Rehabilitation following brain damage: some neurophysiological mechanisms. Functional recovery in the visual and...

The visual and labyrinthine sensing systems are often neglected in the rehabilitation process of patients with central nervous system (CNS) lesions. Nevertheless, their integrity is essential for the construction of motor tasks ranging from accurate reaching to the co-ordinated behaviours of posture and locomotion. This tasks may be influenced considerably by the roles of the visual and vestibular systems in the perceptual analysis of localizing objects in space ("egocentric localization") and of spatial orientation of the body ("ego-orientation") and in controlling oculomotor and postural stability. The anatomy, physiology, clinical relevance and patterns of recovery of function of two specific visual-vestibular related behaviours is addressed, namely ocular stability and egocentric localization. Emphasis is placed upon such issues as (a) motor learning in complete and incomplete lesions as adjudged from observations of peripheral vestibular nerve disorders; (b) the role of the cerebellum in calibrating motor performance with particular reference to the modifiability of the vestibulo-ocular reflex to attain ocular stability; (c) the use of redundant or complementary structures as assumed from evidence of recovery from chronic visual field deficits; and (d) specified behavioural tactics as a mechanism for adaptation.