The correlation between brain skull thickness asymmetry and the potential on the scalp estimated by two dimensional numerical model of the head

The contribution of skull thickness asymmetry to the Alpha amplitude asymmetry was investigated by a two dimensional computerized model. The model consists of three conductive layers representing the skull, the scalp, and the cortex with radially oriented dipole and with left right asymmetry of the skull thickness. The potential created by the dipole was calculated using Laplace´s equation with boundary conditions, while allowing a quasistatic formulation and a linear media. The electric potential on the surface of the volume conductor is calculated by numerical differentiation using iterative successive over relaxation method for solving the large set of the resulting linear algebraic equations. It was found that for realistic values of maximal skull thickness asymmetry the potential asymmetry is approximately 10%.