How changes in vestibular and visual reference frames combine to modify body orientation in space.

The aim of this study was to analyse how changes in vestibular and visual reference frames combine to modify body orientation in space, and to determine the relationship between postural, oculomotor and perceptive parameters. Changes in vestibular and visual references were investigated by comparing controls and vestibular defective patients (Ménière's patients tested before and one week after unilateral vestibular nerve section) under three visual contexts (light with and without vertical and horizontal coordinates, darkness). Unilateral vestibular loss was responsible for postural and perceptive deviations whose direction depended on the presence of visual reference frame. We suggest these changes vary according to the spatial reference frame patients are based on. Postural changes were related to perceptive modifications but not to eye cyclotorsion.