Researchers have developed a potentially powerful new tool that allows patients to fight pain by literally thinking it away. Volunteers put inside a functional magnetic resonance imaging (fMRI) machine were able to control the activity of a brain region responsible for pain perception, suggesting that the technology may someday provide a drug- and side-effect-free way to calm troubled nerves.
People have been using a technique called biofeedback for decades to control automatic body functions such as heart rate and muscle tone. By focusing on their pulse rate on a monitor, for example, people can actually lower it, in an attempt to relax. People have also learned to modulate their own brain waves, say, to move computer cursors. Christopher deCharms, the chief executive of Omneuron, a Menlo Park, California-based company developing clinical applications for functional brain imaging, wondered whether people could learn to dial up or down activity in a particular brain region to produce a therapeutic effect.
To find out, deCharms teamed up with pain specialist Sean Mackey and his colleagues at Stanford University. The researchers placed eight healthy volunteers one at a time in an fMRI machine, which maps the brain by region, and had them hold a very hot metal cube. A virtual reality display inside the machine depicted a flame whose intensity reflected the activity of their rostral anterior cingulate cortex (rACC), an arc-shaped brain region that previous studies had implicated strongly in pain perception.
Using the fiery feedback, the subjects learned to raise or lower the activity of the rACC by alternatively focusing on or away from the pain, or thinking of the heat as neutral or frightening. The better they controlled their rACC activity, the better they controlled the self-reported intensity of their pain. By contrast, volunteers who were asked to change their rACC activity without fMRI feedback, or with sham feedback from another brain region or from another volunteer's rACC, could not effectively do so, and also failed to control their pain, the researchers report online this week in Proceedings of the National Academy of Sciences. "We feel this is very strong evidence that the real-time fMRI information was necessary for this effect," deCharms says. The team also saw improvement with eight chronic pain patients who were taught to control activation of their rACC.
"It's a really interesting and potentially important finding," says Robert Dowman, a pain researcher at Clarkson University in Potsdam, New York. "This gives us another possible modality for [chronic pain] therapy that doesn't involve drugs." But don't expect a home version any time soon. Dowman notes that the $2 million price tag of fMRI machines will likely limit the method's practicality for the foreseeable future.