Spectral analysis of tachygastria recorded during motion sickness.

The purpose of the present experiment was to study frequency changes in gastric myoelectric activity of healthy human subjects and the development of symptoms of motion sickness as brought about by vection or illusory self-motion. Fifteen fasted healthy human subjects were seated inside a circular vection drum, the rotation of which produces visual signals of self-motion that are in conflict with vestibular signals (i.e., mismatched sensory input). An electrogastrogram was obtained for three 15-min. periods: baseline, rotation, and after drum rotation stopped. Respiration, symptoms volunteered by subjects, and a continuous measure of intensity of symptoms were recorded. Five subjects showed a continuation of normal 3-cycles/min. activity during drum rotation and reported no symptoms of motion sickness. Ten subjects showed a shift of their dominant gastric frequency from 3 cycles/min. to 4-9 cycles/min. during drum rotation and reported symptoms of motion sickness. Running spectral analysis revealed a close correspondence over time between tachygastria and reports of symptoms of motion sickness.