Vestibule-ocular reflex modification after virtual environment exposure

Immersion in an illusory world is possible by means of virtual reality (VR) , where environmental perception is modified by artificial sensorial stimul ation. The application of VR for the assessment and rehabilitation of patho logies affecting the vestibular system, in terms of both diagnosis and care , could represent an interesting new line of research. Our perception of re ality is in fact based on static and dynamic spatial information perceived by our senses. During head movements in a virtual environment the images on the display and the labyrinthine information relative to the head angular accelerations differ and therefore a visuo-vestibular conflict is present. It is known that mismatches between visual and labyrinthine information may modify the vestibulo-oculomotor reflex (VOR) gain. We studied the post-imm ersion modifications in 20 healthy subjects (mean ape 25 years) exposed to a virtual environment for 20 min by wearing a head-mounted display. VOR gai n and phase were measured by means of harmonic sinusoidal stimulation in th e dark before, at the end of and 30 min after VR exposure. A VOR gain reduc tion was observed in all subjects at the end of VR exposure which disappear ed after 30 min. Our data show that exposure to a virtual environment can i nduce a temporary modification of the VOR gain. This finding can be employe d to enable an artificial, instrumental modification of the VOR gain and th erefore opens up new perspectives in the assessment and rehabilitation of v estibular diseases.