Function of Magnocellular Red Nucleus in Reach-to-grasp

超出提供的空间。这项建议的长期目标是了解触手抓握背后的神经机制。协调的伸手抓握动作对灵长类的运动行为至关重要，高度依赖于小脑对下行运动指令的贡献，而下行运动指令最终将产生适当的肌肉激活模式。了解小脑参与伸手抓握运动，并了解传输到脊髓的控制信号的性质，对于了解神经对运动的控制是至关重要的。建议的研究结果与神经假体、脊髓损伤、中风和运动康复直接相关。目前的研究重点是灵长类动物大细胞红核(RNM)在感觉运动整合中的作用。中间小脑及其对RNM的输出在触觉过程中对手和手指的使用有贡献。大多数前肢RNM神经元在肢体的简单运动中不被激活，但在伸手和抓握的协调动作中同样的神经元被强烈激活。这项提议有两个主要目标。一个目的是正式测试RNM神经元的方向选择性，并帮助解决神经元放电在抽象的、空间的(外部的)或肌肉的(内在的)参照系中编码到达方向的问题。第二个目标是区分不同的内在变量，这些变量可能编码在单个RNM神经元的伸展-抓握相关放电中，即前肢关节的运动学或肢体肌肉活动的动力学。利用运动学数据和肢体肌肉在任务执行过程中的活动同时测量单个单位的放电，将为相关分析提供基础，这些分析将确定单个神经元对控制运动学或肌肉相关参数的贡献的相对强度。行为范式将通过用三种不同的前肢姿势(目标1)引起不同方向的伸手抓住动作(目标1)，或通过伸手以不同距离抓住不同直径的销子(目标2)，或通过以不同速度伸手抓住(目标2)，来分离参数。此外，将通过行为测试、记录肢体肌肉活动以及在任务执行过程中测量失活前后的肢体运动学来分析RNM神经元暂时的、可逆的失活造成的行为缺陷，以确定这些缺陷是否与记录研究得出的结论相匹配。表演网站========================================Section End===========================================

EXCEED THE SPACE PROVIDED. The long-term objective of this proposal is to understand the neural mechanisms underlying reaching to grasp. Coordinated reach-to-grasp movements are of fundamental importance to primate motor behavior and are highly dependent upon cerebellar contributions to the descending motor commands that will ultimately produce the appropriate patterns of muscle activation. Understanding cerebellar participation in reach-to-grasp movements, and understanding the nature of the control signals transmitted to the spinal cord is essential to understanding neural control of movement in general. Results of the proposed studies are directly relevant to neuro-prosthetics, spinal cord injury, stroke, and motor rehabilitation. The focus of the current proposal concerns the functional role of the primate magnocellnlar red nucleus (RNm) in sensorimotor integration. Intermediate cerebellum and its output to RNm contribute to aspects of hand and finger use during reaching. Most forelimb RNm neurons are not activated during simple movements of the limb but the same neurons are strongly activated during the coordinated action of reaching and grasping. This proposal has two major objectives. One objective is to formally test directional selectivity of RNm neurons and to help resolve the issue whether neuronal discharge encodes reach direction in abstract, spatial (extrinsic) or in muscle-based (intrinsic) frames of reference. The second objective is to distinguish between different intrinsic variables that might be encoded in the reach-to-grasp-related discharge of individual RNm neurons, namely kinematics of forelimb joints or dynamics of limb muscle activity. Measuring single-unit discharge simultaneously with kinematic data and activity of limb muscles during task performance will provide a basis for correlational analyses that will determine the relative strength of an individual neuron's contribution to controlling kinematic or muscle-related parameters. The behavioral paradigms will dissociate parameters by eliciting reach-to-grasp movements in different directions with three different forelimb postures (aim 1), or by reaching to grasp different diameter dowels at varying distances (aim 2), or by reaching to grasp at different speeds (aim 2). In addition, behavioral deficits resulting from temporary, reversible inactivation of RNm neurons (aim 3) will be analyzed by behavioral testing, by recording limb muscle activity, and by measuring limb kinematics during task performance pre- and post-inactivation in order to determine if the deficits match the conclusions reached from the recording studies. PERFORMANCE SITE ========================================Section End===========================================