The P22 median nerve SEP component: precentral or postcentral origin? Dipole source analysis from subdural grid recordings

Objective: Since there is general agreement about the origin of the median nerve SEP N20 component, but controversial views about the origin of the following P22 component (precentral versus postcentral), we aimed to localize these components using subdural grid recording. Methods: In four patients undergoing epilepsy surgery with implanted subdural grids over the primary somatosensory cortex, the median nerve was stimulated electrically using standard techniques. EEG-responses were obtained from 64 electrodes, averaged, and fed into the source analysis software (BESA). EEG dipole source analysis of the N20 and…