ABSTRACT
PURPOSE: This study investigated the physiological correlates of motion sickness provoked by viewing an optokinetic rotating drum. METHOD: A total of 52 subjects viewed an optokinetic rotating drum for 16 min. Subjective symptoms of motion sickness (SSMS) and ratings of over-all sickness were measured during the drum rotation. Electrogastrogram (EGG), electroencephalogram (EEG), electrocardiogram, and skin conductance were measured as physiological correlates of motion sickness. RESULTS: Analysis by Pearson's correlation showed that the subjects who had higher scores of SSMS during the drum rotation generated the following: a) a higher rating of over-all sickness (r = 0.76); b) a higher ratio of spectral power of EGG at 4-9 cycles per minute (cpm) between drum rotation and baseline periods (r = 0.63); c) a higher net percent increase of spectral power in the EEG frequency band 0.5-4 Hz between drum rotation and baseline periods on C3 (r = 0.29) and C4 (r = 0.31); d) a higher ratio of spectral power of EEG frequency band 0.5-4 Hz between drum rotation and baseline periods on C3 (r = 0.31); and e) a higher level of net increase in skin conductance from baseline to drum rotation (r = 0.30). CONCLUSION: The increase of EGG at 4-9 cpm activity, gastric tachyarrhythmia, is the most sensitive physiological index of the severity of symptoms of motion sickness.
Subject(s)
Motion Sickness/physiopathology , Nystagmus, Optokinetic , Rotation , Severity of Illness Index , Visual Perception , Adolescent , Adult , Electrocardiography , Electroencephalography , Electromyography , Female , Galvanic Skin Response , Gastrointestinal Motility , Heart Rate , Humans , Male , Monitoring, Physiologic , Motion Sickness/classification , Motion Sickness/etiology , Motion Sickness/psychology , Regression Analysis , Sensitivity and SpecificityABSTRACT
Two experiments were conducted to observe the sensory hedonic responses and facial EMG activities elicited from different tastes. In Experiment 1, 25 subjects tasted flavors of apple juice, Gatorade, water, soybean milk, and pickle juice. In Experiment 2, 21 subjects tasted a sugar solution, a salt solution, and water. Subjects' sensory hedonic reports and facial EMG activity in the levator labii superioris/ alaeque nasi region were recorded in each experiment. The results from Experiment 1 showed that subjects reported significantly higher ratings of palatability to the apple juice, Gatorade, and water than to the soybean milk and pickle juice. The results from Experiment 2 indicated that the subjects reported significantly higher ratings of palatability to the water and sugar solution than to the salt solution. EMG recordings in both experiments showed that the negative hedonic sensations were associated with higher EMG activity in the levator labii muscle region, and that the positive hedonic sensations were associated with lower EMG activity in the same muscle region. It is concluded that facial EMG activity can be used as an indicator of palatability in humans.
