In what may be the most fun experiment in history, scientists from the Bernstein Center for Computational Neuroscience are exploring the neural origins of ticklishness. To do this, they've enlisted the help of some cute participants: lab rats.
Like humans, rats make noise when they're tickled, according to a National Geographic video about the research. It's not exactly a laugh, though. It's too high-pitched for humans to hear, but when it's dropped to a lower frequency, it sounds like a squeak. And unlike many humans, they actually seem to enjoy tickling, chasing hands that tickle them after they let go.
By recording rats' brain activity while they were tickled, the researchers noticed that the neurons in the trunk of the somatosensory cortex — which is used for perception of touch — were active during tickling. To double check the theory that this is where ticklishness comes from, they electrically stimulated the region and found that the rats did indeed emit their signature tickling noise.
The interesting part, though, is that when the rats were in a bright, high-up, or otherwise stressful place, they didn't make that squeak. The authors of the paper, published in Science, think the rats' brains may suppress enjoyment in these situations so they can be on the alert for predators.
Check out the video below to watch rats being tickled for the sake of your education.
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