Behavioral and modeling studies of eye and head coordination

Moving eyes and head to orient the visual axis to a point of interest is a routine movement for foveate animals. From reading a book to driving a car or playing tennis, we constantly have to change our line of sight in relation with the current activity. At first, the brain must analyze the visual environment to extract the main features linked to the needs of the task. Once the information is extracted and the goal computed, the central nervous system has to control and coordinate adequately the movements of several body parts (eye, head, trunk, etc.) to achieve accurately the task: modify the orientation of the visual axis. This thesis addresses different questions linked to the control of the gaze (gaze = head-in-space + eye-in-head) and the coordination of eye and head movements. Two methodologies were used throughout the thesis to help answering those questions. A first approach used behavioral experiments to generalize previously reported observations, from head-restrained to head-unrestrained condition. In this part, we first studied how human subjects take into account their own movements to update their internal representation of the spatial surroundings. Then we studied how they coordinate eye and head movement while tracking an oscillating target. The second approach was based on novel mathematical models of the head-unrestrained control of movements. The models were developed either to find a consensus about fundamental questions of eye-head coordination or to stress the importance of taking into account the delays of the sensory system in the control.(FSA 3) -- UCL, 201