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The influence of biomechanics and visual planning on decision-making of motor actions| old_uid | 11706 |
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| title | The influence of biomechanics and visual planning on decision-making of motor actions |
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| start_date | 2012/10/11 |
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| schedule | 13h30 |
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| online | no |
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| location_info | Ampère |
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| summary | Previous studies have suggested that while planning a movement, humans take into account the biomechanics of the motor apparatus. In particular, there is evidence that the path around an obstacle is typically influenced by the biomechanical properties of the arm in such a way as to minimize the probability of collision. Here I will show the results of some experiments aimed at investigating whether decisions between different reaching movements also take factors of biomechanical anisotropies into account, and whether this takes place prior to movement onset. In particular, we observed how humans make a free choice between two potential trajectories where the options vary in path distance as well as biomechanical factors such as arm inertial load and stiffness anisotropy. Our results show that, given approximately equal kinematic factors, subjects chose movements that optimized aiming precision and stability. Because these decisions had to be made prior to movement onset, they had to be presumably driven by predicted arm biomechanics associated with the potential trajectories. This suggests that we do not make decisions simply on the basis of purely abstract criteria and only take knowledge of biomechanics into account when planning and executing the chosen movement. Instead, we are able to predict the biomechanics of different options and select the one that best optimizes precision and stability. Furthermore, we investigated the influence on subjects’ choices of two factors related to the control of the end-point – difficulty of stopping (DS) and difficulty of aiming (DA) – which are known to influence end-point kinematic errors at the end of straight trajectories. To assess the effect of these additional factors, we had subjects perform a variation of the task in different blocks, with different target widths and with or without the requirement of stopping in the target. The results reveal that the relaxation of the aiming and/or stopping requirements does not reverse the movement preferences expressed during the first set of experiments, but rather exaggerates the influence of biomechanics. This demonstrates that factors of biomechanical anisotropies related to the stopping and aiming factors also play a role in the process of selection between movements. We suggest that parts of the brain involved in predicting the dynamics of movement and in the control of the end-point, putatively including the cerebellum, may contribute to the process of selecting between potential motor actions. |
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| responsibles | Loevenbruck, Welby |
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