Vestibulo-ocular reflexes are essential components in the perception and control of spatial orientation. They are also important for the perception of the visual world, as well as visually-guided behavior, since we view the world from a constantly shifting platform and certain visual mechanisms function optimally only if the images on the retina are relatively stable. As we go about our everyday activities, visual and vestibular mechanisms help to stabilize our gaze on objects of interest, by generating eye movements that offset our head movements. The traditional approach emphasized mechanisms that deal with rotational disturbances. More recently, however, it has become clear that a separate class of vestibulo-ocular reflexes exists (Translational VORs or TVORs) that represent a phylogenetically recent acquisition in the evolutionary tree and which appear to have evolved in parallel with foveal vision, vergence eye movements and stereopsis. This proposal is a competitive renewal to test specific hypotheses about how sensory information is centrally processed in order to create motor commands for the TVOR. We propose novel behavioral experiments aiming at understanding specific functional hypotheses about the TVOR, as well as neurophysiological studies to understand the yet unknown neural processing. Electrophysiological data will be closely accompanied with theoretical modeling in order to delineate the vestibulo-ocular computations that underlie the organization of the complex oculomotor responses during translation. Although motivated by fundamental basic science issues, the results of this effort will provide a basis for understanding clinical deficits related to otolith system pathology and for the development of clinical tests of otolith and vestibulocerebellar function. ? ?
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