Jin Fang, Bruijn Sjoerd M, Daffertshofer Andreas
Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
Faculty of Behavioural and Movement Sciences, Institute Brain and Behavior Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
Front Hum Neurosci. 2022 Jun 24;16:920538. doi: 10.3389/fnhum.2022.920538. eCollection 2022.
The representation of muscles in the cortex can be mapped using navigated transcranial magnetic stimulation. The commonly employed measure to quantify the mapping are the center of gravity or the centroid of the region of excitability as well as its size. Determining these measures typically relies only on stimulation points that yield motor-evoked potentials (MEPs); stimulations that do not elicit an MEP, i.e., non-MEP points, are ignored entirely. In this study, we show how incorporating non-MEP points may affect the estimates of the size and centroid of the excitable area in eight hand and forearm muscles after mono-phasic single-pulse TMS. We performed test-retest assessments in twenty participants and estimated the reliability of centroids and sizes of the corresponding areas using inter-class correlation coefficients. For most muscles, the reliability turned out good. As expected, removing the non-MEP points significantly decreased area sizes and area weights, suggesting that conventional approaches that do not account for non-MEP points are likely to overestimate the regions of excitability.
可以使用导航经颅磁刺激来绘制皮层中肌肉的表征图。用于量化这种映射的常用测量方法是兴奋性区域的重心或质心及其大小。确定这些测量值通常仅依赖于产生运动诱发电位（MEP）的刺激点；那些未引出MEP的刺激，即非MEP点，完全被忽略。在本研究中，我们展示了纳入非MEP点如何影响单相单脉冲经颅磁刺激（TMS）后八块手部和前臂肌肉中可兴奋区域的大小和质心估计。我们对20名参与者进行了重测评估，并使用组内相关系数估计了相应区域质心和大小的可靠性。对于大多数肌肉来说，可靠性结果良好。正如预期的那样，去除非MEP点会显著减小区域大小和区域权重，这表明不考虑非MEP点的传统方法可能会高估兴奋性区域。
