Biphasic Response of Autonomic Nervous System to Visually-Induced Motion Sickness

Abstract

To quantitatively assess the effect of visually-induced motion sickness, a swaying motion picture was shown to 55 subjects, and their maximum cross-correlation coefficient (ρmax) between Mayer wave-related component in blood pressure variability and that in heart rate variability was analyzed. The physiological index ρmax reflects the state of baroreflex function governed by the autonomic nervous system. In the case of the subject group with extremely high total score in the simulator sickness questionnaire (SSQ), the decrease in ρmax could be observed at two positions in time, i.e., around one minute and around ten minutes after the beginning of presentation. Such biphasic response can lead to the hypothesis that the symptom caused by visually-induced motion sickness can be divided into two parts: the reflective response to avoid the unpleasant visual image and the cumulative symptom corresponding to feeling of sickness. To verify this hypothesis, an unpleasant video film including surgical operation and no swaying scenes was presented to the same subjects. The comparison between the swaying video and the unpleasant video showed that the responses of ρmax were partly similar to each other in the case of the subject group with high self-evaluated susceptibility to motion sickness.