コリオリ刺激で誘発される眼球運動と動揺病症状の研究

Abstract

Coriolis stimulation evokes severe motion sickness, accompanied by various eye movements, auotonomic nervous symptoms and disorders of spatial orientation. In this study, we performed 2 experiments to evaluate the relationship between the severity of motion sickness and eye movement response to Coriolis stimulation as well as the relationship between disorders of spatial orientation and eye movements and to elucidate the mechanism that generates Coriolis-induced eye movements.Experiment 1 was performed on 12 subjects ranging in age from 20 to 34 years. Eye movements were recorded by a CCD view camera and electronystagmogaphy when subjects tilted their heads on a rotating chair (120°/sec) in invisible surroundings. As regards autonomic nervous symptoms and disorders of spatial orientation during stimulation, there was a great variation in susceptibility among 12 subjects. Disorders of spatial orientation induced by abnormal inputs of Coriolis stimulation, evoked eye movements and autonomic nervous symptoms. While spatial orientation continued to be influenced by Coriolis stimulation, autonomic nervous symptoms, which functioned as an alarm against disorientation, became severe.In experiment 2, the subject first tilted his head, backward and forward repeatedly, and then, leftward and rightward repeatedly. We analyzed eye movements under these two conditions. While forward and backward tilting head movements evoked torsional eye movements, leftward and rightward tilting head movements evoked vertical eye movements. The axis of eye rotation vector induced by Coriolis stimulations accorded closely with the direction of acceleration vector generated by head tilting and was well explained by vector analysis.