Methods: MEG data were collected from 248 axial gradiometers (4D Neuroimaging) from 10 healthy (30.8±11.1 y) and 8 orofacial pain (37.5±11.6 y) human subjects while 200 tactile stimuli, 50ms in duration each, were applied to the left and right cheek separately with an interstimulus interval of 1-2s. ECDs solutions were derived from artifact-free data using the BESA/Brain Voyager software.
Results: In total, 324 dipoles were localized in 23 cortical areas in both groups. The number of dipoles did not differ significantly between the two groups. However, ECDs duration differed significantly between the 2 groups (longer duration in pain group). In addition, the parietal operculum, the area with most dipoles, ECDs appeared earlier in the pain group than the control group.
Conclusions: The processing of facial tactile information in both groups has similar cortical representation. The longer ECD duration in the pain group suggests persistent cortical activation. In addition, the parietal operculum is enhanced by its earlier activation in the pain group.