Somatosensory compensation for loss of labyrinthine function.

Somatosensory compensation for vestibular deficiency was demonstrated by stepping in circles in the dark. Stepping around in small circles provides a complex pattern of afferent somatosensory signals, which in combination represent the actual movement. Labyrinthless patients, i.e. patients devoid of labyrinthine function, reported during real as well as during apparent stepping around (on a rotating platform without stimulation of the canals) a strong sensation of rotation, as did the healthy subjects; they had a stronger somatosensory nystagmus than the healthy controls. In controls, the somatosensory and vestibular aftersensations cancelled, while the vestibular slightly outweighed their somatosensory afternystagmus . Labyrinthless subjects had no vestibulo- culomotor integrator function.