The dynamics of the vestibulo-ocular reflex after peripheral vestibular damage - II. Comparison with dynamics after optically induced learning

The vestibule-ocular reflex (VOR) stabilizes gaze adequately under a variet y of conditions because it is capable of a simple form of motor learning. L earning is induced by changed visual conditions or to compensate for vestib ular sensory loss, We asked whether the mechanisms that are triggered by vi sual signals can fully account for recovery from vestibular damage. We addr essed this question by comparing the effects of optically induced motor lea rning (i.e., changes in gain induced by telescopic lenses) and recovery fro m a unilateral horizontal canal plug on the dynamics of the cat VOR. Optica lly induced learning modified the gain of the VOR more effectively for rota tion at low frequencies (below 5 Hz) than for higher-frequency stimuli. Dur ing recovery from a plug, the gain of the VOR increased at all frequencies tested, with a similar time course for all frequencies. After recovery the gain for rotation at 5 Hz or above was relatively enhanced. After recovery reached its upper limit, optically induced learning could bring about furth er changes in gain. The results are interpreted with respect to partially ( but not completely) shared mechanisms for optically induced learning and re covery after a unilateral canal plug.