Equivalent source estimation based on the calculation of the electric field from depth EEG data

A method for the estimation of equivalent source position and strength based on the estimation of the electric field from depth electroencephalographic (EEG) data is described. The calculation method for the electric field is based on a tetrahedral geometry. The proposed approach for source parametrization is twofold. Firstly, the distribution of electrical energy by the squared norm of the electric field vector can give an estimate of the source position, without having to assume a dipole source. Secondly, the average electric field can be related to the dipole magnitude and orientation of the equivalent source. Simulation results demonstrated the potential usefulness of the method. The effects of noise and sampling, and the geometry of the measurement system (i.e. implanted electrodes) relative to the source were also investigated through simulations.