Neuroscientists Hack Itching, Exposing a Mysterious Neural Circuit

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A key to understanding why scratching an itch feels so good.

By Michael Byrne | MOTHERBOARD

Scratching an itch doesn’t take a whole lot of brain horsepower. It’s not automated in the same sense that breathing and heart beating are, but when it comes to everyday itch-scratching it might as well be. The brain registers itching—via the same pathways that transport sensations like temperature and pain from the skin—and it naturally responds by deploying fingernails. The itch is scratched, and that feels good.

Actually, scratching an itch feels more than good. As someone that suffers from chronic eczema and spends a disproportionate amount of time in contact with poison oak, I’m something of a connoisseur of scratching and its unique, fleeting gratification. I’m a lot like a dog, if we’re being honest. I love a good scratch.

There’s more to itch scratching than one might imagine, at least from a neuroscientific perspective. It’s only been in recent years that we’ve started to isolate and identify that actual neural circuitry responsible for itching. The first identification of a nerve in the skin—any nerve—responsible for the itch sensation came in 1997. Now, researchers from the Chinese Academy of Sciences have successfully identified a neural circuit in the brain that’s thought to service this elusive sensation—a major advance. Their work is described this week in Science.

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