation results in the disappearance of motion sickness symptoms, except for responses characterizing the sopite syndrome. Typical symptoms of the syndrome are: 1) yawning, 2) drowsiness, 3) disinclination for work, either physical or mental, and 4) lack of participation in group activities. Phenomena derived from an analysis of the symptomatology of the sopite syndrome are qualitatively similar but may differ quantitatively from abstractions derived in other motion sickness responses. One example is the sometimes unique time course of the sopite syndrome. This implies that the immediate eliciting mechanisms not only differ from those involved in evoking other symptoms, but, also, that they must represent first order responses. Diagnosis is difficult unless the syndrome under discussion is kept in mind. Prevention poses a greater problem than treatment.

Adolescent↗
PubMed1976

A Z-axis recumbent rotating device for use in parabolic flight.

A prototype apparatus for exposing persons to rotation about their Z-axis in parabolic flight is described. Although it resembles Earth-horizontal axis devices, added features are its strength and portability, and the fiber glass "couch" with adjustable elements providing support and restraint. Even under ground-based conditions, this device provides unique opportunities for investigations involving not only canalicular and macular mechanoreceptors, but also touch, pressure, and kinesthetic receptor systems.

Humans↗
PubMed1975

Human assay of antimotion sickness drugs.

The present study was undertaken to improve previous testing procedures, involving the use of a slow rotation room, for assessing the efficacy of antimotion sickness drugs which had validity for groups of subjects but not for each individual in the group. Three major changes were introduced: first, the use of an incremental increase in the intensity of the stressful stimuli of constant intensity; second, a systematic distribution of placebos, rather than a random distribution, in using a modified Latin-square design; third, categorizing the responses as "inconsquential," "beneficial," and "detrimental"--the range of the "placebo responses" was doubled to define the inconsequential range and response above or below were, respectively, beneficial or detrimental. Only drugs known to have antimotion sickness effectiveness were tested and the cardinal findings can be briefly summarized: 1) The group responses were similar to the data previously reported; 2) Great individual differences in response to antimotion sickness drugs were revealed, implying that individual assessments must be made for maximal benefits; 3) The fixed-dose combination of promethazine hydrochloride and ephedrine sulfate (25 mg each) proved to be outstanding as this combination of homergic drugs clearly exhibited a suprasummation effect; and 4) A few tests were conducted using larger than usual doses and the results supported previous findings that, for a maximal beneficial effect in response to a single dose, individuals may vary both with regard to the choice of drug and the amount administered.

Adult↗