Conditioned Pain Modulation
The phenomenon currently known as “conditioned pain modulation” (CPM), “diffuse noxious inhibitory controls” (DNIC), “descending control of nociception” (DCN), or simply “counterirritation” relies on the observation that pain in one part of the body inhibits pain in another part. This phenomenon has been shown electrophysiologically, and behaviourally in both rodents and humans. MOGILab recently documented that, in both mice and rats, this is only true when the “test” stimulus (i.e., the noxious stimulus being measured before and during/after application of the “conditioning” stimulus) is of high intensity. When using (currently far more common) lower-intensity test stimuli, instead of analgesia we see robust hyperalgesia. Current efforts are aimed at determining the neurochemistry underlying this “anti-CPM”, and to see whether it can be shown in humans as well.