CIAMS, Univ. Paris-Sud., Université Paris-Saclay, Orsay, France.
CIAMS, Université d'Orléans, 45067, Orléans, France.
Sci Rep. 2016 Dec 12;6:38845. doi: 10.1038/srep38845.
The study aimed at investigating the extent to which the brain adaptively exploits or compensates interaction torque (IT) during movement control in various velocity and load conditions. Participants performed arm pointing movements toward a horizontal plane without a prescribed reach endpoint at slow, neutral and rapid speeds and with/without load attached to the forearm. Experimental results indicated that IT overall contributed to net torque (NT) to assist the movement, and that such contribution increased with limb inertia and instructed speed and led to hand trajectory variations. We interpreted these results within the (inverse) optimal control framework, assuming that the empirical arm trajectories derive from the minimization of a certain, possibly composite, cost function. Results indicated that mixing kinematic, energetic and dynamic costs was necessary to replicate the participants' adaptive behavior at both kinematic and dynamic levels. Furthermore, the larger contribution of IT to NT was associated with an overall decrease of the kinematic cost contribution and an increase of its dynamic/energetic counterparts. Altogether, these results suggest that the adaptive use of IT might be tightly linked to the optimization of a composite cost which implicitly favors more the kinematic or kinetic aspects of movement depending on load and speed.
本研究旨在探讨在不同速度和负载条件下，大脑在运动控制过程中对交互力矩（IT）的适应程度，以及大脑在运动控制过程中对 IT 的利用或补偿程度。参与者在不规定到达终点的情况下，以较慢、中等和较快的速度，在手臂上施加或不施加负载，进行指向水平平面的手臂运动。实验结果表明，IT 总体上有助于 NT 来协助运动，并且这种贡献随着肢体惯性、指令速度的增加而增加，并导致手部轨迹的变化。我们在（逆）最优控制框架内解释这些结果，假设经验手臂轨迹源自于对特定的、可能是组合的、成本函数的最小化。结果表明，在运动学和动力学层面上，混合运动学、能量和动力学成本对于复制参与者的自适应行为是必要的。此外，IT 对 NT 的较大贡献与运动学成本贡献的总体降低以及其动力学/能量学对应物的增加相关。总的来说，这些结果表明，对 IT 的自适应利用可能与对复合成本的优化密切相关，这种优化隐含地根据负载和速度更倾向于运动的运动学或动力学方面。
