WHOLE HEAD MAPPING OF MAGNETIC-FIELDS FOLLOWING PAINFUL ELECTRIC FINGER SHOCK

Painful intracutaneous electric finger shock was delivered to the fift h digit of the non-dominant hand of five healthy volunteers. Whole hea d evoked magnetic field maps were collected and cortical localizations were calculated using local sphere equivalent current dipole fits. MR I scans were used to identify the anatomical structures where magnetic field sources were located. Anatomically, sources were identified bil aterally in the primary somatosensory region and SII-Insula regions. A dditionally, frontal operculum sources were observed contralaterally i n two subjects. Temporally, an initial contralateral SI activation at 40-60 ms was followed by several SII-Insula responses over the next se veral hundred milliseconds (ms). These SII-Insula responses were often interspersed with additional activations of the SI region. These late r responses were observed in both hemispheres.