Department of Biomedical Engineering, Pritzker Institute of Biomedical Science and Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA.
IEEE Trans Biomed Eng. 2010 May;57(5):1216-26. doi: 10.1109/TBME.2009.2037493. Epub 2010 Feb 5.
Transcranial magnetic stimulation (TMS) is a noninvasive technique that can alter brain activation by inducing electrical current in neurons using dynamic magnetic fields. Because of its painless nature, clinical usage has expanded to diagnostic purposes and therapeutic treatments. However, several issues and challenges still exist for TMS. A very limited understanding of the interaction between magnetic fields, cortical structure, and consequent brain excitation is currently available. Most previously published models lack key anatomical details that are essential elements in calculating induced electric fields critical to brain activation. In this study, gross human brain and head structures were derived using multiple modality images and a finite-element model was constructed. Furthermore, microstructural detail was incorporated using neocortical columnar structures. Using this detailed model, we investigated the influence of TMS coil position, distance and orientation on induced electric fields, and neocortical activation. Several activation standards and conductivity values were tested for their impact on the distribution of neocortical activation. Optimized activation patterns agreed well with published clinical experiments, under similar coil configurations. A structurally detailed finite-element model capable of accurately predicting neocortical activation for a given coil/magnetic field profile may provide a critical resource for understanding the electrophysiological consequences of TMS and for further refinement of this important technique.
经颅磁刺激（TMS）是一种非侵入性技术，通过利用动态磁场在神经元中产生电流来改变大脑的激活。由于其无痛的性质，临床应用已经扩展到诊断目的和治疗治疗。然而，TMS 仍然存在一些问题和挑战。目前对于磁场、皮质结构和随后的大脑兴奋之间的相互作用的了解非常有限。大多数以前发表的模型都缺乏关键的解剖细节，这些细节是计算对大脑激活至关重要的感应电场的基本要素。在这项研究中，使用多模态图像和有限元模型得出了大体的人脑和头部结构。此外，还使用新皮层柱状结构纳入了微观结构细节。使用这个详细的模型，我们研究了 TMS 线圈位置、距离和方向对感应电场和新皮层激活的影响。测试了几种激活标准和电导率值对新皮层激活分布的影响。优化的激活模式与类似线圈配置下发表的临床实验吻合良好。能够准确预测给定线圈/磁场分布的新皮层激活的结构详细的有限元模型可能为理解 TMS 的电生理后果以及进一步完善这一重要技术提供重要资源。
