In both magnetic and electrical brain stimulation, anatomical measurements, such as scalp to cortex distance, skull thickness, and CSF density, may correlate to the dosage needed to elicit a Motor Evoked Potential (MEP). This tool allows clinical researchers to measure these parameters at various locations in the brain, so that they may better understand the effect of the dosages they are delivering at various sites.
Philipp (2019). Brain Ruler (https://www.mathworks.com/matlabcentral/fileexchange/61847-brain-ruler), MATLAB Central File Exchange. Retrieved .