The first of Buddhism’s Four Noble Truths states that all life is suffering. While the Buddha wasn’t just talking about physical pain with his teachings, good old fashioned bodily pain is very much a daily fact of life for pretty much all of us. Can you remember a single day when you didn’t experience even the slightest moment of pain? Pain, as the Buddha said, is pretty much an unavoidable part of the human experience.
What if, though, there was a way to completely “turn off” the sensations of pain in your body, not just numb them using opioids? It sounds far fetched, but researchers from Duke University have made a groundbreaking neural discovery in the brains of mice that may one day lead to the end of pain altogether.
They’ve uncovered a small region of the brain that appears to have near-absolute control over bodily feelings of pain. However, this area can only turn pain off, not on. Obviously, a lot more research on this matter is needed among humans, but the study’s authors say there is no reason to believe our brains are structured any differently.
As if all that wasn’t fascinating enough, this anti-pain center is located in a region of the brain not typically associated with pain at all, the amygdala. This area is classified as the “home” of negative emotions and responses, such as overall anxiety or the fight or flight response.
“People do believe there is a central place to relieve pain, that’s why placebos work,” explains senior author Fan Wang, the Morris N. Broad Distinguished Professor of neurobiology in the School of Medicine, in a university release. “The question is where in the brain is the center that can turn off pain.”
“Most of the previous studies have focused on which regions are turned ON by pain,” Wang adds. “But there are so many regions processing pain, you’d have to turn them all off to stop the pain. Whereas this one center can turn off the pain by itself.”
Professor Wang is no stranger to studying brains and pain. Just last year he published a study that found general anesthesia activates a certain set of neurons that promote slow-wave sleep. It was that research that paved the way for this breakthrough; this time around researchers noticed that anesthesia also activates a subset of neurons located in the central amygdala. They’ve named these neurons CeAga (CeA = central amygdala, ga = general anesthesia).
Mice do have bigger amygdalas than people, but again, the study’s authors have found no evidence that our brains function differently.
So, using the latest technology, the research team tracked the path of those CeAga neurons through the brain when activated. They were surprised to see that the neurons traveled all over the mice’s brains. After giving the mice a mild pain stimulus, it was determined that the CeAga neurons were basically “blocking” feelings of pain across at least 16 different brain areas known to process either the sensory or emotional sensations of pain.
“Pain is a complicated brain response,” Wang explains. “It involves sensory discrimination, emotion, and autonomic (involuntary nervous system) responses. Treating pain by dampening all of these brain processes in many areas is very difficult to achieve. But activating a key node that naturally sends inhibitory signals to these pain-processing regions would be more robust.”
On a behavioral level, what happened to the mice when the CeAga neurons were artificially activated was extraordinary. The mice stopped showing any signs of discomfort or pain. As soon as the “flip was switched,” the mice stopped wiping their faces or licking their paws, which are common outward signs of agitation or pain among mice.
“It’s so drastic,” Wang describes. “They just instantaneously stop licking and rubbing.”
Conversely, when the CeAga neurons were switched off, or just “dampened” a bit, the mice went right back to appearing in pain or discomfort.
Now, the study’s authors are hoping to develop a drug that activates CeAga neurons and blocks pain without all the side effects associated with current pain suppressors like opioids.
Is a world completely free from physical pain on the horizon? It’s a thought-provoking notion, but one that doesn’t seem so crazy in light of these discoveries. No one enjoys pain, but it’s still a fundamental aspect of being human and a major indicator of external stimuli. Ask yourself, outside of extreme scenarios (broken bones, a bad cut) would you want to be completely numb to pain?
The full study can be found here, published in Nature Neuroscience.
John Anderer is a frequent contributor to Ladders News.