THE VESTIBULAR SYSTEM AS A MODEL OF SENSORIMOTOR TRANSFORMATIONS - A COMBINED IN-VIVO AND IN-VITRO APPROACH TO STUDY THE CELLULAR MECHANISMS OF GAZE AND POSTURE STABILIZATION IN MAMMALS

To understand the cellular mechanisms underlying behaviours in mammals , the respective contributions of the individual properties characteri zing each neuron, as opposed to the properties emerging from the organ ization of these neurons in functional networks, have to be evaluated. This requires the use, in the same species, of various in vivo and in vitro experimental preparations. The present review is meant to illus trate how such a combined in vivo-in vitro approach can be used to inv estigate the vestibular-related neuronal networks involved in gaze and posture stabilization, together with their plasticity, in the adult g uinea-pig. Following first a general introduction on the Vestibular sy stem, the second section describes various in vivo experiments aimed a t characterizing gaze and posture stabilization in that species. The t hird and fourth parts of the review deal with the combined in vivo-in vitro investigations undertaken to unravel the physiological and pharm acological properties of vestibulo-ocular and vestibule-spinal network s, together with their functional implications. In particular, we have tried to use the central vestibular neurons as examples to illustrate how the preparation of isolated whole brain can be used to bridge the gap between the results obtained through in vitro, intracellular reco rdings on slices and those collected in vivo, in the behaving animal. (C) 1997 Elsevier Science Ltd.