Scientists have discovered that the brain's response to pain appears to follow a path similar to that of the pleasure response. The findings could one day lead to better treatments for people suffering chronic pain.

Using a brain scanning technique called fMRI researchers monitored the brain's response to painful stimuli in eight healthy male volunteers. Heat probes were placed on the back of the men's hands.

During the first round of the experiment, the probe was at a temperature that produced no pain. During the second round, the probe was kept at 46 degrees Celsius (114 degrees Fahrenheit) for 25 seconds -- enough heat to generate pain.

The brain response generated by the two different temperatures was different. And the painful stimuli activated the brain's "reward" circuitry, which has previously been shown to respond to drugs, pleasant tastes and other pleasurable stimuli.

The findings provide insight into a circuitry that may provide a basis for understanding 'suffering' as a response to chronic pain. Chronic pain affects 30% to 50% of the adult population in the US.

Our understanding of how pain is differentially interpreted in the central nervous system of humans has been significantly advanced with the ability to image neural pathways or circuits involved in evaluating an experimental or clinical painful stimulus.

Neuron December 6, 2001;32:927-946