This new biofeedback technique might also turn out to be useful for treating other conditions.
Biofeedback techniques based on electroencephalogram (EEG) recordings of brainwave patterns, in which electrodes are placed on the scalp, are used with some success to treat epilepsy and attention problems such as ADHD.
But no one has found a way to use this method for controlling pain in people, says Peter Rosenfeld of Northwestern University in Chicago, one of the pioneers of biofeedback.
Twenty years ago Rosenfeld found that he could change the pain threshold in mice by training them to alter their brainwave patterns through a process called conditioned learning, where an altered brainwave state was rewarded by direct stimulation of the reward centres in their brains. Since this meant placing an electrode into the brain, however, his team never tried the technique on people.
Now Fumiko Maeda, Christopher deCharms and their colleagues at Stanford University in California have tried showing people real-time feedback from a functional magnetic resonance imaging (fMRI) scanner.
The difference between EEGs and fMRI, says Rosenfeld, is that fMRI allows you to show volunteers how much activity there is in specific areas of their brains. "From scalp recordings, you don't really know what you are recording," he says.
The eight volunteers saw the activity of a pain-control region called the rostral anterior cingulate cortex represented on a screen either as a flame that varied in size, or as a simple scrolling bar graph.
This brain region is known to modulate both the intensity and the emotional impact of pain. During the scans the volunteers had to endure painful heat on the palm of their hand. They were asked to try to increase
Contact: Claire Bowles