Lu Mai, Ueno Shoogo
Key Lab. of Opt-Electronic Technology and Intelligent Control of Ministry of Education, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu Province, P. R. China.
Department of Applied Quantum Physics, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan.
PLoS One. 2017 Jun 6;12(6):e0178422. doi: 10.1371/journal.pone.0178422. eCollection 2017.
Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS) plays a role in the study of reward and motivation mechanisms, which may be beneficial in the treatment of several neurological and psychiatric disorders. However, electric field distributions induced in the brain by deep transcranial magnetic stimulation (dTMS) are still unknown. In this paper, the double cone coil, H-coil and Halo-circular assembly (HCA) coil which have been proposed for dTMS have been numerically designed. The distributions of magnetic flux density, induced electric field in an anatomically based realistic head model by applying the dTMS coils were numerically calculated by the impedance method. Results were compared with that of standard figure-of-eight (Fo8) coil. Simulation results show that double cone, H- and HCA coils have significantly deep field penetration compared to the conventional Fo8 coil, at the expense of induced higher and wider spread electrical fields in superficial cortical regions. Double cone and HCA coils have better ability to stimulate deep brain subregions compared to that of the H-coil. In the mean time, both double cone and HCA coils increase risk for optical nerve excitation. Our results suggest although the dTMS coils offer new tool with potential for both research and clinical applications for psychiatric and neurological disorders associated with dysfunctions of deep brain regions, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between stimulation depth and focality.
经颅磁刺激（TMS）对更深层脑结构的刺激在奖赏和动机机制研究中发挥着作用，这可能对多种神经和精神疾病的治疗有益。然而，深部经颅磁刺激（dTMS）在大脑中诱发的电场分布仍不清楚。本文对已被提出用于dTMS的双锥线圈、H线圈和光环圆形组件（HCA）线圈进行了数值设计。通过阻抗法数值计算了应用dTMS线圈时在基于解剖学的真实头部模型中的磁通密度分布和感应电场。将结果与标准的八字形（Fo8）线圈的结果进行了比较。模拟结果表明，与传统的Fo8线圈相比，双锥线圈、H线圈和HCA线圈具有显著更深的场穿透深度，但代价是在浅表皮质区域诱发更高且更广泛分布的电场。与H线圈相比，双锥线圈和HCA线圈在刺激深部脑亚区域方面具有更好的能力。同时，双锥线圈和HCA线圈都会增加视神经兴奋的风险。我们的结果表明，尽管dTMS线圈为与深部脑区功能障碍相关的精神和神经疾病的研究及临床应用提供了具有潜力的新工具，但针对特定临床应用选择最合适的线圈设置应基于对刺激深度和聚焦性的平衡评估。
