Neural Control of Grasping

神经和肌肉骨骼疾病严重损害手指运动和力量的复杂协调，这是我们掌握和操纵物体的能力的特征。了解抓握的生理控制机制对于理解影响手功能的病理是必不可少的。本提案的长期目标是表征负责控制抓取运动的正常肌肉激活模式，特别是神经系统用于协调手部大量肌肉的策略。这一目标将通过研究多个手部肌肉的同时激活和握力的协调来实现。目前的建议有三个具体目标：将手部肌肉活动的组织描述为手和手腕姿势的功能（目标1）；以确定运动单元同步是否依赖于任务约束（物体的大小和质心位置；目标2）和握持类型（力量与精确握持，以及物体形状；目标3）。提出的研究是基于先前工作支持的假设，即多个握力的协调是基于协同作用，减少了必须独立控制的自由度。我们将确定多个手部肌肉的活动如何作为手指/手腕姿势和任务约束的功能进行协调。手部肌肉活动将通过肌内肌电图记录(a)干扰多单元肌电图和(b)单个运动单元活动来测量。每个手指施加的接触力将通过力传感器以三维方式测量。本基础研究考察的问题与手部功能的康复和恢复有关。

Neurological and musculo-skeletal diseases severely impair the complex coordination of finger motion and forces that characterizes our ability to grasp and manipulate objects. Knowledge of the physiological control mechanisms of prehension is essential for an understanding of the pathologies that affect hand function. The long-term objective of the present proposal is to characterize the normal patterns of muscle activation responsible for the control of grasping movements, in particular the strategies used by the nervous system to coordinate the large number of muscles of the hand. This objective will be pursued by studying the simultaneous activation of multiple hand muscles and the coordination of grip forces. The present proposal has three specific aims: to characterize the organization of hand muscle activity as a function of hand and wrist posture (Aim number 1); to determine whether motor unit synchronization is dependent on task constraints (object's size and center of mass location; Aim number 2) and grip type (power vs. precision grip, and object shape; Aim number 3). The proposed studies are based on the hypothesis, supported by previous work, that the coordination of multiple grip forces is based on synergies reducing the number of degrees of freedom that has to be controlled independently. We will determine how the activity of multiple hand muscles is coordinated as a function of finger/wrist posture and task constraints. Hand muscle activity will be measured by intramuscular electromyographic recording as (a) interference multi-unit EMG and (b) single motor unit activity. Contact forces exerted by each finger will be measured in three dimensions by force sensors. The issues examined by this basic research are relevant to efforts in rehabilitation and restoration of hand function.