Intracortical recordings of early pain-related CO2-laser evoked potentials in the human second somatosensory (SII) area

We studied responses of the parieto-frontal opercular cortex to CO2-laser stimulation of Aδ fiber endings, as recorded by intra-cortical electrodes during stereotactic-EEG (SEEG) presurgical assessment of patients with drug-resistant temporal lobe epilepsy. After CO2-laser stimulation of the skin at the dorsum of the hand, we consistently recorded in the upper bank of the sylvian fissure contralateral to stimulation, a negative response at a latency of 135±18 ms (N140), followed by a positivity peaking around 171±22 ms (P170). The stereotactic coordinates in the Talairachʹs atlas of the electrode contacts recording these early responses covered the pre- and post-rolandic part of the upper bank of the sylvian fissure (−27