(RATS/ANIMAL SCIENCE) Not a fan of rats? This new study might change your mind!

Neuroscientists are tickling rats in an attempt to demonstrate the similarities between rats and humans when they’re tickled. Believe it or not, the rats loved being tickled so much, they would let out the rat-equivalent of laughter, jump for joy, and even seek out the scientists’ hands for more. But just like with humans, you can’t tickle rats when they’re not in a good mood.

While the research might all sound like fun and games, the study actually has several implications for human psychology, and helps explain how moods affect behavior as well as the importance of touch when establishing social bonds.

Continue reading to learn more about what these striking similarities between humans and rats suggest, and how the study is an importantnt contribution to the world of psychology. — Global Animal

Rats laugh when they are tickled and during playtime. Photo credit: data.whicdn
Rats laugh when they are tickled and during playtime. Photo credit: data.whicdn

New York Times, James Gorman

There’s just something about a rat jumping for joy when it’s been tickled that can change your whole outlook on rats, and neuroscience.

For one thing, it gives me new faith in people to think that accomplished researchers spent time tickling their experimental subjects. And the similarity of rats to humans in the tickling realm is pleasantly bewildering.

And I’m glad that the experiments have implications for human psychology, how moods affects behavior, and the importance of touch in forming social bonds.

But honestly, the research could have fallen flat, and the attempt would still have perked me up, particularly by the evidence of how much fun the rats were having.

Not only did they seek out the researchers’ hands to get tickled, and emit ultrasonic calls that are considered the rat’s equivalent of laughter, they also made joyful leaps.

That’s English for freudensprungen, the common, and completely wonderful, scientific term for the behavior, as observed in many animals.

Other great words in tickling research are gargalesis — the kind of vigorous touch that induces laughter, and knismesis, defined in the paper the researchers published in the journal Science, as “non-laughter-inducing light touch.” Unlike most of the science covered in the news, you can try this at home.

Still, why tickle rats, other than that it seems that a good time was had by all?

The biggest reason is that tickling is a profound puzzle that engaged both Aristotle and Darwin, as pretty much everything did, as well as more recent scientists.

As Michael Brecht and Shimpei Ishiyama of the Bernstein Center for Computational Neuroscience in Berlin point out in their report, tickling raises many questions. We don’t know why it evolved, what purpose it might serve and why only certain body parts are ticklish. And what about that disappointing and confounding truth that all children and scientists must grapple with: You can’t tickle yourself.

The researchers were also inspired by earlier studies. “ ‘Laughing’ Rats and the Evolutionary Antecedents of Human Joy?” published in 2003 in Physiology & Behavior, reported that rats would emit ultrasonic calls when tickled. Ultrasound is too high for humans to pick up. We can hear sound waves up to a frequency of about 20 kilohertz. Rats giggle at about 50 kilohertz.

Those calls, along with the ability to record brain activity while playing with the rats, allowed a deeper investigation of rat tickling. The researchers first accustomed young rats to play and tickling, which the rats would invite.

“They are very eager to be tickled,” said Dr. Brecht.

Photo Credit: NY Times
Photo Credit: Shimpei Ishiyama & Michael Brech via the New York Times

The scientists used electrodes implanted in the rats’ brains to see what was going on when they were tickled, particularly in an area called the somatosensory cortex, where physical touch is processed. The electrodes didn’t seem to limit the rats’ interest in play and tickling, or their positive calls. Dr. Brecht said they did not pick up any alarm calls from the rats.

The scientists found that tickling and play, which involved chasing a researcher’s hand, both caused the same ultrasonic calls and the same brain cells to be active. The scientists also stimulated those cells electrically, without any tickling or play, and got the same calls.

And they found that you can’t tickle rats when they are not in a good mood, something that is also true of people.

When the rats were placed on a platform, or in bright lights, situations known to make the animals fearful, they didn’t respond to tickling.

What it all adds up to is that the researchers did not merely locate the place in the brain where the tickling response occurs, they also saw the effect of a change in mood on this very basic if mysterious process.

The brain mechanisms of how moods affect behavior are little understood, Dr. Brecht said, and learning more about them would be very important in psychology.

The link to play and emotion in an area of the brain that processes touch is also intriguing, the researchers wrote. And the similarity of tickling in rats and humans is, Dr. Brecht said, “amazing.” They even have similar areas that are susceptible for unknown reasons, including the soles of their hind feet, but not of their forepaws.

That similarity suggests that tickling is evolutionarily very ancient, going back to the roots of touch as a way to form social bonds in the ancestors of rats and humans.

“Maybe,” Dr. Brecht speculated, “ticklishness is a trick of the brain to make animals or humans play or interact in a fun way.”

More New York Times: http://www.nytimes.com/2016/11/11/science/tickling-rats-neuroscience.html

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