Original article written by Annie Lennon (MAY 19, 2020 2:47 PM PDT)

Researchers at Duke University have found that a small group of cells in the brain may be able to regulate our sense of pain. Using mouse models, they found the cells in the amygdala.

The findings are a follow-up to earlier research investigating how neurons are activated by general anesthetics. In 2019, the same researchers found that general anesthesia promotes slow-wave sleep as it activates a specific subset of neurons in the central amygdala, known as CeAga neurons. 

Using various technologies, the researchers tracked the pathways of neurons activated in mice after giving them a mild pain stimulus. In total, they found that at least 16 areas of the brain known to process sensory and emotional aspects of pain received inhibitory signals from the CeAga. 

“Pain is a complicated brain response,” says senior author of the study, Fan 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.”

Next, the researchers used a technology known as optogenetics, that activates various parts of the brain with a ‘light’, to activate the CeAga neurons. In doing so, they found they could turn off self-caring behaviors in mice when they feel uncomfortable, such as licking their paws. Reducing the activity of these neurons caused the mice to immediately revert to comfort-seeking behaviors. 

Furthermore, they found that low doses of anesthetic drug ketamine, known to allow sensation but block pain, also activated the CeAga cells, and could not function without them.

Now, the researchers intend to identify the gene responsible for this process, and thus a drug target, so may then develop treatments to relieve pain using this mechanism. 

Sources: Science Daily, Medical Xpress, Earth.com

Reference:

“Researchers Find Brain Cells That Shut Down Pain.” LabRoots, 19 May 2020, http://www.labroots.com/trending/neuroscience/17655/researchers-brain-cells-shut-pain#. Accessed 20 May 2020.

I think it is very interesting that pain is actually a chain linked reaction that can lead to tissue damage. The fact that our body sends hormone and signals to the brain to trigger that feeling of ‘pain’ is very interesting. Thinking about it now, it is difficult to describe what pain exactly feels like without using the word ‘painful’. I think the human body is very, very fascinating because the past trillion years of human existence on earth, we still discover new hormones, cells, diseases every day… I wonder why the body would trigger the signal of pain if the body also possesses a cell able to lessen pain.. Then why would the body trigger pain signals? To stop the person from injuring themselves more by exposing themselves more and more to bacterial and virus infections?

-Joanna Kim, May 20, 2020 , 11:44PM KST