Are There Objective Measures for Pain?

The paper reported the results of a sequence of 4 studies on a total of 114 healthy subjects that examined whether changes on fMRI correlated with pain complaints. The first study examined whether certain brain patterns occurred in response to heat-induced pain and whether these patterns could be separated from those induced by non-painful warmth, pain anticipation, and pain recall. The second sought to determine if this pain pattern caused by heat could be separated from brain patterns caused by stimuli of 6 temperatures that induced warmth without pain. The third study compared the brain responses of subjects who had experienced the thermal pain to fMRI patterns of what the authors considered to be "social pain”—brain reactions to images of an ex-partner in participants who had recently experienced a romantic breakup. The fourth looked at whether there was a change on fMRI when subjects experiencing heat-induced pain received the analgesic agent remifentanil.