Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1a, 04103, Leipzig, Germany; Technische Universität Ilmenau, Advanced Electromagnetics Group, Helmholtzplatz 2, 98693, Ilmenau, Germany.
Electrical & Computer Engineering Dept., Worcester Polytechnic Institute, Worcester, MA, 01609, USA.
Brain Stimul. 2022 May-Jun;15(3):654-663. doi: 10.1016/j.brs.2022.04.009. Epub 2022 Apr 18.
When modeling transcranial electrical stimulation (TES) and transcranial magnetic stimulation (TMS) in the brain, the meninges - dura, arachnoid, and pia mater - are often neglected due to high computational costs.
We investigate the impact of the meningeal layers on the cortical electric field in TES and TMS while considering the headreco segmentation as the base model.
We use T1/T2 MRI data from 16 subjects and apply the boundary element fast multipole method with adaptive mesh refinement, which enables us to accurately solve this problem and establish method convergence at reasonable computational cost. We compare electric fields in the presence and absence of various meninges for two brain areas (M1 and DLPFC) and for several distinct TES and TMS setups.
Maximum electric fields in the cortex for focal TES consistently increase by approximately 30% on average when the meninges are present in the CSF volume. Their effect on the maximum field can be emulated by reducing the CSF conductivity from 1.65 S/m to approximately 0.85 S/m. In stark contrast to that, the TMS electric fields in the cortex are only weakly affected by the meningeal layers and slightly (∼6%) decrease on average when the meninges are included.
Our results quantify the influence of the meninges on the cortical TES and TMS electric fields. Both focal TES and TMS results are very consistent. The focal TES results are also in a good agreement with a prior relevant study. The solver and the mesh generator for the meningeal layers (compatible with SimNIBS) are available online.
在对大脑中的经颅电刺激 (TES) 和经颅磁刺激 (TMS) 进行建模时，由于计算成本较高，脑膜（硬脑膜、蛛网膜和软脑膜）通常被忽略。
在考虑头部重建作为基本模型的情况下，我们研究脑膜层对 TES 和 TMS 皮质电场的影响。
我们使用 16 名受试者的 T1/T2 MRI 数据，并应用边界元快速多极方法和自适应网格细化，这使我们能够以合理的计算成本准确地解决这个问题并建立方法收敛性。我们比较了两个脑区（M1 和 DLPFC）和几种不同的 TES 和 TMS 设置下存在和不存在各种脑膜时的电场。
当脑膜存在于 CSF 体积中时，聚焦 TES 的皮质中最大电场平均增加约 30%。通过将 CSF 电导率从 1.65 S/m 降低到约 0.85 S/m，就可以模拟它们对最大电场的影响。与此形成鲜明对比的是，脑膜层对 TMS 皮质电场的影响很弱，当包括脑膜时，平均电场仅略有下降（约 6%）。
我们的结果量化了脑膜对皮质 TES 和 TMS 电场的影响。聚焦 TES 和 TMS 的结果都非常一致。聚焦 TES 的结果也与之前的相关研究非常吻合。脑膜层的求解器和网格生成器（与 SimNIBS 兼容）可在线获得。
