Effects of white matter on EEG of multi-layered spherical head models

Biological tissues are multi-compartmental inhomogeneous media composed of different cellular and subcellular domains. Human head, a multi-compartmental inhomogeneous medium, is composed of scalp, skull, cerebrospinal fluid (CSF), gray matter (GM), white matter (WM), and other subcellular domains. Among these domains, skull and WM show the complicated anisotropy tissue property because of their physiological structure. However, many researchers model human head excluding WM. This research investigates the necessity of WM using four- and five- layered spherical head models. Fourlayered head model excludes WM while five-layered model includes it. The piecewise homogeneous forward model using finite element method is implemented to measure electroencephalogram (EEG) on head surface for both head models. Analyzing these EEGs, this research finds the necessity of using WM to make an accurate human head model.