VESTIBULAR INFLUENCES ON ARM MOVEMENTS

描述（由申请人提供）：我们想要研究前庭对手臂伸展运动的影响。最近在人类受试者中发现，向上手臂运动比向下手臂运动的路径曲率更大，加速度持续时间更短，峰值加速度增加。肌肉肌电图活动和计算模型表明，这些运动不对称的产生是因为大脑在向下运动时使用重力作为加速的主要力量，在向上运动时使用重力作为减速的主要力量。在这里，我们提出了一套基本的实验来检查前庭（耳石）信号是否对这些特性具有重要的功能。因此，这个应用程序的目的是双重的。首先，确定猕猴在垂直手臂运动中是否表现出与人类相似的运动学和肌电不对称。其次，研究在手臂运动运动学和肌电图中观察到的上下不对称是否依赖于功能性前庭迷路。我们假设(1)猕猴和人类一样，在进行上下（与水平）手臂运动时表现出运动学和肌电图的不对称性；(2)完整的前庭迷宫在检测重力和规划垂直手臂运动时具有重要的功能。为了实现这些目标，我们将测量手臂运动运动学（Optotrak），以及激动剂和拮抗剂在正常动物和双侧迷路切除术后猴子进行中心向外和中心向内手臂运动时的肌电图活动。为了进一步检查是否有长期适应，我们将在迷路切除术后的前两个月每周检测运动学和肌电图。这些实验将首次在猕猴身上直接研究重力相关的耳石信号在手臂运动的计划和执行中的潜在作用。如果成功，我们将为前庭对手臂运动的影响建立一个坚实的行为背景。未来的神经生理学研究可以探索重力相关的前庭信号如何用于手臂运动的计划和执行。

DESCRIPTION (provided by applicant): We want to pursue a novel line of research regarding vestibular influences upon arm reaching movements. The proposed experiments have been motivated by recent findings in human subjects showing that path curvature is greater, acceleration duration is shorter and peak acceleration is increased for upward versus downward arm movements. Muscle EMG activity and computational modeling have suggested that these kinematic asymmetries are generated because the brain uses gravity as a major force for acceleration during downward movements and for deceleration during upward movements. Here, we propose a basic set of experiments to examine whether vestibular (otolith) signals are functionally important for these properties. Thus, the aims of this application are two-fold. First, to ascertain whether macaques exhibit similar kinematic and EMG asymmetries during vertical arm movements as those observed in humans. Second, to examine whether the observed up/down asymmetries in arm movement kinematics and EMG depend on a functional vestibular labyrinth. We hypothesize (1) that macaques, like humans, show kinematic and EMG asymmetries during execution of up and down (as compared to horizontal) arm movements and (2) that an intact vestibular labyrinth is functionally important for detecting gravity and allowing for cost-effective planning of vertical arm movements. To achieve these goals, we will measure arm movement kinematics (Optotrak), as well as EMG activity from agonists and antagonists as monkeys execute center-out and center-in arm movements both in normal animals and after bilateral labyrinthectomy. To further examine whether there is any long term adaptation, we will be testing kinematics and EMG weekly for the first two months after labyrinthectomy. These experiments will be the first to directly investigate in macaques a potential role of gravity-related otolith signals on the planning and execution of arm movements. If successful, we will establish a solid behavioral context for a vestibular influence upon arm movements. Future neurophysiology studies can then explore how gravity- related vestibular signals are used for arm movement planning and execution.