Prevention Of Overt Motion Sickness By Incremental Exposure To Otherwise Highly Stressful Coriolis Accelerations
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Prevention of Overt Motion Sickness by Incremental Exposure to Otherwise Highly Stressful Coriolis Accelerations
Four Navy enlisted men were exposed in a slow rotation room (SRR) by stepwise increases over a period of 16 days to a terminal velocity of 10 rpm. The fact that overt symptoms of motion sickness at 10 rpm were prevented solely by the incremental increases demonstrated that adaptive processes somehow inhibited irradiation of vestibular activity to cell assemblies in areas concerned in the genesis of symptoms. The SRR sickness observed in other subjects suddenly exposed to 10 rpm thus may result from failure of homeostatic processes, permitting such irradiation. The underlying processes therefore are clearly nonhomeostatic in nature and produce a nonhomeostatic state. The findings have practical as well as theoretical implications. (Author).
Progressive Adaptation to Coriolis Accelerations Associated with 1-rpm Increments in the Velocity of the Slow Rotation Room
The purpose of this experiment was to answer specific questions relating to the design of an adaptation schedule effective in protecting against motion sickness in a rotating environment. Ten men with normal vestibular function executed controlled head and body movements at each of ten 1-rpm step increase in the velocity of the Pensacola Slow Rotation Room. On the completion of every moment, subjects were required to indicate whether or not they had detected sensations of vestibular or somatosensory origin. At each velocity step, the movements were continued until each of 24 consecutive movements had elicited a negative response and the subject was judged to be symptom free. When this arbitrary adaptation criterion was reached, the angular velocity was increased by 1 rpm and the procedure repeated. On attaining the criterion at the terminal velocity (10 rpm), the rotation was stopped and the postrotatory phenomena were investigated using the same techniques. The principal finding was that the number of movements necessary to achieve the adaptation criterion was systematically related to the absolute level of angular velocity. Considerably more head and body movements were required to reach the same level of adaptation at faster speeds than at slower speeds, even though the size of the step increment remained constant. There was some evidence to indicate that the amount of stimulation to criterion depended upon the initial magnitude of sensation elicited by the increment. There were also wide individual differences in both the rate of adaptation and the minimum velocity necessary to evoke sensation. (Author).
Motion Sickness Susceptibility Under Weightless and Hypergravity Conditions Generated by Parabolic Flight
Motion sickness susceptibility of five labyrinthine-defective (L-D) and 25 normal subjects was tested under the force environments encountered in parabolic flight (0 g and hyper-g). The L-D subjects were uniformly symptomless, while the normal subjects revealed great inter- and intra-individual differences in susceptibility to motion sickness provoked by standardized head movements during: (1) the hypergravic and (2) the weightless phases of the parabolic maneuver while restrained; and (3) the weightless phase while being rotated in a chair. Four of six subjects tested under condition 1 were completely unaffected by the condition while two reacted with symptoms. Condition 2 provoked severe symptoms in five of the twelve subjects tested and moderate symptoms in one. Fifteen subjects tested under condition 3 revealed either a marked increase or decrease in susceptibility to Coriolis acceleration in weightlessness compared to terrestrial baseline measurements. (Author).