Visual-vestibular conflict induced by virtual reality in humans.

Conflicting inputs from visual and vestibular afferents produce motion sickness and postural instability. However, the relationship of visual and vestibular inputs to each other remains obscure. In this study, we examined the development of subjective sickness- and balance-related symptoms and objective equilibrium ataxia induced by visual-vestibular conflict (VVC) stimulation using virtual reality. The subjective symptoms evaluated by Graybiel's and Hamilton's criteria got gradually worse during the VVC. The objective postural instability was not observed during the VVC, but it occurred immediately after the VVC. There was a time lag between the subjective symptoms and objective ataxia induced by VVC. Our study suggests that the VVC inputs are processed in different pathways causing subjective autonomic symptoms and postural instability in humans.