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Grandmother Pain Cells?

John johnhkm at netsprintXXXX.net.au
Tue May 25 04:57:45 EST 1999


The link contains other articles concerning this ...

http://www.academicpress.com/inscight/04221999/graphb.htm

The link says ..

Neuroscientists have homed in on the nerve cells in the seat of our
consciousness that may tell us to feel the pain of being jabbed with a
needle or touching a hot stove--or even to wince when someone else is in
agony. The results, from an extraordinary experiment in patients undergoing
brain surgery, appear in the May issue of Nature Neuroscience.
      Animal experiments in the '80s found that the anterior cingulate
cortex (ACC), a region in the frontal cortex, is involved in pain
perception. Brain imaging techniques in humans confirmed this role in pain
processing, but cannot provide the kind of resolution to pinpoint how
individual cells react to sensations.
      Seizing a rare chance to delve deeply into the ACC's inner workings,
neuroscientist Bill Hutchison of the University of Toronto teamed up with
neurosurgeons to study patients who undergo a last-resort treatment for very
severe cases of depression and obsessive-compulsive disorder. The procedure
involves drilling a tiny hole in the skull and severing a bundle of nerve
fibers connecting the ACC, involved in these disorders, to other regions.
      Hutchison placed an ultra-thin electrode in the ACC of 11 patients by
slipping it into their skull boreholes before the nerve fibers were cut. He
applied various stimuli to the patients' hands, such as heat, cold, or
sticking a needle in their fingers, and, while measuring the activity of
individual ACC cells, asked them what they felt. Of 392 nerve cells
monitored, he found 11--in four patients--that responded exclusively to
pain. Some of these cells responded to pain from several stimuli, while
others responded only to specific painful sensations. This high specificity
suggests that the ACC is a central pain processing unit, says Hutchison.
      He also found three nerve cells that fired when the patients were
bracing for a pain stimulus, or when they saw the researchers inflict pain
upon themselves. This could be a cellular explanation for the saying "I feel
your pain," says Hutchison. "These aren't simply pain signaling cells," he
says, "they're much more sophisticated than just giving you an 'Ouch!'
response." The findings are "wonderful," says Catherine Bushnell, a
neurobiologist at McGill University in Montreal. The ACC, she says, "is
probably very important in telling us how to respond to pain, whether to
flight or to fight."
      --Michael Hagmann


John
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