PHYSIOLOGICAL AND BEHAVIORAL-EFFECTS OF TILT-INDUCED BODY-FLUID SHIFTS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 54  (5) , 402-409
Abstract
The fluid shift theory of space motion sickness was discussed. An attempt was made to develop procedures to assess individual differences in response to rostral body fluid shifts on earth. Experiment 1 examined inner ear fluid pressure changes during head-down tilt in intact human beings. Tilt produced reliable changes. Differences among subjects and between ears within the same subject were observed. Experiment 2 examined auditory threshold changes during tilt. Tilt elicited increased auditory thresholds, suggesting that sensory depression may result from increased inner ear fluid pressure. Additional observations on rotation magnitude estimation during head-down tilt, which indicate that rostral fluid shifts may depress semicircular canal activity, are briefly described. Apparently, the inner ear pressure and auditory threshold shift procedures could be used to assess individual differences among astronauts prior to space flight. Results from the terrestrial observations could be related to reported incidence/severity of motion sickness in space and used to evaluate the fluid shift theory of space motion sickness.

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