Regarding Extraction of Electric Field in Nerve Regions

[gotou]

I would like to extract the magnitude of the electric field only in the nerve region when a voltage is applied to the arm, based on the manual section 3.6.3 “Yoon-Sun Arm Stimulation,” using MATLAB. How should I approach this?

Also, when I try to visualize the electric field only in the nerve region using a mask filter (setting everything except Nerve_〇〇 to 0), the result appears discontinuous, as shown in the attached image. For the grid, I have set the maximum step and geometry resolution to 0.5 mm for all directions.