Brain activity could one day help physicians to monitor pain, for which there is no reliable physiological test.

Using a type of magnetic resonance imaging that shows when certain parts of the brain are activated, Tor Wager at the University of Colorado Boulder and his colleagues started out by scanning the brains of 20 volunteers as they experienced warm to painfully hot sensations on their arm. They used these data to find a pattern of neural activation and deactivation that consistently appeared when the volunteers were exposed to painful heat. Further tests showed that this signature could discriminate physical pain from other stimuli, such as social pain and recollections of pain. The signature was reduced by analgesics. Such patterns could one day lead to more-objective assessments of pain.

N. Engl. J. Med. 368, 1388–1397 (2013)