交变磁场在皮层内产生感应电场的理论计算

THEORETICAL CALCULATION OF THE ELECTRIC FIELD INDUCED IN THE CORTEX BY ALTERNATING MAGNETIC FIELD

作为大脑皮层磁刺激基础性研究工作的一部分，本文在建立头部球形模型的基础上，考虑了边界条件的影响，对任意形状的线圈在头内产生的感应电场进行了理论推导，得出了球坐标系中的数值计算表达式，并由此给出了环形及八字形线圈感应电场分布的具体计算结果。

 Mathematical method was reported for calculating electric field induced in the cortex during magnetic stimulation. The electric field arose from 2 sources: (1) the alternating magnetic field created an electric field in the tissue by electromagnetic induction, and (2) a charge accumulation arose on the surface of the head and produced its own eletrostatic field. A singlesphere model was used to represent the brain. The electric field as a function of the coil size, position and shape was computed numerically. Different coil shapes such as circle and figureof eight were considered, and distributions of the induced electric fields were given.