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Abstract : Despite extensive research in the field of motor control, it is still not fully understood how visual and proprioceptive information related to hand and target positions are used to plan and control goal-directed arm movements. We developed an original method to investigate the online control of movement. In each of the studies realised, adult participants were asked to reach as accurately as possible visual targets. Modifications of either target position or seen hand position were triggered randomly, near movement initiation, and we analysed the kinematics of the rapid reaching movements. To reduce the putative role of cognitive, high-level processes on the online control of movement, we produced these perturbations such that they were not perceived by the subjects (i.e. these were never able to report verbally such events). Study 1 demonstrated that visual information of target position was taken into account earlier and greater compared to visual information of hand position to control in real time the rapid reaching movements. The limited use of hand visual feedback in this study appeared to be conflicting with a number of reports which emphasized its crucial contribution to the control of aimed arm movements. A detailed analysis of the literature suggested that the nature of the task, essentially a task where movement amplitude had to be controlled, could be responsible for the limited processing of visual information. The second study was designed to examine the use of hand visual feedback in the online control of rapid reaching movements, when only movement direction has to be controlled. Study 2 highlighted the ability of the nervous system to process rapidly and accurately visual and proprioceptive information on hand position. Indeed, visual information was used significantly and consistently, a result differing strikingly from that in the first study. It then appeared interesting to investigate the online control of reaching movements when modifications of hand visual feedback should affect both movement amplitude and direction. The underlying question was to know whether the online control of both components would be identical to what was observed in the two previous studies or whether we would observe an interaction-type effect ? Study 3 showed that the directional control of rapid movements on the basis of hand visual feedback is limited by the control of movement amplitude. Therefore, the requirement to stop accurately the rapid hand movement on the target by controlling braking (antagonist) activity can be legitimately termed as a constraint. At this point, we had shown significant contributions of proprioceptive information and of visual signals related to hand and target localisations to the control of reaching movement during its execution. To further understand the crucial role of these feedback loops, we analysed the performance of a proprioceptively deafferented patient in complete darkness, i.e. without vision of the hand and the target. Study 4 demonstrated that reaching movements can be controlled in-flight despite the absence of peripheral sensory feedback loops on hand and target positions during the movement. We thus propose a model of motor control based on the optimal use of feedforward and feedback mechanisms and on the continuity and the rapidity of information processing.
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Contributor : Fabrice Sarlegna <>
Submitted on : Wednesday, April 27, 2005 - 8:18:28 PM
Last modification on : Tuesday, October 20, 2020 - 3:10:25 AM
Long-term archiving on: : Friday, April 2, 2010 - 9:51:15 PM


  • HAL Id : tel-00009128, version 1



Fabrice Sarlegna. CONTROLE EN LIGNE DES MOUVEMENTS D'ATTEINTE MANUELLE DE CIBLE: CONTRIBUTION DES INFORMATIONS DE LOCALISATION DE LA MAIN ET DE LA CIBLE. Neurosciences [q-bio.NC]. Université de la Méditerranée - Aix-Marseille II, 2004. Français. ⟨tel-00009128⟩



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