Christophe Bourdin

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Using galvanic vestibular stimulation (GVS), we tested whether a change in vestibular input at the onset of goal-directed arm movements induces deviations in arm trajectory. Eight head-fixed standing subjects were instructed to reach for memorized visual targets in complete darkness. In half of the trials, randomly-selected, a 3 mA bipolar binaural galvanic(More)
OBJECTIVE To determine the effect of modifying the stable visual anchor on the postural stability of older individuals. The visual anchor was changed by opening doors similar to those found in an elevator cage. Lighting intensities inside and outside the cage were varied to create increasing or decreasing luminosity conditions. The effect of adding a(More)
The purpose of the present experiment was to investigate the extent to which subjects can perceive, at very slow velocities, an angular rotation of the support surface about the medio-lateral axis of the ankle, knee, hip, or neck joint when visual cues are not available. Subjects were passively displaced on a slowly rotating platform at .01, .03, and .05(More)
The present study compared the contribution of visual information of hand and target position to the online control of goal-directed arm movements. Their respective contributions were assessed by examining how human subjects reacted to a change of the position of either their seen hand or the visual target near the onset of the reaching movement. Subjects,(More)
Online visual control of the direction of rapid reaching movements was assessed by evaluating how human subjects reacted to shifts in seen hand position near movement onsets. Participants (N=10) produced saccadic eye and rapid arm movements (mean duration = 328 ms) towards a peripheral visual target in complete darkness. During the saccade, visual feedback(More)
The present study tested whether vestibular input can be processed on-line to control goal-directed arm movements towards memorized visual targets when the whole body is passively rotated during movement execution. Subjects succeeded in compensating for current body rotation by regulating ongoing arm movements. This performance was compared to the accuracy(More)
We investigated the possibility of controlling reaching movements on the sole basis of central mechanisms, i.e., without peripheral feedback on hand and target positions. A deafferented subject (GL) and control subjects reached with the unseen hand for a straight-ahead target that could be displaced laterally at movement onset. The shifted target was(More)
Because our environment and our body can change from time to time, the efficiency of human motor behavior relies on the updating of the neural processes transforming intentions into actions. Adaptation to the context critically depends on sensory feedback such as vision, touch or hearing. Although proprioception is not commonly listed as one of the main(More)
Seated observers requested to detect low-velocity passive rotations show a high motion-detection threshold. However, when standing on a slowly rotating platform, their equilibrium is preserved, suggesting that cognitive sensing and sensorimotor reactions do not share the same central processes. The present experiments investigated the ability of observers(More)