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Country of Origin: The Netherlands Start: 01/12/04 Scientific Supervisor: Prof. P. Thier Job description: Mobility is a major hallmark of man and most other animal species. It underlies our ability to explore the world and to make pragmatic use of objects in the world. However, it also complicates perception of the world by breaking the simple relationship between sensation and perception. Motion vision may save as a case in point. The retinal image motion an observer experiences is in general the resultant of the movement of the visual object he is looking at in the external world and movements of his eyes, the carriers of the visual sensors, the retinae, relative to the world. While vestibularly or optokinetically driven reflexes can be used to stabilize the eyes relative to the world in cases of inadvertent head movements, thereby minimizing self-induced retinal image motion, these reflexes must be shut down if an active reorientation based on eye, head or body movements is needed. In such cases, perceiving the “true” visual motion of the world and of objects in the world requires filtering out the self-induced components of image motion on the retina. How is this possible and which parts of the brain contribute to this process which result in perceptual stability despite ego-motion. In order to come up with answers, we use a combined approach involving psychophysical, electrophysiological and functional imaging techniques in studies of healthy human subjects, patients with cortical or cerebellar disease as well as non-human primates. |