Contributed by Billy Ethridge
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There is evidence that any pain that lasts more than a few minutes will leave a trace in the nervous system, says neuroscientist Terence Coderre. It’s this memory of pain, which exists at the neuronal level, that is critical to the development of chronic pain. (Credit: iStockphoto)
MCGILL (CAN) — Researchers have discovered that it may be possible to ease chronic pain by erasing memories stored in the brain.
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It has long been known that the central nervous system “remembers” painful experiences, that they leave a memory trace of pain. And when there is new sensory input, the pain memory trace in the brain magnifies the feeling so that even a gentle touch can be excruciating.
“Perhaps the best example of a pain memory trace is found with phantom limb pain,” suggests neuroscientist Terence Coderre of McGill University. “Patients may have a limb amputated because of gangrene, and because the limb was painful before it was amputated, even though the limb is gone, the patients continue to feel they are suffering from pain in the absent limb.
“That’s because the brain remembers the pain. In fact, there’s evidence that any pain that lasts more than a few minutes will leave a trace in the nervous system.”
It’s this memory of pain, which exists at the neuronal level, that is critical to the development of chronic pain. But until now, it was not known how these pain memories were stored at the level of the neurons.
Recent work has shown that the protein kinase PKMzeta plays a crucial role in building and maintaining memory by strengthening the connections between neurons.
In the new research, published in the journal Molecular Pain, Coderre and colleagues have discovered that PKMzeta is also the key to understanding how the memory of pain is stored in the neurons. They were able to show that after painful stimulation, the level of PKMzeta increases persistently in the central nervous system (CNS).
Even more importantly, the researchers found that by blocking the activity of PKMzeta at the neuronal level, they could reverse the hypersensitivity to pain that neurons developed after irritating the skin by applying capsaicin—the active ingredient in hot peppers. Moreover, erasing this pain memory trace was found to reduce both persistent pain and heightened sensitivity to touch.
Coderre and his colleagues believe that building on this study to devise ways to target PKMzeta in pain pathways could have a significant effect for patients with chronic pain.
“Many pain medications target pain at the peripheral level, by reducing inflammation, or by activating analgesia systems in the brain to reduce the feeling of pain,” says Coderre.
“This is the first time that we can foresee medications that will target an established pain memory trace as a way of reducing pain hypersensitivity. We believe it’s an avenue that may offer new hope to those suffering from chronic pain.”
The research was supported by grants from Canadian Institutes of Health Research, the Louise and Alan Edwards Foundation, the National Institutes of Health, and an Astra-Zeneca/AECRP fellowship.
More news from McGill University: www.mcgill.ca/newsroom/
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Contributed by Billy Ethridge
September 6, 2008, about 1:50am, I had a massive hemorrhagic stroke at home. Like millions of other stroke "survivors", my life has changed irreversibly.
I am not a physician or rehabilitation therapist or other medical professional, though I have greatly benefited from kindness of some very skilled ones.
A number of years ago, I did PhD work -- but no dissertation, so no PhD -- in Philosophy (Logic and Linguistic Analysis) at UCSD, with a strong mathematical background. At age five I started judo, and subsequently studied Aikido and Tang Soo Do, and other martial arts. I am also a musician -- singer and instrumentalist (primarily a guitarist and harmonica player). Over the years (I was born in 1948), I have created music & lyrics, poetry, and other writings.
I summarize these elements of my life because everything in me, and what I have learned from my rehabilitation, conversations with patients and medical professionals, and extensive reading, tells me that: (1) the stroke I have had has been THE single most transformative event in my life; and (2) this transformation has been an overwhelmingly positive experience for me even in the midst of dramatic neurophysiological demands.
Stroke Revelations is intended to provide personal reflections about what is possible to those of us who have entered the "event" of a stroke and came out alive. This blog is dedicated to all people whose consciousness has been overwhelmed, from whatever avalanche of neurophysiological reasons, and did not make it to the "other side".
"Every human being is the author of his own health or disease." ~Buddha
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