Realistic head model: (A) A sagittal cut plane of the T2 weighted MRI showing the different skull layers. (B) The same sagittal cut plane of the manually corrected segmentation including skin, skull compacta, skull spongiosa, neck muscle, eyes and one compartment for inner skull (CSF, GM and WM, before segmentation with Freesurfer). (C) High resolution triangular surface meshes of GM (transparent) and WM (red), constructed with Freesurfer. (D) Sagittal cut plane of the final tetrahedral volume mesh created with TetGen. The different tissue types are represented with different colors.