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Theses

The role of postural adjustments in motor coordination

Abstract : My thesis is that efficient motor coordination relies on the adjustment of the body mechanical properties to the task at hand, by the postural system. I first considered tasks which require immobility, such as standing still and precise and accurate tool manipulation. I developed a generic model of stabilization with neural delays. According to this model, body mechanical properties such as stiffness and inertia play a critical role for maintaining immobility despite external perturbations, since they determine the relative speed at which perturbations will be amplified during the response delay. I then considered the task of initiating movement. The main purpose of postural control is considered to be to counteract the destabilizing force of gravity. However, from the consideration of the mechanical requirements for movement, I arrived at a different interpretation of the experimental findings on stance and movement initiation. I therefore developed the mobility theory, which states that during skilled movement the postural system adjusts the position of the centre of mass (CoM) in view of providing torque for the movement. I then tested to what extent this ability to adjust the CoM position to the task at hand was affected by aging. I performed an experimental analysis of the postural adjustments of elderly fallers and non-fallers. I showed that both elderly fallers and non-fallers are able to adjust their posture to the task, given advance warning, but elderly fallers are less able to rapidly adjust the CoM position during the task. Thus, motor coordination relies on the rapid adjustment of the body mechanical properties to changing task requirements.
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  • HAL Id : tel-02924990, version 1

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Charlotte Le Mouel. The role of postural adjustments in motor coordination. Neurons and Cognition [q-bio.NC]. Sorbonne Université, 2018. English. ⟨NNT : 2018SORUS474⟩. ⟨tel-02924990⟩

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