Research: NICE WHEN YOU STOP

According to the popular saying, difficult tasks are like banging your head against a brick wall: it's nice when you stop. A team led by Ray Dolan at the Wellcome Department of Imaging Neuroscience at University College London have now found, using brain imaging, why this is so.

The new research suggests that the brain treats relief from pain and natural reward in a similar way. In addition, people suffering prolonged pain can 'learn' to predict relief, something that could affect how they deal with pain in the future.

The group tested the effect of Pavlovian conditioning – where an arbitrary cue becomes associated with a painful stimulus, so eventually the cue triggers a response even without the stimulus. They exposed people to prolonged pain (tolerable to the subjects) and then, after a visual cue, gave them either pain relief, extra pain or nothing.

Half the time, though, the cue was false, so subjects constantly had to update their expectations of what was coming next. Using brain imaging, the researchers could then see what effect expectation of pain relief had, even when it didn't actually occur.

The expectation of relief activated reward-like pathways in the amygdala and midbrain, while 'aversive' signals were activated elsewhere in the brain when the relief failed to materialise.

Unravelling how psychological phenomena affect brain activity could be useful in creating more effective pain relief or techniques to manage chronic pain.

External links

• Seymour B et al. Opponent appetitive–aversive neural processes underlie predictive learning of pain relief. Nat Neurosci 2005;8(9):1234–40.