CENTRAL NERVOUS SYSTEM AND MUSCLE FATIGUE

描述（改编自申请人的摘要）： 肌肉疲劳已经被研究了超过世纪。尽管有相当大 获得的知识的外围机制的疲劳，非常 关于大脑，任何生物的控制中心， 神经肌肉操作，调节疲劳肌肉的活动。 因为肌肉疲劳的功能性结果是 产生力量的能力，大脑必须调整其输出，以维持 想要的肌肉力量。当恒定的次最大载荷或力 表面肌电信号（EMG）通常 增大因此，大脑也可能增加其 低强度疲劳过程中的活动。这种可能性并没有 被测试过了当维持最大力时，力和EMG下降 并联大脑活动的水平是否在一个 持续最大自主收缩（MVC）是未知的。也不 清楚来自疲劳肌肉的感觉信息如何影响 皮质运动区的活动。目标1是量化 疲劳时的大脑激活涉及MVC。目标2是确定 低强度疲劳对大脑活动调节的影响。目标3 是确定疲劳的感觉反馈的影响 肌肉对大脑活动的影响大脑激活将由 功能性磁共振成像（fMRI）和运动活动相关 脑电皮层电位（MRCP） 记录（EEG）。初步的fMRI结果显示，（1）尽管 低力（恒定力， 增加EMG）和高力（减少力和EMG）疲劳， 大脑活动的变化惊人地相似：大脑活动 在这两个任务增加;（2）许多高阶皮层领域 在疲劳任务的后期阶段激活增加;以及 (3)对侧的运动皮层的疲劳肌肉“疲劳” 同侧运动皮层的活动显著增加 因为疲劳开始了。假设（1）在两个疲劳任务期间， (MVC和低力），整体大脑激活水平将增加， 但不同皮质野之间的变化不同;（2） 高级运动区和运动皮层同侧的疲劳 在任务的后期，肌肉的活动会增加; 以及（3）在将感觉信息与疲劳阻断之后， 肌肉，对侧运动皮层活动将增加超过 当感觉信息没有被阻挡时。表面肌电和力 与脑图像和MRCP数据同时记录， 受试者执行疲劳任务。这将使校长 研究者检查中枢（脑）和外周（肌肉） 系统同时其目的是，从这些知识中获得 研究将提供有关中枢神经系统的原始数据 在肌肉疲劳时激活。这些知识将有助于我们 了解肌肉疲劳的神经肌肉机制 并且将与神经病学和康复医学相关。

DESCRIPTION (Adapted from the Applicant's Abstract): Muscle fatigue has been studied for over a century. Despite considerable gains in knowledge of the peripheral mechanisms underlying fatigue, very little is known about how the brain, the control center of any neuromuscular operation, modulates the activity of the fatiguing muscle. Because the functional outcome of muscle fatigue is a decline in the ability to generate force, the brain must adjust its output to maintain the desired muscle force. When a constant submaximal load or force is sustained, the surface electromyographic signal (EMG) typically increases. It is possible, therefore, that the brain also increases its activity during a low-force fatigue process. This possibility has not been tested. When a maximal force is sustained the force and EMG decline in parallel. Whether the level of brain activation changes during a sustained maximal voluntary contraction (MVC) is unknown. It is also not clear how the sensory information from the fatiguing muscle influences activities of cortical motor areas. Aim 1 is to quantify the changes in brain activation during fatigue involving MVC. Aim 2 is to determine the effect of low-force fatigue on the adjustment of brain activity. Aim 3 is to determine the effects of sensory feedback from the fatiguing muscles on brain activity. Brain activation will be determined by functional magnetic resonance imaging (fMRI) and motor-activity related cortical potential (MRCP) derived from electroencephalographic recordings (EEG). Preliminary fMRI results showed that (1) despite the differences at the periphery between the low-force (constant force, increasing EMG) and high-force (decreasing force and EMG) fatigue, the change in brain activity was surprisingly similar: brain activity increased during both tasks; (2) many higher-order cortical fields increased in activation during the later stage of the fatigue tasks; and (3) the motor cortex contralateral to the fatiguing muscle "fatigued" and the ipsilateral motor cortex increased its activity substantially as fatigue set in. It is hypothesized that (1) during both fatigue tasks (MVC and low-force), the overall brain activation level will increase, but the changes among different cortical fields will vary; (2) the higher-order motor areas and motor cortex ipsilateral to the fatiguing muscles will increase in activation during the later stage of the tasks; and (3) after blocking the sensory information from the fatiguing muscle, the contralateral motor cortex activity will increase more than when the sensory information is not blocked. Surface EMG and force will be recorded simultaneously with the brain images and MRCP data while subjects perform the fatigue tasks. This will enable the Principal Investigator to examine the central (brain) and peripheral (muscle) systems concurrently. The intent is that knowledge gained from these studies will provide primary data concerning the central nervous system activation during muscle fatigue. This knowledge will contribute to our understanding of the neuromuscular mechanisms underlying muscle fatigue and will have relevance for neurology and rehabilitation medicine.