Effects of surface EMG rectification on power and coherence analyses: An EEG and MEG study
Effects of surface EMG rectification on power and coherence analyses: An EEG and MEG study
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DOI：
10.1016/j.jneumeth.2006.07.008
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发表时间：
2007-01-30
影响因子：
3
通讯作者：
Liu, Jing Z.
中科院分区：
文献类型：
--
作者：
Yao, Bing;Salenius, Stephen;Liu, Jing Z.
肌电图（EMG）和脑电图（EEG）或脑磁图（MEG）之间的一致性经常被检查，以获得对神经肌肉结合的见解。通常，在计算相干性之前会对EMG信号进行整流。然而，EMG校正在计算EMG-EEG/MEG相干性中的适当性从未被验证。由于整流是一个非线性操作，并改变肌电功率谱，这样的验证是重要的，以确保相干计算的准确性。在这项研究中，我们实验研究了肌电整流对肌电功率谱及其与EEG/MEG信号的相干性的影响。受试者以类似于5-10%最大随意力（在EEG-EMG和MEG-EMG实验中）的持续等长食指外展和以类似于2- 4 Hz的食指轻敲（仅在EEG-EMG实验中）。同时记录来自第一骨间背侧肌（FDI）的双极表面EMG数据和来自对侧初级感觉运动区（C3）的EEG/MEG信号。计算了肌电校正前后的功率谱和与脑电的相干性。结果表明，整流将肌电功率转移到较低的频率，可能会增强运动单元放电的峰值。与EEG/MEG信号的相干性通过EMG整流没有显著改变，表明EMG整流总体上是功率和相干性分析的适当程序。(c)2006 Elsevier B. V.保留所有权利。
Coherence between electromyography (EMG) and electroencephalography (EEG) or magnetoencephalography (MEG) is frequently examined to gain insights on neuromuscular binding. Commonly, EMG signals are rectified before coherence is computed. However, the appropriateness of EMG rectification in computing EMG-EEG/MEG coherence has never been validated. Since rectification is a non-linear operation and alters the EMG power spectrum, such a validation is important to ensure the accuracy of coherence calculation. In this study we experimentally investigated the effects of EMG rectification on EMG power spectra and its coherence with EEG/MEG signals. Subjects performed sustained isometric index finger abduction at similar to 5-10% maximal voluntary force (in both EEG-EMG and MEG-EMG experiments) and index finger tapping at similar to 2-4Hz (in EEG-EMG experiment only). Bipolar surface EMG data from the first dorsal interosseus (FDI) and EEG/MEG signals from the contralateral primary sensorimotor area (C3) were recorded simultaneously. Power spectra and coherence with the EEGIMEG were calculated before and after EMG rectification. The results show that rectification shifts EMG power to lower frequencies, possibly enhancing peaks of motor unit firing. Coherences with the EEG/MEG signals were not significantly changed by EMG rectification, indicating EMG rectification is overall an appropriate procedure in power and coherence analyses. (c) 2006 Elsevier B.V. All rights reserved.