Have you ever noticed that when someone near you yawns, you yawn too? Scientists have noticed the same reaction with scratching, and they are using mice to test this theory.
When mice see another mouse scratching, they scratch too. Zhou-feng Chen is a neuroscientist at the Washington University of Medicine in St. Louis, Missouri. He examined brains and noticed that mice often scratch after watching another mouse next to them scratch. He and other researchers designed a study to find out whether scratching is contagious or not.
They put itchy mice within sight of non-itchy mice. What they found was that the non-itchy mice would start scratching after watching the itchy mice scratch. To compare, they put two non-itchy mice right next to each other to see what would happen. They found that neither one scratched after looking at the other. Sometimes, a mouse didn’t even have to be present to make another mouse scratch. This means that a mouse could have been watching a video of another mouse scratching, which triggered them to scratch.
When a mouse’s brain is triggered, it starts to scratch. Research suggests several brain regions play a role in contagious scratching. Scientists believe that a pair of nerve cell clusters, called suprachiasmatic nuclei, are involved in the scratching trigger of the mice. They used two kinds of mice, one was normal and the other had a brain molecule called GRP. GRP is a small brain molecule that makes the mice want to scratch after watching others scratch. The mice without GRP did not scratch, although they do scratch when they get tickled.
Scientists still don’t know how this mice study compares to human behavior. But in the future, Chen’s research might help people who itch a lot.
[Source: Science News For Students]