Task-dependent modulation of 15-30 Hz coherence between rectified EMGs from human hand and forearm muscles
Task-dependent modulation of 15-30 Hz coherence between rectified EMGs from human hand and forearm muscles
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DOI：
10.1111/j.1469-7793.1999.0559v.x
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发表时间：
1999-04-15
影响因子：
5.5
通讯作者：
Lemon, RN
中科院分区：
文献类型：
--
作者：
Kilner, JM;Baker, SN;Lemon, RN
1.最近的报告表明，在熟练的手部运动过程中，人类受试者和猴子的感觉运动皮层中15-30 Hz范围内的振荡活动中与任务相关的变化。在猴子身上，这些振荡已经被证明与手和前臂肌肉的肌电图活动中的振荡活动是一致的。在这项研究中，我们研究了人类志愿者在需要精确抓握两个弹簧加载杠杆的任务中肌电图（EMG）振荡的调制。研究了两个任务：在“保持”任务中，要求受试者保持稳定的握力（约2.1 N或2.6 N）8 s。在“斜坡”任务中，有一个初始的保持时间为3秒（力约2 1 N），然后在2秒的时间内，握力线性增加。任务结束时，在更高的力水平（约2.6 N）下进一步稳定保持3 s。记录了12名受试者的5块手和前臂肌肉的表面肌电图。计算每对肌肉之间振荡活动的相干性。分析了1到100 Hz之间的频率。在保持任务期间，每个受试者在15-30 Hz带宽的相干谱中显示出峰值。在杠杆的初始运动期间，这种一致性是不存在的。在斜坡任务期间，在15-30 Hz范围内的相干性在运动阶段期间也显著降低，并且在第二保持期间相对于初始保持显著增加。有一致性之间的同时记录脑磁图（MEG）和肌电图在稳定的抓持任务，这种一致性消失在最初的杠杆运动。使用一个单一的等效电流偶极子源模型，相干皮层活动被定位到对侧运动皮层的手部区域。这表明，肌电-肌电相干性，因此，至少部分，皮层起源。结果进行了讨论，在一个可能的作用，在保持抓地力的运动单位的有效招聘同步。
1. Recent reports have shown task-related changes in oscillatory activity in the 15-30 Hz range in the sensorimotor cortex of human subjects and monkeys during skilled hand movements. In the monkey these oscillations have been shown to be coherent with oscillatory activity in the electromyographic activity of hand and forearm muscles.2. In this study we investigated the modulation of oscillations in the electromyogram (EMG) of human volunteers during tasks requiring precision grip of two spring-loaded levers.3. Two tasks were investigated: in the 'hold' task, subjects were required to maintain a steady grip force (ca 2.1 N or 2.6 N) for 8 s. In the 'ramp' task, there was an initial hold period for 3 s (force ca 2 1 N) followed by a linear increase in grip force over a 2 s period. The task ended with a further steady hold for 3 s at the higher force level (ca 2.6 N).4. Surface EMGs were recorded from five hand and forearm muscles in 12 subjects. The coherence of oscillatory activity was calculated between each muscle pair. Frequencies between 1 and 100 Hz were analysed.5. Each subject showed a peak in the coherence spectra in the 15-30 Hz bandwidth during the hold task. This coherence was absent during the initial movement of the levers. During the ramp task the coherence in the 15-30 Hz range was also significantly reduced during the movement phase, and significantly increased during the second hold period, relative to the initial hold.6. There was coherence between the simultaneously recorded magnetoencephalogram (MEG) and EMG during steady grip in the hold task; this coherence disappeared during the initial lever movement. Using a single equivalent current dipole source model, the coherent cortical activity was localized to the hand region of the contralateral motor cortex. This suggests that the EMG-EMG coherence was, therefore, at least in part, of cortical origin.7. The results are discussed in terms of a possible role for synchrony in the efficient recruitment of motor units during maintained grip.