On the role of vestibulo-ocular reflex plasticity in recovery after unilateral peripheral vestibular lesions.

Although adaptive plasticity is a well-known feature of the vestibulo-ocular reflex (VOR), deficits in VOR performance after unilateral labyrinthectomy are poorly compensated in a large percentage of cats. To assess whether VOR plastic capabilities are affected by labyrinthectomy, forced oscillation in front of a patterned surround was imposed in unilaterally labyrinthectomized cats. This experimental paradigm has been shown to be very effective in inducing adaptive VOR gain changes in intact animals. We demonstrate that plasticity of VOR gain is still present both in acute and chronic stages following vestibular lesions. By contrast, forced oscillation did not significantly alter the lesion-induced asymmetry of responses. We conclude that VOR gain control mechanisms are not used to their fullest possible extent in a large percentage of animals suffering unilateral vestibular damage.