Suffering from pain? Scientists locate ‘switch’ in the brain that shuts down pain

Scientists may have found a way to turn pain off for good. Researchers at Duke University in North Carolina, US, have found a small area of the brain in mice that can control the animals’ sense of pain.

“Somewhat unexpectedly, this brain center turns pain off, not on,” researchers said in a press release. The team said the so-called ‘switch’ is located in the amygdala, which is often considered the home of negative emotions and responses, like the fight or flight response and general anxiety.

“People do believe there is a central place to relieve pain, that’s why placebos work,” senior author Fan Wang said. “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. 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.”

For the study published in the science journal Nature Neuroscience, the researchers gave the mice a mild pain stimulus and proceeded to map all the pain-activated brain regions. They discovered that at least 16 brain centres known to process the sensory or emotional aspects of pain were receiving inhibitory input from the CeAga (a specific set of inhibitory neurons in the amygdala).

“Pain is a complicated brain response,” Wang said. “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.”

The researchers then used technology to activate a small population of cells in the brain and found they could turn off behaviours the mouse exhibits when it feels uncomfortable. For example, paw-licking or face-wiping behaviours were “completely abolished”. “It’s so drastic,” Wang said. “They just instantaneously stop licking and rubbing.”

Going forward, he said the researchers are going to look for drugs that can activate only these cells to suppress pain as potential future pain killers.