• The vestibular organs sense head motion: canals sense rotation; otoliths sense linear acceleration (including gravity). • The central vestibular system distributes this signal to oculomotor, head movement, and postural systems for gaze, head, and limb stabilization.. • The visual system complements the vestibular system. • Visuo-vestibular conflict causes acute discomfort. • Peripheral and brainstem vestibular dysfunction causes pathological sense of self-motion and visuo-vestibular conflict.