CENTRAL NERVOUS SYSTEM AND MUSCLE FATIGUE

描述（改编自申请人的摘要）： 肌肉疲劳的研究已经有一个多世纪了。尽管相当 获得关于疲劳的外围机制的知识，非常重要 我们对大脑（任何事物的控制中心）如何运作知之甚少。 神经肌肉操作，调节疲劳肌肉的活动。 因为肌肉疲劳的功能结果是肌力下降 产生力量的能力，大脑必须调整其输出以维持 所需的肌肉力量。当恒定的次最大负载或力 持续的，表面肌电信号（EMG）通常 增加。因此，大脑也有可能增加其 低力疲劳过程中的活动。这种可能性还没有 经测试。当维持最大力量时，力量和肌电图下降 并行。大脑激活水平在一段时间内是否发生变化 持续最大自主收缩（MVC）尚不清楚。也不是 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 是量化变化 疲劳期间涉及 MVC 的大脑激活。目标 2 是确定 低力疲劳对大脑活动调节的影响。目标 3 是确定疲劳感觉反馈的影响 肌肉对大脑活动的影响。大脑激活将由以下因素决定 功能磁共振成像（fMRI）和运动活动相关 来自脑电图的皮质电位 (MRCP) 录音（脑电图）。初步的功能磁共振成像结果表明（1）尽管 低力（恒定力， 增加肌电图）和高力（减少力和肌电图）疲劳， 大脑活动的变化惊人地相似：大脑活动 在这两项任务期间增加； (2)许多高阶皮质区 疲劳任务后期激活度增加；和 (3)疲劳肌肉对侧的运动皮层“疲劳” 并且同侧运动皮层的活动大大增加 当疲劳开始时。假设 (1) 在两项疲劳任务期间 （MVC和低力），整体大脑激活水平会增加， 但不同皮质区之间的变化会有所不同； （2） 疲劳同侧的高阶运动区和运动皮层 在任务的后期阶段，肌肉的激活度会增加； (3) 阻断疲劳的感觉信息后 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。表面肌电图和力将 与脑部图像和 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（大脑）和外周（肌肉） 系统同时进行。目的是从这些内容中获得知识 研究将提供有关中枢神经系统的主要数据 肌肉疲劳时激活。这些知识将有助于我们 了解肌肉疲劳背后的神经肌肉机制 并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.