Control of finger movement and force for precision pinch

描述（由申请人提供）：指尖的动态抓握和操纵（“精确捏夹”）取决于协调指尖运动和力的机械能力。产生指尖运动所需的肌肉协调模式与施加指尖力所需的肌肉协调模式不同：指尖运动取决于肌腱偏移，而指尖力依赖于肌腱张力。灵巧的任务如精确捏需要肌肉的协调以满足两个基本要求：（i）从指尖运动到相同方向上的力的过渡（例如，快速拿起铅笔）;以及（i i）指尖运动和不同方向上的力的组合（例如，卷铅笔）。我们将系统地解释食指的肌肉组织是如何协调的，以满足精确捏的这两个基本要求。这一认识将为骨科和神经系统疾病以及衰老中精确捏缩退化的研究提供生物力学基础。 假设一：从指尖运动到沿沿着相同方向的力的顺序过渡涉及以运动和力的精确度为代价在协调模式之间进行插值，插值的精确度取决于允许的误差幅度。 假设二：次最大指尖运动和力在不同方向上的同时产生可以充分约束肌肉相互作用以消除肌肉冗余。 为了验证这些假设，我们提出了一个综合的方法，结合行为研究，机器人分析，生物力学建模和尸体实验。目的1：描述人类用于产生各种食指指尖运动和力量任务的协调模式。肌肉协调模式将被表示为从肌电图（EMG）估计的7维向量。目的2：解释肌肉协调模式如何满足任务的机械要求。食指的生物力学模型将预测再现目标1中观察到的运动和力的协调模式，同时评估肌肉骨骼参数变化的影响，并量化肌肉冗余的程度。目标3：通过驱动尸体手指的肌腱，并将机械输出与自愿和模型动作进行比较，验证EMG和预测的协调模式。

DESCRIPTION (provided by applicant): Dynamic grasp and manipulation with the fingertips ("precision pinch") depend on the mechanical ability to orchestrate fingertip motion and force. The muscle coordination patterns required to produce fingertip motion differ from those associated with exerting fingertip forces: fingertip motion depends on tendon excursions, whereas fingertip force relies on tendon tensions. Dexterous tasks like precision pinch require the coordination of muscles to fulfill two fundamental requirements: (i) the transition from fingertip motion to force in the same direction (e.g., to quickly pick-up a pencil); and (ii) combinations of fingertip motion and force in different directions (e.g., to roll the pencil). We will systematically explain how the musculature of the index finger is coordinated to fulfill these two fundamental requirements of precision pinch. This understanding will provide the biomechanical foundation for much needed studies on the degeneration of precision pinch in orthopedic and neurologic diseases and in aging. HYPOTHESIS I: The sequential transition from fingertip motion to force along the same direction involves interpolating between coordination patterns at the expense of motion and force accuracy, with the abruptness of the interpolation depending on the allowable margin of error. HYPOTHESIS II: The simultaneous production of submaximal fingertip motion and force in different directions can sufficiently constrain muscle interactions to eliminate muscle redundancy. To test these hypotheses, we propose an integrative approach combining behavioral studies, robotics analysis, biomechanical modeling, and cadaveric experiments. AIM 1: To describe the coordination patterns used by humans to produce a variety of index fingertip motion and force tasks. Muscle coordination patterns will be expressed as 7-dimensional vectors estimated from electromyograms (EMG). AIM 2: To explain how the pattern of muscle coordination satisfies the mechanical requirements of the task. A biomechanical model of the index finger will predict coordination patterns that reproduce the motions and forces observed in Aim 1 while evaluating the effects of variability in musculoskeletal parameters, and quantifying the degree of muscle redundancy. AIM 3: To validate the EMG and predicted coordination patterns by actuating the tendons of cadaveric fingers and comparing the mechanical output with the voluntary and model actions.