ALTERATIONS IN R-R VARIABILITY ASSOCIATED WITH EXPERIMENTAL MOTION SICKNESS

Motion sickness is a complex integration of responses from multiple ph ysiological systems. Whether the changes that occur during the time co urse of motion sickness are mediated by the sympathetic or parasympath etic systems is still controversial. The present study evaluates alter ations in R-R variability during experimental motion sickness in motio n sick and non-motion sick subjects. Ten motion sick subjects and 7 no n-motion sick subjects participated in the study. Power spectrum analy sis of R-R variation was conducted for all subjects 10 min before a br ief vestibular disorientation test (BVDT), for 5-10 min of the test, a nd 10 min after the test. Subjects were also asked to report their sym ptoms during the test. The motion sick group showed a significant redu ction in the power spectrum density of the R-R interval at the mid and high frequencies during the BVDT test period (BVDT), in comparison wi th the rest period (Rest). These changes probably indicate a decrease in parasympathetic activity during the time course of motion sickness, The non-motion sick group did not show significant differences at any of the frequencies during BVDT Power spectrum analysis of the R-R int erval provides an objective measure of the autonomic response to exper imental motion sickness. (C) 1997 Elsevier Science B.V.