“…The Poisson equation, which describes the electric fields of the brain within volume-conductor theory, is solved for each layer separately, and the mathematical solutions are matched at the layer interfaces to obtain an analytical expression for the EEG signal as set up by a current dipole in the brain tissue. This model has been extensively used in analysis of EEG signals, see, e.g., Peraza et al (2012); Wong et al (2008); Chu et al (2012), but it is also useful for validation of general numerical schemes, such as the Finite Element Method (FEM) (Larson and Bengzon, 2013). The FEM approach is not limited by specific assumptions on head symmetry and can, in principle, take into account an arbitrarily complex spatial distribution of electrical conductivity representing the electrical properties of the head (Bangera et al, 2010; Huang et al, 2016).…”