Conductivity tensors inside the chosen rectangular ROI.

(A) Rectangular ROI marked in the T₂-weighted MR magnitude image. (B) and (C) Mean conductivities reconstructed using tDCS current and two injection currents, respectively. (D) and (E) Conductivity tensor images corresponding to (B) and (C) represented by tri-axial ellipsoids, respectively. The radii of each ellipsoid are proportional to the eigenvalues and their axes are oriented along the directions of the eigenvectors. The colors of the ellipsoid indicate the orientation of the principle eigenvector.