Study of Vestibular Maladaptation under Visual-vestibular Conflict

点击翻译按钮获取中文摘要

1. Walking while wearing horizontally reversing goggles induced apparent motion sickness, which severity was affected not only by individual susceptibility, but also by surrounding situations. In addition, onset of motion sickness was often accompanied with equilibrium ataxia.2. Since vertically reversed vision, in contrast, did not evoke motion sickness, we must say that a mismatch between visual and vestibular inputs-alone does not evoke motion sickness, but a failure to detect spatial orientation which resulted from mismatched sensory inputs produced motion sickness.3. To objectively show equilibrium ataxia when motion sickness occurred, we examined normal subjects with Graybiel's ataxia test battery, before putting on the goggles, during walking while wearing the goggles and after finishing walking. A significant decrease in the score was found in the case of horizontally reversed vision. However, the degree of equilibrium ataxia did not correlate with the severity of autonomic nervous symptoms.4. Two patients with bilateral labyrinthine loss, one congenital, the other acquired, were examined in the same way. Although both patients similarly did not exhibit motion sickness symptoms, they showed quite different patterns of locomotion and equilibrium ataxia. Whereas a patient with congenital inner ear anomalies could walk well. even while wearing horizontally reversing goggles, the other patient. who lost labyrinthine functions due to Streptomycin intoxication presented moderate to severe ataxia under both situations, especially under wearing horizontally reversing goggles. Based on all these results, we devised, a new hypothesis which infers top-down regulation of the vestibular system called "Spatial Coordinates Hypothesis".