A ‘switch’ in the brain that shuts down pain discovered by scientists



Neuron cells in the central amygdala of a mouse brain. Red, magenta and yellow cells (but not green or blue) are parts of a collection of neurons called the CeAga that has potent pain-suppression abilities. (Credits: Duke University / SWNS) A ‘switch’ in the brain that shuts down pain has been discovered.

Scientists have found a small area of the brain in mice that can ‘profoundly’ control the animals’ sense of pain.

They said the brain centre that turns pain off, not on, is located in an area where few people would have thought to look for an anti-pain centre, the amygdala, which is often considered the home of negative emotions and responses, such as the ‘fight or flight’ response and general anxiety .

Study senior author Professor Fan Wang, of Duke University in the United States, said: ‘People do believe there is a central place to relieve pain, that’s why placebos work.

‘The question is where in the brain is the centre 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 pain. Whereas this one centre can turn off the pain by itself.”

The latest study is a follow-up to earlier research in Prof Wang’s lab looking at neurons that are activated, rather than suppressed, by general anaesthetics.

Researchers found a region of the brain in mice that controlled the feeling of pain (Photo by Smith Collection/Gado/Getty Images) In a 2019 study, the team found that general anaesthesia promotes slow-wave sleep by activating the supraoptic nucleus of the brain.

But sleep and pain are separate – an important clue that led to the new finding, published online in the journal Nature Neuroscience.

The researchers found that general anaesthesia also activates a specific subset of inhibitory neurons in the central amygdala, which they have called the CeAga neurons.

Mice have a relatively larger central amygdala than humans, but Prof Wang said she had no reason to think that man has a different system for controlling pain.

Using technologies that Prof Wang’s lab has pioneered to track the paths of activated neurons in mice, the team found the CeAga was connected to many different areas of the brain – a finding Prof Wang described as ‘a surprise..’

By giving mice a mild pain stimulus, the researchers could map all of the pain-activated brain regions.

They found that at least 16 brain centres known to process the sensory or emotional aspects of pain were receiving inhibitory input from the CeAga.

Prof Wang said: “Pain is a complicated brain response. It involves sensory discrimination, emotion, and autonomic responses. Treating pain by dampening all of these brain processes in many areas is very difficult to achieve.

‘But activating a key node that...

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