Combined source simulation method - fictitious medium method for solving anisotropic EEG problems

An electroencephalography (EEG) problem in bio-electromagnetics is to estimate dipolar current sources inside the brain from the measured electric potential distribution on the scalp surface. Traditional linear algorithms are the low-resolution electromagnetic tomography algorithms (LORETA) including improved ones. It is easy to solve isotropic EEG problems by means of them. But the skull conductivity is anisotropic obviously. In this paper, proposed is a source simulation method combined with the fictitious medium method for solving the anisotropic skull layer problem to obtain the electric potential and field intensity on the cortex. Then it can be connected with LORETA. A good agreement between the numerical result and analytical result of the 4-layer spherical head model has been observed. It is shown that this method is effective and feasible. Its prominent advantages are simple and timesaving. And this numerical computation method is suitable for not only spherical head models but also realistic head models with the thin anisotropic layer.