Motor evoked potential (MEP), which was elicited by transcranial magnetic stimulation (TMS), has been widely used to detect corticospinal projection from TMS cortical site to trunk muscles. It can help to find the stimulation hotspot in the scalp. However, it fails to precisely describe coordinated activities of trunk muscle groups with only single-channel myoelectric signal. In this study, we aimed to use high-density surface electromyography (sEMG) to explore the effect of cortical TMS on lumbar paravertebral muscles in healthy subjects. The cortical site at 1 cm anterior and 4 cm lateral to vertex was chosen to simulate using a single-pulse TMS with different intensities and forward-bending angles. A high-density electrode array (45 channels) was placed on the surface of lumbar paravertebral muscles to record sEMG signals during a TMS experiment. MEP signals elicited by TMS were extracted from 45-channel recordings and one topographic map of the MEP amplitudes with six spatial features was constructed at each sampling point. The results showed TMS could successfully evoke an oval area with high intensity in the MEP topographic map, while this area mainly located in ipsilateral side of the TMS site. Intensity features related to the high intensity area rose significantly with TMS intensity and forward-bending angle increasing, but location features showed no change. The optimal stimulation parameters were 80% of maximum stimulator output (MSO) for TMS intensity and 30/60 degree for forward-bending angle. This study provided a potentially effective mapping tool to explore the hotspot for transcranial stimulation on trunk muscles.

中文翻译：

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使用高密度表面肌电图绘制腰椎旁肌肉对单脉冲皮质 TMS 的响应


由经颅磁刺激 (TMS) 引发的运动诱发电位 (MEP) 已被广泛用于检测从 TMS 皮质部位到躯干肌肉的皮质脊髓投射。它可以帮助找到头皮的刺激热点。然而，仅用单通道肌电信号无法精确描述躯干肌群的协调活动。在本研究中，我们旨在利用高密度表面肌电图（sEMG）来探讨皮质 TMS 对健康受试者腰椎旁肌肉的影响。选择顶点前方 1 cm、侧方 4 cm 的皮质部位，使用不同强度和前弯角度的单脉冲 TMS 进行模拟。将高密度电极阵列（45 个通道）放置在腰椎旁肌肉表面，以在 TMS 实验过程中记录 sEMG 信号。从 45 通道记录中提取 TMS 引发的 MEP 信号，并在每个采样点构建具有六个空间特征的 MEP 振幅地形图。结果表明，TMS能够在MEP地形图中成功地唤起一个高强度的椭圆形区域，而该区域主要位于TMS部位的同侧。随着TMS强度和前屈角度的增加，与高强度区域相关的强度特征显着增加，但位置特征没有变化。最佳刺激参数为 TMS 强度最大刺激器输出 (MSO) 的 80%，前屈角度为 30/60 度。这项研究为探索躯干肌肉经颅刺激的热点提供了一种潜在有效的绘图工具。