Anatomical localization and intra-subject reproducibility of laser evoked potential source in cingulate cortex, using a realistic head model

Objectives: To (i) accurately localize the cingulate source of late laser evoked potentials (LEPs) using a realistic head model incorporating the individualʹs anatomy and (ii) assess the within-subject reproducibility of this source. Methods: Late LEPs, elicited by painful CO2 laser stimulation of the right forearm, were recorded from 62 electrodes in one healthy subject. This was repeated 9 times, over 3 different days. Dipole source localization (CURRY 4.0) was performed on the most prominent (P2) peak of each LEP data set, using a head model derived from the subjectʹs structural magnetic resonance image. Results: In all cases the P2 LEP peak was best explained by a dipole located close to the border of the caudal division of left anterior cingulate cortex with left posterior cingulate cortex (mean residual variance was 1.7±0.4%). The maximum standard deviation from the mean dipole location was 3.2 mm. Conclusions: This study demonstrates that the location of the cingulate source of late LEPs is highly reproducible within this subject, when analyzed in this way, and suggests involvement of caudal cingulate regions in pain processing