Haptic foundations for visually guided action

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Karl, Jenni M.
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Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience.
Prehension is proposed to consist of two movements mediated by separate neural pathways – a Reach transports the hand to the target while a Grasp shapes the hand for target purchase – but under vision the two movements appear as a seemless act. The purpose of the present thesis was to examine prehension under conditions of limited visual feedback. Removing vision in adults caused prehension to decompose into an open handed Reach followed by a haptically mediated Grasp, suggesting that haptics also access the Reach and Grasp pathways. That Grasp, but not Reach, formation is equally accurate under haptic versus visual control indicates that the sensory control of the two movements can be differentiated. Finally, young infants perform haptic Reach and Grasp movements before integrating them together under vision. These results suggest that the Reach and the Grasp, with their requisite neural pathways, originate under haptic control with secondary access by vision.
haptic control , neural pathways , prehension , Reach and Grasp , visual control , visual feedback