When the research team touched the rat’s abdomen, the rat tickled and emitted an ultrasonic “squeak”. Courtesy of Michael Brecht
In the photo, the rat tickles and smiles. while emitting ultrasonic sounds so strong that people cannot hear them.
In July, Professor Michael Brecht’s team at the Humboldt University of Berlin (Germany) measured brain activity when rats were tickled or played and announced a study showing that “gray matter around water pipes” in the brain is essential for play.
For one to two weeks, the research team allowed the rats to live comfortably and happily in the experimental box. The lights were dimmed and the rats were touched at least once a day to get used to human touch. The research team then gently tickled the backs and stomachs of the mice.
They also played hide-and-seek, chasing a mouse with their hand and making the mouse voluntarily run towards their hand. The research team recorded the rats’ brain activity using electrodes previously implanted in the rats’ brains while the rats were tickled and played.
As a result, the research team found that the gray matter around the plumbing in the brain was highly activated when the rat was tickled. Conversely, when this area was suppressed, the mice stopped playing and laughing.
In the same experiment, in bright light that made the rats anxious, the rats played less and their laughter and gray matter response were reduced. The research team explained that gray matter around plumbing plays a critical role in play and laughter.
The periductal gray matter, located in the midbrain, is known to be involved in the control of instinctive behavior in response to threatening stimuli. The results show that play and laughter are also instinctive. Professor Michael Brecht stated: “We will study whether the gray matter around the plumbing plays a decisive role in the play of other mammals.”
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Dong’s Children’s Science, September 1 issue. (Science News) Ticklishly laughing rats have revealed the area of the brain responsible for laughter!