We used magnetoencephalography (MEG) to investigate the cortical processing of an innocuous facial tactile stimulus in healthy subjects and in a group of subjects suVering from chronic temporomandibular disorder (TMD). Equivalent current dipoles (ECDs) were extracted for a time period of 1 s following stimulus application, and their location, duration and onset time determined. The counts of ECDs extracted did not diVer signiWcantly between the two groups. In contrast, we found statistically signiWcant diVerences in ECD duration and onset time. SpeciWcally, ECD duration was longer in the TMD group in the precentral gyrus, and ECD onset time was earlier in the parietal operculum. In addition, we found diVerences in the internal organization and clustering of the brain areas involved indicating a less tight association and a less coordinated stimulus information processing in the TMD group. Altogether, these results show that an innocuous facial tactile stimulus is diVerently processed in the brain of TMD subjects, when compared to controls, reXecting altered brain mechanisms due to chronic pain.
Bibliographical noteFunding Information:
Acknowledgments We thank Dr. Eric SchiVman and Dr. Donald Nixdorf, Department of Diagnostic and Biological Sciences—TMD and Orofacial Pain Division, for helping selecting the TMD subjects. This work was supported by a Grant-In-Aid Program, Graduate School, University of Minnesota, to I. G. Koutlas, the U. S. Department of Veterans AVairs, and the American Legion Brain Sciences Chair.
Copyright 2013 Elsevier B.V., All rights reserved.
- Equivalent current dipole
- Orofacial pain
- Tactile stimulation
- Temporomandibular disorder