Resting Functional Connectivity of the Periaqueductal Gray Is Associated With Normal Inhibition and Pathological Facilitation in Conditioned Pain Modulation

These findings indicate that variation in the strength of the PAG resting functional connectivity can explain some of the normal variability in CPM. In addition, pain-facilitative CPM observed in FM patients likely involves attenuation of pain inhibitory as well as amplification of pain facilitative processes in the central nervous system.