Sheffield Cognition and Neuroimaging Laboratory (SCANLab), Academic Clinical Psychiatry, University of Sheffield, The Longley Centre, Sheffield, UK.
Med Biol Eng Comput. 2012 Jul;50(7):671-81. doi: 10.1007/s11517-012-0922-8. Epub 2012 Jun 8.
Computational models have been be used to estimate the electric and magnetic fields induced by transcranial magnetic stimulation (TMS) and can provide valuable insights into the location and spatial distribution of TMS stimulation. However, there has been little translation of these findings into practical TMS research. This study uses the International 10-20 EEG electrode placement system to position a standard figure-of-eight TMS coil over 13 commonly adopted targets. Using a finite element method and an anatomically detailed and realistic head model, this study provides the first pictorial and numerical atlas of TMS-induced electric fields for a range of coil positions. The results highlight the importance of subject-specific gyral folding patterns and of local thickness of subarachnoid cerebrospinal fluid (CSF). Our modelling shows that high electric fields occur primarily on the peaks of those gyri which have only a thin layer of CSF above them. These findings have important implications for inter-individual generalizability of the TMS-induced electric field. We propose that, in order to determine with accuracy the site of stimulation for an individual subject, it is necessary to solve the electric field distribution using subject-specific anatomy obtained from a high-resolution imaging modality such as MRI.
计算模型已被用于估计经颅磁刺激（TMS）产生的电场和磁场，并可以为 TMS 刺激的位置和空间分布提供有价值的见解。然而，这些发现很少被转化为实际的 TMS 研究。本研究使用国际 10-20 脑电图电极放置系统将标准的八字形 TMS 线圈放置在 13 个常用靶点上。本研究使用有限元方法和解剖详细且逼真的头部模型，为一系列线圈位置提供了 TMS 诱导电场的首张图片和数值图谱。结果强调了特定于主体的脑回折叠模式和蛛网膜下腔脑脊液（CSF）局部厚度的重要性。我们的模型表明，高电场主要发生在那些只有一层薄 CSF 覆盖在其上方的脑回的峰上。这些发现对 TMS 诱导电场的个体间可推广性具有重要意义。我们提出，为了准确确定个体刺激部位，有必要使用从高分辨率成像方式（如 MRI）获得的个体特定解剖结构来解决电场分布问题。
