FATIGUE OF SEGMENTAL MOTOR MECHANISMS

肌肉疲劳包括一类损害运动的急性影响。 性能。产生疲劳的机制可能涉及到所有因素 从由提供的降速驱动的公式中 超段中枢导致肌肉收缩活性降低 蛋白质。最近，我们实验室提出了四个主题，提供了一个 神经和神经肌肉系统评价的基础 导致疲劳的机制：(1)任务依赖性-- 确定激活各种疲劳机制的条件；(2) 力-疲劳性关系--探索人与人之间的相互作用 力和力之间形成双曲线关系的机制 耐力时间；(3)肌肉智慧--考察 肌肉松弛率和运动神经元放电同时下降 在疲劳期间，这导致了力的最佳化；以及(4)感觉 努力--确定感知努力在精神障碍中的作用 性能。本项目涉及这些主题中的前三个主题，以及 我们的Aim 1的几项技术允许细胞神经生理学 接近努力的感觉。因此，这个项目是必不可少的 基础广泛的四主题方法的组成部分，以理解 肌肉疲劳的神经生物学。 节段性运动机制是一个用来描述整体运动的术语 (系统)脑干/脊髓马达电路、马达单元、 肌肉受体与肌肉、关节和皮肤的节段性作用 传入器。本课题结合节段式电机的疲劳研究。 上述四方办法的机制。目标1解决方案 任务依赖性和肌肉智慧；它涉及量化适应 持续刺激和间歇刺激时运动神经元放电的变化 当脊髓处于被动状态时(即不产生节律性运动 输出)或活动的(即，当产生有节奏的马达输出时)。目标2 解决任务依赖性和力-疲劳性关系，并 研究了中枢神经系统如何利用骨骼类捕获物的特性 肌肉与刺激频率-力的关系减弱和延缓 疲惫。这两组实验都将在被斩首的 海龟，一种特别适合研究的动物物种 脊髓和肌肉之间的关系。 预计这些研究将有助于提供关于 电机控制中尚未解决的基本问题。 此外，这项工作对整形外科、体育运动都有深远的影响 医学上，在各种努力综合征中明显的疲劳性 伴随着更高级的脑功能障碍，脑损伤后的运动恢复， 许多神经肌肉疾病，周围神经肌肉损伤，功能性 电刺激，以及运动假肢的新兴领域。

Muscle fatigue encompasses a class of acute effects which impair motor performance. The mechanisms that produce fatigue may involve all elements of the motor system, from a formulation of the descending drive provided by suprasegmental centers to a reduction in the activity of muscle contractile proteins. Recently our laboratory has proposed four themes that provide a basis for the systematic evaluation of the neural and neuromuscular mechanisms that can contribute to fatigue: (1) task dependency -- to identify the conditions that activate the various fatigue mechanisms; (2) force-fatigability relationship -- to explore the interactions between the mechanisms that result in a hyperbolic relationship between force and endurance time; (3) muscle wisdom -- to examine the association between a concurrent decline in muscle relaxation rate and motor neuron discharge during fatigue that results in an optimization of force; and (4) sense of effort -- to determine the role of perceived effort in the impairment of performance. This project addresses the first three of these themes, and several of our Aim 1 techniques permit a cellular neurophysiological approach to the sense of effort. Thus, this project is an essential component of a broadly based four-theme approach to understanding the neurobiology of muscle fatigue. Segmental motor mechanisms is a term used to describe the integrated (systems) operation of brainstem/spinal motor circuitry, motor units, muscle receptors and the segmental actions of muscle-, joint- and cutaneous afferents. This project links study of the fatigue of segmental motor mechanisms to the quadripartite approach described above. Aim 1 addresses task dependency and muscle wisdom; it involves quantifying the adaptation of motor neuron discharge during sustained and intermittent stimulation when the spinal cord is passive (i.e., not generating a rhythmic motor output) or active (i.e., when generating a rhythmic motor output). Aim 2 addresses task dependency and the force-fatigability relationship and examines how the CNS might exploit the catch-like property of skeletal muscle and the stimulus frequency-force relationship to reduce and delay fatigue. Both sets of experiments will be undertaken on decapitated turtles, an animal species which is particularly well suited for the study of spinal cord-muscle relationships. It is anticipated that these studies will contribute information on fundamental issues in motor control that have not yet been resolved. Furthermore, the work has profound implications for orthopedics, sports medicine, the fatigability that is evident in various effort syndromes that accompany higher brain malfunctions, motor recovery after brain damage, many neuromuscular diseases, peripheral neuromuscular damage, functional electrical stimulation, and the emerging field of motor prosthetics.