FRIDAY, Sept. 24 (HealthDay News) -- You burn your hand on a hot
stove. You grab that hand with the other, and sometimes the pain
goes away. Ever wonder why?
British researchers did, and their unusual study suggests that
you can reset your brain's image of your body to help eliminate
that pain.
The researchers found that they were able to significantly
decrease the levels of pain in the hands of people who thought they
were experiencing extreme heat. Their method: they told the
participants to touch three fingers on one hand to three fingers on
the other.
The effects of the "self-touch" approach sounds more than a
little peculiar. But it's a tool that "might create new
possibilities for pain treatments," said study co-author Marjolein
P.M. Kammers of University College London's Institute of Cognitive
Neuroscience in the United Kingdom.
At issue is the brain's "body representation," which is a kind
of blueprint of your body parts and where they are in the world.
"This sounds simple, but it has been shown that we use different
representations depending on what we want to do with our body at a
certain moment and that these representations can change over
time," Kammers said.
Researchers have directly linked phantom limb pain -- in which
amputees feel pain in an arm or leg that is no longer there -- to
the body representation system.
"One hypothesis is that phantom limb pain after amputation is due to mismatch between the way that the body really is (without a limb) and the way the brain represents it to be (as it was with all limbs intact)," Kammers said. "Once the body representation is appropriately updated, the phantom limb pain is often reduced."
In the new study, researchers wanted to find out if clutching
your hands when they're injured may beneficially disrupt the body
representation system. Could it fool the brain?
"Pain is not just a signal from the body reaching the brain," Kammers said. "It is modulated in the brain according to how the brain represents the current state of the body."
The researchers didn't want to actually hurt anyone, so they
took advantage of a strange phenomenon: if you put your index and
ring fingers in warm water and your middle finger in cool water,
you will think your middle finger is burning.
The researchers used the illusion to fool people into thinking
their middle fingers were extremely hot and then removed their
hands from the water. Some participants touched fingers from one
hand to another, while others touched someone else's hand.
Those who touched all three fingers to the same fingers on the
other hand felt 64 percent less painful heat, the investigators
found.
"Self-touch caused the integration of both hands together into a coherent body representation, which caused a reduction in heat pain," Kammers said.
The study shows that "we can think creatively about how to treat
pain by changing what the brain understands to be true," said Beth
Darnall, an assistant professor at Oregon Health & Science
University who is familiar with the study findings. "We can trick
the brain out of pain by making it believe certain things about
itself."
Doctors already use an approach called "mirror therapy" to
reprogram the brains of amputees who suffer from phantom limb
pain.
More widespread use of fooling the brain to treat pain is "a
little bit down the road," Darnall said, but she thinks studies
like this one are paving the way.
The study findings were published online Sept. 23 in the journal
Current Biology.
More information
The U.S. National Library of Medicine has details on
phantom limb pain.