Rectification of EMG in low force contractions improves detection of motor unit coherence in the beta-frequency band
Rectification of EMG in low force contractions improves detection of motor unit coherence in the beta-frequency band
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DOI：
10.1152/jn.00296.2013
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发表时间：
2013-10-01
影响因子：
2.5
通讯作者：
Halliday, David M.
中科院分区：
文献类型：
--
作者：
Ward, Nicholas J.;Farmer, Simon F.;Halliday, David M.
在频谱分析之前对表面肌电图进行校正是用于检测运动单位放电模式的一种行之有效的预处理方法。最近的一些研究对在光谱分析之前进行校正的必要性提出了质疑，指出没有支持的实验证据来证明校正的合理性。我们提出了一个分析的190个记录，从13个科目组成的同时记录的配对单运动单位和表面肌电从伸趾长肌在中指伸展对重力（卸载条件）和对重力加惯性负荷（加载条件）。我们直接检查的假设，整流表面肌电图是一个更好的预测的频率分量的运动单位同步比未整流（或原始）的EMG在β频段（15-32赫兹）。我们使用多变量分析和估计的部分相干性配对的单个单位使用整流和未整流的表面肌电图作为预测。我们使用残差偏相关测量来量化原始和整流EMG之间的差异作为预测因子，并分别分析空载和负载条件。空载条件下的剩余相关性为22%与原始EMG和3.5%与整流EMG，负载条件下的剩余相关性为5.2%与原始EMG和1.4%与整流EMG。我们解释这些结果作为强有力的支持实验证据，有利于使用表面肌电校正前的预处理步骤，频谱分析。
Rectification of surface EMG before spectral analysis is a well-established preprocessing method used in the detection of motor unit firing patterns. A number of recent studies have called into question the need for rectification before spectral analysis, pointing out that there is no supporting experimental evidence to justify rectification. We present an analysis of 190 records from 13 subjects consisting of simultaneous recordings of paired single motor units and surface EMG from the extensor digitorum longus muscle during middle finger extension against gravity (unloaded condition) and against gravity plus inertial loading (loaded condition). We directly examine the hypothesis that rectified surface EMG is a better predictor of the frequency components of motor unit synchronization than the unrectified (or raw) EMG in the beta-frequency band (15-32 Hz). We use multivariate analysis and estimate the partial coherence between the paired single units using both rectified and unrectified surface EMG as a predictor. We use a residual partial correlation measure to quantify the difference between raw and rectified EMG as predictor and analyze unloaded and loaded conditions separately. The residual correlation for the unloaded condition is 22% with raw EMG and 3.5% with rectified EMG and for the loaded condition it is 5.2% with raw EMG and 1.4% with rectified EMG. We interpret these results as strong supporting experimental evidence in favor of using the preprocessing step of surface EMG rectification before spectral analysis.