Vestibular compensation: role of visual motion cues in the recovery of posturo-kinetic functions in the cat.
Vision has long been recognized as a sensorimotor system which plays a major role in substitution for functional deficits induced by unilateral or bilateral exclusion of primary vestibular afferents. Little is known, however, about the post-lesion influence of visual inputs on the recovery of posturo-kinetic balance in a situation where fine, well-coordinated locomotor adjustments are required. The present study was carried out in order to gain some insight into the role played by motion vision in the restoration of fine posturo-kinetic balance in adult cats subjected to unilateral vestibular neurectomy. Prior to the lesion, 15 adult animals were trained to cross a beam rotating at various speeds. Their best global balance performance (highest beam rotation speed that did not provoke falling) and their average locomotion speed were evaluated. After the lesion, the cats were separated into three groups: (1) five animals were placed in a normal environment (animal house) (NV cats); (2) four animals were exposed to stroboscopic illumination which eliminated visual motion cues (SV cats) for 2 weeks following the lesion; and (3) three animals were placed in a normal environment and their training was interrupted for the same period as in the SV cats (NVI cats). The possible influence of the 2-week deprivation of visual motion cues on posturo-kinetic balance was also examined in three intact cats. The present behavioral study showed that: (1) early sensory deprivation caused suspension of the posturo-kinetic balance recovery process as long as it was maintained; (2) complete restoration of global balance capacities developed following the vestibular neurectomy after a significant delay in half of the SV cats; (3) the lack of motion cues resulted in severe alterations of fine posturo-kinetic balance (inappropriate dynamic motor adjustments and irregular locomotion speed regulation) in all SV cats; and (4) the visual deprivation induced a 2-week delay in the restoration of fine locomotor balance. These findings provide evidence for a defect in the visual sensory substitution processes that normally take place within the first few weeks following exclusion of primary vestibular afferents.
Zennou-Azogui
Y
Y
Laboratoire de Neurobiologie des Restaurations Fonctionnelles, Université de Provence, Marseille, France.
Xerri
C
C
Leonard
J
J
Tighilet
B
B
D000818:Animals; D002415:Cats; D003463:Cues; D003714:Denervation; D005260:Female; D008124:Locomotion / Q000502:physiology*; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D011187:Posture / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology; D014722:Vestibule, Labyrinth / Q000502:physiology*