School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia.
J Appl Physiol (1985). 2012 Jan;112(2):259-65. doi: 10.1152/japplphysiol.00558.2011. Epub 2011 Nov 3.
Surface electromyography (EMG) responses to noninvasive nerve and brain stimulation are routinely used to provide insight into neural function in humans. However, this could lead to erroneous conclusions if evoked EMG responses contain significant contributions from neighboring muscles (i.e., due to "cross-talk"). We addressed this issue with a simple nerve stimulation method to provide quantitative information regarding the size of EMG cross-talk between muscles of the forearm and hand. Peak to peak amplitude of EMG responses to electrical stimulation of the radial, median, and ulnar nerves (i.e., M-waves) were plotted against stimulation intensity for four wrist muscles and two hand muscles (n = 12). Since electrical stimulation can selectively activate specific groups of muscles, the method can differentiate between evoked EMG arising from target muscles and EMG cross-talk arising from nontarget muscles. Intramuscular EMG responses to nerve stimulation and root mean square EMG produced during maximal voluntary contractions (MVC) of the wrist were recorded for comparison. Cross-talk was present in evoked surface EMG responses recorded from all nontarget wrist (5.05-39.38% Mmax) and hand muscles (1.50-24.25% Mmax) and to a lesser degree in intramuscular EMG signals (∼3.7% Mmax). The degree of cross-talk was comparable for stimulus-evoked responses and voluntary activity recorded during MVC. Since cross-talk can make a considerable contribution to EMG responses in forearm and hand muscles, care is required to avoid misinterpretation of EMG data. The multiple nerve stimulation method described here can be used to quantify the potential contribution of EMG cross-talk in transcranial magnetic stimulation and reflex studies.
表面肌电图（EMG）对非侵入性神经和大脑刺激的反应通常用于深入了解人类的神经功能。然而，如果诱发的 EMG 反应包含来自邻近肌肉的显著贡献（即由于“串扰”），则可能导致错误的结论。我们使用一种简单的神经刺激方法解决了这个问题，该方法提供了关于前臂和手部肌肉之间 EMG 串扰大小的定量信息。对于四个腕部肌肉和两个手部肌肉（n = 12），将 EMG 对桡神经、正中神经和尺神经的电刺激（即 M 波）的峰峰值幅度与刺激强度作图。由于电刺激可以选择性地激活特定的肌肉群，因此该方法可以区分来自目标肌肉的诱发 EMG 和来自非目标肌肉的 EMG 串扰。记录神经刺激的肌内 EMG 反应和最大自主收缩（MVC）期间的均方根 EMG 进行比较。从所有非目标腕部（5.05-39.38% Mmax）和手部肌肉（1.50-24.25% Mmax）记录的诱发表面 EMG 反应中存在串扰，并且在肌内 EMG 信号中程度较小（约 3.7% Mmax）。在 MVC 期间记录的刺激诱发反应和自愿活动中，串扰的程度相当。由于串扰可能对前臂和手部肌肉的 EMG 反应做出相当大的贡献，因此需要小心，以避免对 EMG 数据的误解。这里描述的多神经刺激方法可用于量化 EMG 串扰在经颅磁刺激和反射研究中的潜在贡献。
