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的历史了。尽管有相当大的 对疲劳潜在的外周机制的知识的增加，非常 很少有人知道大脑是如何控制任何生物的 神经肌肉手术，调节疲劳肌肉的活动。 因为肌肉疲劳的功能结果是 产生力量的能力，大脑必须调整其输出以保持 理想的肌肉力量。当恒定的次最大载荷或力 持续的，表面肌电信号(EMG)通常 增加。因此，大脑也有可能增加它的 在低力疲劳过程中的活动。这种可能性并没有 已经测试过了。当承受最大力时，力和肌电都会下降 并行的。大脑的激活水平是否会在 持续性最大自主收缩(MVC)尚不清楚。它也不是 弄清楚疲劳肌肉的感觉信息是如何影响 皮质运动区的活动。目标1是将以下变化量化 疲劳时大脑激活，涉及MVC。目标2是确定 低力疲劳对脑活动调节的影响。目标3 是为了确定疲劳对感觉反馈的影响 肌肉对大脑活动的影响。大脑的激活将由以下因素决定 功能磁共振成像(FMRI)与运动相关 基于脑电的皮层电位(MRCP) 记录(EEG)。初步的fMRI结果显示：(1)尽管 在外围低力(恒定力， 增加肌电)和高力(减力和肌电)疲劳， 大脑活动的变化惊人地相似：大脑活动 在这两个任务中都增加了；(2)许多更高阶的皮层区域 在疲劳任务的后期阶段激活增加；以及 (3)疲劳肌肉对侧的运动皮质“疲劳” 同侧运动皮质的活动显著增加。 随着疲惫的到来。假设(1)在两个疲劳任务期间 (MVC和低力)，总体大脑激活水平将增加， 但不同皮质区域之间的变化会有所不同；(2) 疲劳同侧的高级运动区和运动皮质 在任务的后期，肌肉的活跃度会增加； (3)阻断疲劳后的感觉信息 肌肉，对侧运动皮质活动会增加超过 当感觉信息没有被阻挡时。表面肌电信号和作用力 与脑部图像和MRCP数据同步记录，同时 受试者执行疲劳任务。这将使主体 检查中枢(脑)和外周(肌肉)的调查员 系统同时运行。其意图是，从这些方面获得的知识 研究将提供有关中枢神经系统的基本数据 肌肉疲劳时的激活。这一知识将有助于我们的 了解肌肉疲劳的神经肌肉机制 并将对神经病学和康复医学具有重要意义。

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.