Department of Clinical Neurophysiology, MIRA Institute for Technical Medicine and Biomedical Technology, University of Twente, 7500 KA Enschede, The Netherlands.
IEEE Trans Neural Syst Rehabil Eng. 2013 May;21(3):376-82. doi: 10.1109/TNSRE.2012.2228674. Epub 2013 Jan 23.
Co-registration of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) is a new, promising method for assessing cortical excitability and connectivity. Using this technique, a TMS evoked potential (TEP) can be induced and registered with the EEG. However, the TEP contains an early, short lasting artifact due to the magnetic pulse, and a second artifact, which depends on the location of stimulation and can last up to 40 ms. Different causes for this second artifact have been suggested in literature. In this study, we used principal component analysis (PCA) to suppress both the first and second artifact in TMS-EEG data. Single pulse TMS was applied at the motor and visual cortex in 18 healthy subjects. PCA using singular value decomposition was applied on single trials to suppress the artifactual components. A large artifact suppression was realized after the removal of the first five PCA components, thereby revealing early TEP peaks, with only a small suppression of later TEP components. The spatial distribution of the second artifact suggests that it is caused by electrode movement due to activation of the temporal musculature. In conclusion, we showed that PCA can be used to reduce TMS-induced artifacts in EEG, thereby revealing components of the TMS evoked potential.
经颅磁刺激（TMS）与脑电图（EEG）的同机注册是评估皮质兴奋性和连通性的一种新的、很有前途的方法。使用该技术，可以诱发 TMS 诱发电位（TEP）并与 EEG 一起记录。然而，TEP 包含由于磁场脉冲引起的早期、短暂的伪影，以及第二个依赖于刺激位置且可持续长达 40ms 的伪影。文献中提出了这种第二种伪影的不同原因。在这项研究中，我们使用主成分分析（PCA）来抑制 TMS-EEG 数据中的第一种和第二种伪影。在 18 名健康受试者的运动和视觉皮层上施加单脉冲 TMS。在单试次上使用奇异值分解进行 PCA，以抑制人为成分。去除前五个 PCA 分量后，可以实现大的伪影抑制，从而揭示早期 TEP 峰值，而仅对后期 TEP 分量进行较小的抑制。第二个伪影的空间分布表明它是由于颞肌激活引起的电极运动引起的。总之，我们表明 PCA 可用于减少 EEG 中的 TMS 诱发的伪影，从而揭示 TMS 诱发电位的成分。
