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的治疗方法，如中风。在这项申请中提出的研究的目标是确定受体水平上的本体感觉--在这种情况下是肌梭--如何导致感知。需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延长的“拮抗性”肌肉中的肌梭，而不是收缩的“激动性”肌肉中的肌梭。具体目标有三个：具体目标1对比激动者和拮抗者肌梭发出的信息，以确定这些群体中的哪一个群体为中枢神经系统提供关于肢体位置和运动的最准确信息。与激动型肌梭不同，我们对拮抗型肌梭对主动关节旋转的反应知之甚少。我们将描述激动者和拮抗者肌梭是如何发出关节位置和运动信号的，以检验中枢神经系统使用这两个种群的输入，但拮抗者肌梭提供的信息是最准确的这一假设。具体目的2是研究拮抗肌梭如何对位置和运动变量进行编码，以告知中枢神经系统肢体在空间中的位置和运动。本实验旨在验证这一假说，即在运动过程中，拮抗性肌梭通过放电模式中的三个不同特征向中枢神经系统发送关于运动中的起始位置、运动速度和肢体位置的信息。具体目标3是表征纺锤马达输入对拮抗性肌梭的影响。过去对激动型肌梭的研究未能解释为什么中枢神经系统在自主运动时会激活纺锤马达系统。本实验旨在验证一种假设，即在精确动作和运动学习过程中，纺锤马达输入提高了拮抗肌梭发出肢体位置和运动信号的精确度，但在负荷运动中，纺锤马达输入不会降低拮抗肌梭发出信号的精确度。

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.