Conditioned Pain Modulation Using Painful Cutaneous Electrical Stimulation or Simply Habituation?

Painful cutaneous electrical stimulation (PCES) and corresponding evoked potentials led to a significant pain relief and decrease of evoked potentials and has been used to analyze conditioned pain modulation (CPM). However, it is unknown whether the pain relief results from habituation to the repeated painful electric stimulation. We compared the effects of CPM and habituation on PCES-induced pain and PCES-evoked potentials and analyzed whether increased attention by a random change of electric intensities amplifies the habituation effects.