Spatial and Temporal Control of Targeted Limb Movements

该项目的长期目标是确定人类中枢神经系统（CNS）如何协调自主运动，并最终利用这些信息开发运动障碍（如中风）的治疗方法。本应用中提出的研究目标是确定受体水平上的本体感觉（在这种情况下，是肌肉纺锤体）如何导致感知。要研究的中心假设是，在主动运动中，本体感觉输入的主要来源是伸展“拮抗剂”肌肉中的肌纺锤体，而不是收缩“激动剂”肌肉中的肌纺锤体。具体目的1是对比激动剂和拮抗剂肌肉纺锤体所发出的信息，以确定哪一种群体为中枢神经系统提供了关于肢体位置和运动的最准确的信息。与激动剂肌纺锤体不同，我们对拮抗剂肌纺锤体如何响应主动关节旋转知之甚少。我们将描述激动剂和拮抗剂肌纺锤波是如何传递关节位置和运动信号的，以验证中枢神经系统使用来自两个群体的输入，但拮抗剂肌纺锤波提供的信息是最准确的假设。具体目的2是研究拮抗肌纺锤体如何编码位置和运动变量，告知中枢神经系统肢体在空间中的位置和运动。本实验旨在验证以下假设：在运动过程中，拮抗肌纺锤波通过放电模式中的三个不同特征向中枢神经系统传递有关运动起始位置、运动速度和肢体位置的信息。具体目的3是表征梭状运动输入对拮抗剂肌梭的影响。过去对激动剂肌纺锤波的研究未能解释为什么中枢神经系统在自主运动时激活梭状运动系统。本实验旨在验证以下假设：在精确运动和运动学习过程中，梭形运动输入提高了拮抗肌纺锤波信号在肢体位置和运动中的精度，但在负荷运动中，梭形运动输入不会降低拮抗肌纺锤波信号的精度。

The long-range goal of this project is to determine how the human central nervous system (CNS) coordinates voluntary movement and ultimately to use this information to develop treatments for motor disorders, such as stroke. The goal of the research proposed in this application is to determine how proprioception at the receptor level-in this case, the muscle spindle-leads to perception. The central hypothesis to be investigated is that, in active movement, the primary source of proprioceptive input is muscle spindles in the lengthening, "antagonist" muscles, rather than muscle spindles in the contracting, "agonist" muscles. Three specific aims are addressed: Specific Aim 1 is to contrast the information signaled by agonist and antagonist muscle spindles to determine which of these populations provides the CNS with the most accurate information about limb position and movement. Unlike agonist muscle spindles, little is known about how antagonist muscle spindles respond to active joint rotation. We will characterize how agonist and antagonist muscle spindles signal joint position and movement to test the hypothesis that the CNS uses the input from both populations, but that the information provided by antagonist muscle spindles is the most accurate. Specific Aim 2 is to investigate how antagonist muscle spindles encode position and movement variables, to inform the CNS of the location and movement of the limbs in space. The proposed experiments are designed to test the hypothesis that, during a movement, antagonist muscle spindles signal the CNS information about the starting position, movement velocity, and limb position during movement by three distinctive features within the firing pattern. Specific Aim 3 is to characterize the influence of fusimotor input on antagonist muscle spindles. Past research on agonist muscle spindles has failed to explain why the CNS activates the fusimotor system during voluntary movement. The proposed experiments are designed to test the hypothesis that fusimotor input increases the precision with which antagonist muscle spindles signal limb position and movement during precise movements and during motor learning, but that fusimotor input does not decrease the precision of signaling from antagonist muscle spindles during loaded movements.