Week of Dec. 17, 2005; Vol. 168, No.
25 , p. 390
Bruce Bower
Preliminary
evidence indicates that people can quell either temporary or chronic physical
pain by learning to use their minds to reduce activity in a key brain area.
Brain-imaging
technology now enables individuals to use mental exercises to control a neural
region that contributes to pain perception, say neuroscientist Sean C. Mackey
of Stanford University and his colleagues.
Both
healthy volunteers and chronic-pain patients "learned to control their
brains and, through that, their pain," Mackey holds. "However, significantly
more testing must be done before this can be considered a treatment for chronic
pain."
The new
findings appear in the Dec. 20 Proceedings of the National Academy of
Sciences.
Mackey's
team studied 32 healthy volunteers, ages 18 to 37. First, each volunteer
reported when an adjustable heat pulse applied to a leg produced pain that he
or she rated as 7 out of 10, with 10 being equivalent to "the worst pain
imaginable." Brain imaging of participants, using a functional magnetic
resonance imaging (fMRI) scanner, showed that this level of pain was
accompanied by pronounced blood flow—a sign of intense neural activity—in an
area called the rostral anterior cingulate cortex.
Eight of
the volunteers then underwent brain training. Each reclined in an fMRI machine
that visually displayed activity changes in the person's rostral anterior
cingulate cortex. A virtual flame dimmed as activity fell and brightened as
activity surged.
While
watching this display for 39 minutes, participants tried various mental
strategies both to increase and to decrease their brain activity during brief
periods of heat-pulse application. The experimenters suggested tactics such as
focusing attention away from the pain.
By the end
of the training session, the volunteers had learned to raise or lower activity
in the critical brain area, the researchers say. The eight volunteers rated
pain much higher during robust anterior cingulate cortex activation than during
periods of lesser activity in that region.
No such
brain-related pain effects occurred for the remaining 24 participants, who were
instructed to change their brain activity when they were outside the fMRI
machine or in the machine but receiving no feedback, when they received
feedback from brain areas unrelated to pain, or when they viewed someone else's
pain-related brain activity.
Next, eight
chronic-pain patients completed anterior-cingulate-cortex training. Afterward,
each reported much less pain—often less than half as much as usual—while he or
she mentally quelled the region's activity.
Another
four chronic-pain patients used physiological feedback—so-called biofeedback—to
learn to control their heart rate, skin conductance, and breathing. None
succeeded in lessening pain.
Neuroscientist
Gary H. Duncan of the University of Montreal calls the new study "a
landmark contribution of brain imaging to pain research." It demonstrates
that self-control over activity in a specific brain region is possible, paving
the way for explorations of neural function far beyond the treatment of chronic
pain, he says.
Letters:
I'm pleased
that images are now available to prove that self-control over pain works.
Actually, I and many other moms could have helped the researchers. During
childbirth, we simply focused on various breathing techniques and discovered
that the pain became manageable or disappeared. I've continued to use these
breathing techniques in the dentist's chair for 40 years. Chronic pain is, of
course, a different situation. It is interesting, however, to wonder if practiced-breathing
and relaxation techniques would be useful for those suffering from this awful
situation. Having good science back up anecdotal evidence is surely moving in
the best direction.
Linda Mangelsdorf
Newburgh, N.Y.
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