Neuromechanics Lab, Dept. of Human Movement Sciences,College of Health Sciences, University of Wisconsin-Milwaukee, 1600 E. Hartford Ave, Milwaukee, WI 53201, USA.
J Neurosci Methods. 2011 Jan 30;195(1):10-4. doi: 10.1016/j.jneumeth.2010.10.018. Epub 2010 Nov 11.
We used multi-channel surface electromyograms (EMGs) to examine if electrode location influences coherence measures derived from pairs of EMGs recorded from two hand muscles during a pinch task. A linear probe of 16 electrodes was used to estimate the location of the innervation zone in first dorsal interosseous (FDI) and abductor pollicis brevis (APB). Four electrodes were then placed on the skin overlying each muscle and three bipolar electrode configurations were constructed with their center points directly over the innervation zone, and 15mm distal and proximal to the innervation zone. Ten subjects performed two force-matching tasks for 120s at 2N and 3.5N by pressing a force sensor held between the thumb and index finger. Coherence spectra were calculated from pairs of EMGs recorded from the two muscles. Maximal coherence from 1 to 15Hz and 16 to 32Hz was calculated at both force levels from the EMGs with electrodes centered over the innervation zones of FDI and APB. These values were compared to the maximal coherence from all other EMG comparisons across muscles recorded with electrodes that avoided the innervation zones. ANOVA revealed significant main effects only for electrode location, with a 58.1% increase (p=0.001) in maximal coherence for EMGs detected from pairs of electrodes that avoided the innervation zone (from 0.11±0.02 to 0.18±0.03; mean±95% confidence interval). These results indicate that electrode location relative to the innervation zone influences EMG-EMG coherence and should be carefully considered when placing EMG electrodes on hand muscles.
我们使用多通道表面肌电图（EMG）来检查在捏合任务中记录的来自两个手部肌肉的成对 EMG 时，电极位置是否会影响相干性测量值。使用 16 个电极的线性探头来估计第一背侧骨间肌（FDI）和拇指短展肌（APB）的神经支配区的位置。然后，在皮肤表面放置四个电极，并用三个双极电极配置构建三个电极，其中心点直接位于神经支配区上方，并且距神经支配区 15mm 近端和远端。十个对象通过拇指和食指之间的力传感器进行了 120s 的两次力匹配任务，力分别为 2N 和 3.5N。从两个肌肉记录的成对 EMG 计算相干谱。在两个力水平下，从中心位于 FDI 和 APB 神经支配区的 EMG 计算了 1 到 15Hz 和 16 到 32Hz 的最大相干性。将这些值与通过避开神经支配区的电极记录的所有其他 EMG 比较的最大相干性进行比较。ANOVA 仅显示电极位置的主要影响具有统计学意义，从避开神经支配区的对电极检测到的 EMG 的最大相干性增加了 58.1％（p=0.001）（从 0.11±0.02 增加到 0.18±0.03；平均值±95％置信区间）。这些结果表明，电极相对于神经支配区的位置会影响 EMG-EMG 相干性，在对手部肌肉放置 EMG 电极时应仔细考虑。
