Scientists Trace Giggling, Ticklish Rats to Good Mood and 'Tickle Center' in the Brain
Ever wondered why humans burts into an involuntary laugh when tickled? A new study reveals that the same effect happens on rats too, and it may be traced to brain activity.
According to a study published in the journal Science, rats who are in a good mood like to be tickled. When tickled, the animals blurt out high-pitched squeaks or ultrasonic vocalizations, which according to Jaak Panskepp in a 1999 study, can be attributed to positive behavior such as playing.
The study shows that the rat's reaction to tickling when they are in a less anxious situation is a product of an activity in the somatosensory cortex, the part of the rat's brain where the sense of touch is involved.
The researchers also revealed that the intensity of the rats' ticklishness depends on the emotional situation. Those who are in a happy situation and dark light, the rats produced ultrasonic vocalizations and even chased the tickling hand as an indication of joy. Meanwhile, those tickled in anxious situations and bright light do not produce much high-pitched squeaks.
“Science has been obsessed with bad things” said Shimpei Ishiyama, lead author of the study. “It’s important to also study positive motivations like happiness or fun.”
The study could help humans in understanding the origins of play and laughter among other species and our own, Popular Science reports.
“This is the only deep scientific approach we currently have to understanding the evolutionary sources of our own emotions, which are very important for deepening psychiatric understanding and treatment of affective disorders," Panskepp, who was not involved in the study, said.