Neural Control of Grasping

描述（由申请人提供）：人类物体抓取和操纵的动力学和运动学的重要特征已经被表征，为中枢神经系统如何控制手提供了重要的见解。然而，调节多个手部肌肉活动的潜在神经机制尚未得到很好的理解。我们对手部控制的理解存在差距，这对中风等神经损伤后的手部功能康复具有重要的临床意义。在我们之前的工作中，我们主要关注手部肌肉的相关神经输入，以量化抓取物体时力协调的神经基础。我们发现相关神经输入以肌肉对特定的方式分布，即某些肌肉对之间的神经耦合强于其他肌肉对之间的神经耦合。然而，在这种分布中，给定肌肉对的神经耦合强度可以根据任务条件进行调节。然而，这些结果是从相对较少的肌肉和有限的任务条件（握力类型和物体质心）中获得的。本研究的目的是确定手控制的一个关键方面的神经机制：手指力方向的调制。为了实现这一目标，我们将量化(a) EMG振幅和(b)拇指、食指和中指所有肌肉的相关神经输入（相干性）作为手指力方向的函数的调制。我们的工作假设是：(1)当给定肌肉对指尖力方向调制的相对力贡献发生变化时，两块肌肉之间的相干性的力方向依赖性调制将发生；(2)相干性调制将在手部肌肉对之间相关神经输入的不变分布中发生。这些假设将通过一位数力产生任务和多位数抓取任务（分别为目标#1和#2）进行测试。我们的实验结果将确定运动指令控制组的手肌肉是如何调节作为一个功能的力量方向和任务约束。我们的数据有望提高我们对抓取控制的理解，特别是手部肌肉对物体抓取和操作的协同控制的基本机制的基本原理。与公共卫生的相关性：我们相信这些知识将有利于手部功能的康复和恢复，以及神经修复领域。

DESCRIPTION (provided by applicant): Important features of the kinetics and kinematics of human object grasping and manipulation have been characterized, providing significant insight into how the Central Nervous System controls the hand. However, the underlying neural mechanisms that regulate the activity of multiple hand muscles are not yet well understood. This gap in our understanding of hand control has significant clinical implications for rehabilitation of hand function following neurological injury such as stroke. In our previous work we focused on correlated neural input to hand muscles to quantify the neural bases of force coordination during object grasping. We found that correlated neural input is distributed in a muscle-pair specific fashion, i.e., the neural coupling between certain muscle pairs is stronger than that between other muscle pairs. However, within this distribution, the strength of neural coupling of given muscle pairs could be modulated to task conditions. Yet, these results were obtained from a relatively small number of muscles and limited range of task conditions (grip type and object center of mass). The aim of the present study is to determine the neural mechanisms underlying a crucial aspect of hand control: the modulation of digit force direction. To attain this objective we will quantify the modulation of (a) EMG amplitude and (b) correlated neural input (coherence) of all muscles of the thumb, index and middle fingers as a function of digit force direction. Our working hypotheses are that (1) a force-direction dependent modulation of coherence between two muscles will occur as the relative force contribution of a given muscle to the modulation of fingertip force direction changes and (2) coherence modulation will occur within an invariant distribution of correlated neural input among hand muscle pairs. These hypotheses will be tested through one-digit force production tasks and multi-digit grasping tasks (Aim#1 and #2, respectively). The outcomes of our experiments will establish how motor commands controlling groups of hand muscles are modulated as a function of force direction and task constraints. Our data are expected to improve our understanding of the control of prehension, specifically the principles underlying fundamental mechanisms of synergistic control of hand muscles for object grasping and manipulation. Relevance to public health: We believe that this knowledge will be beneficial to rehabilitation and restoration of hand function as well as to the field of neuroprosthetics.