In a recent study (Petrovic, Kalso, Peterson & Ingvar, 2002)…

In a recent study (Petrovic, Kalso, Peterson & Ingvar, 2002), subjects were exposed to a painful stimulus (heat to the hand) under three conditions: opiate medication, placebo (sugar pill) medication, and no medication. Brain scans indicated that a subject’s experience of reduced pain with the placebo is due to