Neural Control of Grasping

描述(申请人提供)：描述了人类抓取和操纵物体的动力学和运动学的重要特征，为了解中枢神经系统如何控制手提供了重要的洞察力。然而，调节手部多块肌肉活动的潜在神经机制还没有被很好地理解。我们对手控制的理解上的这种差距对中风等神经损伤后手功能的康复具有重要的临床意义。在我们以前的工作中，我们将重点放在手部肌肉的相关神经输入上，以量化物体抓取过程中力协调的神经基础。我们发现，相关的神经输入是以肌肉对特有的方式分布的，即某些肌肉对之间的神经耦合比其他肌肉对之间的耦合更强。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，这些结果是在相对较少的肌肉和有限的任务条件(握力类型和物体重心)下获得的。本研究的目的是确定手控制的一个关键方面的神经机制：指力方向的调节。为了实现这一目标，我们将量化拇指、食指和中指所有肌肉的(A)肌电幅度和(B)相关神经输入(连贯性)的调制作为指力方向的函数。我们的工作假设是(1)随着给定肌肉对指尖力方向调制的相对力贡献的改变，两个肌肉之间的一致性将发生与力方向相关的调制，以及(2)一致性调制将发生在手部肌肉对之间相关神经输入的不变分布内。这些假设将通过一位数的力量生产任务和多位数的抓取任务(分别为目标1和目标2)进行检验。我们的实验结果将确定运动指令如何控制手部肌肉群，作为力量方向和任务限制的函数。我们的数据有望提高我们对抓取控制的理解，特别是手部肌肉协同控制物体抓取和操纵的基本机制背后的原理。与公众健康相关：我们相信，这些知识将有益于手功能的康复和恢复，以及神经假体领域。

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.