How does the brain coordinate concurrent adaptation of arm movements and standing posture? From previous studies, the postural control system can use information about previously adapted arm movement dynamics to plan appropriate postural control; however, it is unclear whether postural control can be adapted and controlled independently of arm control. The present study addresses that question. Subjects practiced planar reaching movements while standing and grasping the handle of a robotic arm, which generated a force field to create novel perturbations. Subjects were divided into two groups, for which perturbations were introduced in either an abrupt or gradual manner. All subjects adapted to the perturbations while reaching with their dominant (right) arm, then switched to reaching with their non-dominant (left) arm. Previous studies of seated reaching movements showed that abrupt perturbation introduction led to transfer of learning between arms, but gradual introduction did not. Interestingly, in this study neither group showed evidence of transferring adapted control of arm or posture between arms. These results suggest primarily that adapted postural control cannot be transferred independently of arm control in this task paradigm. In other words, whole-body postural movement planning related to a concurrent arm task is dependent on information about arm dynamics. Finally, we found that subjects were able to adapt to the gradual perturbation while experiencing very small errors, suggesting that both error size and consistency play a role in driving motor adaptation.

中文翻译：

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对新动力学的全身适应不会在效应器之间转移

大脑如何协调手臂运动和站立姿势的同时适应？从以前的研究来看，姿势控制系统可以使用有关先前适应的手臂运动动力学的信息来计划适当的姿势控制；然而，尚不清楚姿势控制是否可以独立于手臂控制进行调整和控制。本研究解决了这个问题。受试者在站立并抓住机械臂的手柄时练习平面伸展运动，这会产生一个力场来产生新的扰动。受试者被分成两组，以突然或逐渐的方式引入扰动。所有受试者都适应了扰动，同时用他们的优势（右）臂伸手，然后切换到用他们的非优势（左）臂伸手。先前对坐姿伸展运动的研究表明，突然的扰动引入导致了手臂之间的学习转移，但逐渐引入却没有。有趣的是，在这项研究中，两组均未显示出在手臂之间转移适应性控制或姿势的证据。这些结果主要表明，在该任务范式中，适应的姿势控制不能独立于手臂控制而转移。换句话说，与并发手臂任务相关的全身姿势运动计划取决于手臂动力学信息。最后，我们发现受试者在经历非常小的错误时能够适应逐渐的扰动，这表明错误大小和一致性在驱动运动适应中都起作用。