Vestibular compensation revisited.

Vestibular compensation for the static and dynamic disorders induced by unilateral labyrinthectomy is a good model of plasticity in the central nervous system. After the lesion, the static deficits generally disappear in a few days, whereas recuperation of the dynamic, vestibular-related synergies is much slower and merely partial. The goal of this article is to reexamine some aspects of vestibular compensation in light of several recent findings. In the first part, we show that in vertebrates the organization of the neural networks underlying vestibular reflexes is deeply linked with the skeletal geometry of the animals. Accordingly, we propose that the neuronal mechanisms underlying vestibular compensation might be plane specific. We then deal with several issues related to the exact timing of vestibular compensation in various species. In the second part, we give several examples showing that vestibular compensation can now be studied at the molecular and cellular levels. For instance, we summarize some of our recent data, which indicate that glial cells could be strongly involved in the compensation process.