Distinct adaptation processes underlie multidigit force coordination for dexterous manipulation
Distinct adaptation processes underlie multidigit force coordination for dexterous manipulation
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DOI：
10.1152/jn.00329.2022
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发表时间：
2023-02-01
影响因子：
2.5
通讯作者：
Fu，Qiushi
中科院分区：
文献类型：
--
作者：
Smith，Michael D.;Hooks，Kevin;Fu，Qiushi
人类感觉运动系统可以通过更新运动命令来适应环境动态的各种变化，以提高重复接触相同任务后的性能。然而，对于灵巧操作来说，适应过程的特征和机制仍然未知，这是一种独特的运动任务，在这一任务中，身体通过多个效应器(即数字)与环境进行物理交互。我们通过使用机器人机械手来研究三脚架握持的物体在机械扰动后指力协调的变化，从而解决了这一问题。随着参与者逐渐适应在扰动下举起物体，我们对指力协调的两个组成部分进行了量化。一个是直接抵消摄动的特定方向操纵力矩，另一个是支持抓取稳定性和刚性的与方向无关的内力矩。我们发现，任务绩效的尝试到尝试的提高与操纵力矩的增加和内部力矩的逐渐减少有关。这两个时刻具有不同的适应速度。我们还研究了这两个力协调分量如何响应扰动方向的变化。重要的是，我们发现操纵力矩对重复暴露于具有相反扰动方向的先前背景的程度很敏感，而内部力矩则不敏感。然而，内力矩对是否经历过变化后的扰动方向很敏感。我们的结果首次揭示了多指力协调适应灵巧操作的两个不同的过程。NEW&NOTEWORTHY用一种新的实验设计量化了多指物体操作中指力协调的变化，在该实验设计中，人类参与者适应了施加在对象上的机械扰动。我们的结果表明，指力协调的适应性可以由两个不同的成分来表征，它们运行在不同的时间尺度上。我们进一步证明，这两个分量对微扰方向的变化的响应是不同的。
The human sensorimotor system can adapt to various changes in the environmental dynamics by updating motor commands to improve performance after repeated exposure to the same task. However, the characteristics and mechanisms of the adaptation process remain unknown for dexterous manipulation, a unique motor task in which the body physically interacts with the environment with multiple effectors, i.e., digits, in parallel. We addressed this gap by using robotic manipulanda to investigate the changes in the digit force coordination following mechanical perturbation of an object held by tripod grasps. As the participants gradually adapted to lifting the object under perturbations, we quantified two components of digit force coordination. One is the direction-specific manipulation moment that directly counteracts the perturbation, whereas the other one is the direction-independent internal moment that supports the stability and stiffness of the grasp. We found that trial-to-trial improvement of task performance was associated with increased manipulation moment and a gradual decrease of the internal moment. These two moments were characterized by different rates of adaptation. We also examined how these two force coordination components respond to changes in perturbation directions. Importantly, we found that the manipulation moment was sensitive to the extent of repetitive exposure to the previous context that has an opposite perturbation direction, whereas the internal moment did not. However, the internal moment was sensitive to whether the postchange perturbation direction was previously experienced. Our results reveal, for the first time, that two distinct processes underlie the adaptation of multidigit force coordination for dexterous manipulation.NEW & NOTEWORTHYChanges in digit force coordination in multidigit object manipulation were quantified with a novel experimental design in which human participants adapted to mechanical perturbations applied to the object. Our results show that the adaptation of digit force coordination can be characterized by two distinct components that operate at different timescales. We further show that these two components respond to changes in perturbation direction differently.