The retention of adaptation to motion sickness eliciting stimulation

Purpose: This study compared the retention of adaptation to motion sickness eliciting stimulation after 1 mo and 1 yr. Method: A total of 34 subjects who developed nausea to an optokinetic rotating drum in a preliminary session repeatedly viewed the same rotation with an interval of 48 h between sessions until they had no feelings of nausea. For each session, subjects' electrogastrograms (EGCs) at 4-9 cycles per minute (cpm) were also recorded as a physiological index of the severity of motion sickness. Subjects were re-exposed to the optokinetic drum either after 1 mo or 1 yr. Results: The mean ratings of nausea for the subjects who were re-exposed to the optokinetic drum after 1 mo were 9.23 for the initial exposure and 0.94 for the re-exposure session. EGG indicators of motion sickness were 6.65 for the initial exposure and 1.03 for the re-exposure session. The mean ratings of nausea for the subjects who were re-exposed to the optokinetic drum after 1 yr were 8.94 for the initial exposure and 6.88 for the re-exposure session. ECC indicators of motion sickness were 5.97 for the initial exposure and 4.05 for the re-exposure session. Conclusion: These results indicated that adaptation to the motion sickness eliciting stimulation of optokinetic rotation is almost completely retained for 1 mo and partially retained for 1 yr.