Department of Neurology and Stroke, University of Tübingen, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.
Brain Topogr. 2024 Jan;37(1):19-36. doi: 10.1007/s10548-023-01018-y. Epub 2023 Nov 23.
Transcranial magnetic stimulation (TMS)-evoked electroencephalography (EEG) potentials (TEPs) provide unique insights into cortical excitability and connectivity. However, confounding EEG signals from auditory and somatosensory co-stimulation complicate TEP interpretation. Our optimized sham procedure established with TMS of primary motor cortex (Gordon in JAMA 245:118708, 2021) differentiates direct cortical EEG responses to TMS from those caused by peripheral sensory inputs. Using this approach, this study aimed to investigate TEPs and their test-retest reliability when targeting regions outside the primary motor cortex, specifically the left angular gyrus, supplementary motor area, and medial prefrontal cortex. We conducted three identical TMS-EEG sessions one week apart involving 24 healthy participants. In each session, we targeted the three areas separately using a figure-of-eight TMS coil for active TMS, while a second coil away from the head produced auditory input for sham TMS. Masking noise and electric scalp stimulation were applied in both conditions to achieve matched EEG responses to peripheral sensory inputs. High test-retest reliability was observed in both conditions. However, reliability declined for the 'cleaned' TEPs, resulting from the subtraction of evoked EEG response to the sham TMS from those to the active, particularly for latencies > 100 ms following the TMS pulse. Significant EEG differences were found between active and sham TMS at latencies < 90 ms for all targeted areas, exhibiting distinct spatiotemporal characteristics specific to each target. In conclusion, our optimized sham procedure effectively reveals EEG responses to direct cortical activation by TMS in brain areas outside primary motor cortex. Moreover, we demonstrate the impact of peripheral sensory inputs on test-retest reliability of TMS-EEG responses.
经颅磁刺激（TMS）诱发的脑电图（EEG）电位（TEPs）提供了皮质兴奋性和连通性的独特见解。然而，听觉和躯体感觉刺激的混杂 EEG 信号使 TEP 的解释变得复杂。我们使用优化的假刺激程序，该程序通过初级运动皮层的 TMS（Gordon 在 JAMA 245:118708, 2021 中建立），区分 TMS 对皮质的直接 EEG 反应与外周感觉输入引起的反应。使用这种方法，本研究旨在研究 TEP 及其在靶向初级运动皮层以外区域（特别是左角回、辅助运动区和内侧前额叶皮质）时的测试-重测可靠性。我们进行了三个完全相同的 TMS-EEG 测试，间隔一周，涉及 24 名健康参与者。在每个测试中，我们使用八字形 TMS 线圈分别针对三个区域进行主动 TMS，而第二个远离头部的线圈则产生听觉输入用于假刺激 TMS。在两种情况下都应用掩蔽噪声和电场刺激，以实现对周围感觉输入的匹配 EEG 反应。在两种情况下均观察到高的测试-重测可靠性。然而，由于从主动 TMS 的 EEG 诱发反应中减去假刺激 TMS 的反应，“清洁”TEP 的可靠性下降，尤其是在 TMS 脉冲后 100ms 以上的潜伏期。对于所有靶向区域，在主动和假刺激 TMS 之间在潜伏期 < 90ms 时发现了明显的 EEG 差异，表现出每个目标特有的独特时空特征。总之，我们优化的假刺激程序有效地揭示了 TMS 在初级运动皮层以外脑区对皮质直接激活的 EEG 反应。此外，我们还证明了外周感觉输入对 TMS-EEG 反应测试-重测可靠性的影响。
