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目的研究脑白质各向异性电导率对头皮电位分布的影响。方法把由扩散张量成像得到的水分子扩散张量采用体积约束规则计算出白质组织的电导率张量,并根据成像的空间信息建立了包括头皮、颅骨、灰质、脑脊液及白质5种组织的真实头的有限元模型。基于此模型,推导了各向异性电导率脑电正问题的一阶有限元数值算法。最后,采用电流偶极子模型计算头皮电位分布。结果脑白质各向异性电导率对头皮电位分布有一定的影响,径切比越大,影响越大;左右分布偶极子比上下分布的影响要大。结论脑电研究中,白质电导率的各向异性为一不可忽略的因素。
Objective To study the effect of white matter anisotropy on scalp potential distribution. Methods The diffusion tensor of water molecules obtained from diffusion tensor imaging was used to calculate the conductivity tensor of white matter using the volume constraint rules. According to the imaging spatial information, five kinds of tissues including scalp, skull, gray matter, cerebrospinal fluid and white matter were established Real head finite element model. Based on this model, the first-order finite element numerical algorithm for the positive EEG problem of anisotropic conductivity is derived. Finally, the current dipole model was used to calculate the scalp potential distribution. Results The white matter anisotropy conductivity had a certain influence on the scalp potential distribution. The larger the diameter-cut ratio, the greater the influence on the scalp potential distribution. The distribution of the left and right dipoles was more affected than the upper and lower distributions. Conclusion EEG anisotropy of white matter is a factor that can not be neglected.