By Ed Ungar, Medical Tribune News Service
Using a kind of old-fashioned Pavlovian psychology and advanced
brain-imaging techniques, a British-Canadian team has found that
the brain has ``dread zones'' that not only anticipate pain, but
make it worse.
The findings have therapeutic implications for people ranging
from dental patients to chronic pain sufferers, the research
suggests.
Two researchers from Oxford, England, traveled to Canada to use
one of the seven most powerful magnetic resonance imagining (MRI)
machines in the world. The machine, which is at the John P. Robarts
Research Institute in London, Ontario, is able to image the
activity of small sections of the brain.
Twelve volunteers allowed themselves to be attached to a metal
contact -- the size of a half dollar -- that produced nonpainful and
painful sensations. The changing sensations were coordinated with
alternating red and blue lights.
After researchers flashed a blue light, subjects felt a nice
warm sensation through the contact.
``If they [the subjects] saw a blue light they were happy,''
observed Ravi S. Menon, a neuroimaging scientist at the Robarts
Research Institute's Labs for Functional Magnetic Resonance
Research and co-author of the study,
which is published in the June 18 issue of the journal Science. The
Oxford co-researchers who traveled to Canada are Alexander
Ploghaus, at the department of clinical psychology at Oxford
University in England, and Irene Tracey, at Oxford's Centre for
Functional Magnetic Resonance Imaging of the Brain.
But the happy blue light didn't last long. It was replaced by a
red one every 30 seconds. And after subjects saw the flashing red
light for about seven seconds, they would feel an average of eight
seconds' worth of a painfully hot sensation. The heat was not
enough to cause injury, but was more than enough to cause what
dentists call ``sensitivity.'' During a session, each volunteer
experienced five jolts of pain.
With each succeeding flash of the red light, subjects felt
ever-greater feelings of pain. However, the actual heat sent
through the contact remained constant.
The MRI detected three regions of the brain that registered
higher and higher metabolic activity from the time when the
flashing red light would begin to the time when heat was actually
applied. The dread zone regions were located just 1 centimeter from
the centers of the brain that are associated with direct experience
of pain. ``The two regions were communicating with each other,''
said Menon.
The researchers also found that the female subjects were tougher
than the male ones. They could stand jolts an average of 5 degrees
hotter (55 degrees Celsius) than men (50 degrees Celsius).
``Pain can be a good thing,'' Menon said in an interview. ``It
forces you to take away your hand from a hot stove. And
anticipating pain can make you avoid the stove in the first place.
But once you have inescapable pain such as a migraine headache or
back ache the pain makes things worse, not better.''
According to Menon, the study suggests that techniques such as
biofeedback may be effective against anticipating pain and thus
reduce it. Also he notes that drugs may be developed that will be
directed toward the dread zones.
Gary Rollman, a professor of psychology and specialist in pain
assessment and evaluation at London's University of Western
Ontario, said that pain researchers believe that people experience
pain on sensory, emotional and cognitive levels. ``This study fits
very well into that concept,'' observed Rollman, who was not
associated with the research. ``Those pathways which respond at the
sensory levels were not changed, but those having to do with
cognitive processes were affected.''
He said the study is consistent with the idea that
cognitive-behavioral therapy will be effective with pain
management. It may also help explain why tranquilizers help some
patients cope with pain, he added.
``The lesson from all this,'' concludes Menon, ``is that mind
can conquer matter and can certainly conquer pain.''
The research was jointly sponsored by the Medical Research
Council of the U.K. and the Medical Research Council of Canada.
