VESTIBULAR COMPENSATION REVISITED

Vestibular compensation for the static and dynamic disorders induced b y unilateral labyrinthectomy is a good model of plasticity in the cent ral nervous system. After the lesion, the static deficits generally di sappear 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 li ght of several recent findings. In the first part, we show that in ver tebrates 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 vestib ular compensation might be plane specific. We then deal with several i ssues related to the exact timing of vestibular compensation in variou s species. In the second part, we give several examples showing that v estibular compensation can now be studied at the molecular and cellula r levels. For instance, we summarize some of our recent data, which in dicate that glial cells could be strongly involved in the compensation process.