A team of German researchers has discovered why we laugh uncontrollably when we are tickled – and the answer has nothing to do with entertainment.
Laughter in animals is a form of social bonding based on a primordial reflex to tickling, but human laughter has come a long way from these playful roots. According to scientists at the University of Tuebingen, tickling activates the region of the human brain that is responsible for anticipating pain. This is why people sometimes react violently when tickled.
Researchers say that laughter caused by tickling is part of a defense mechanism by which the “victim” gives a signal of submission. Scientists believe that our response to tickling is dating from the earliest times of human evolution, close to the period when man developed self-awareness.
Interestingly, parts of the body that are most susceptible to tickling are also the most vulnerable, so researchers at the University of Tuebingen have developed the hypothesis that parents would tickle the children to train to react to danger, and laughter generated by tickling is a method by which we recognize losers.
Researchers have used the 30 volunteers who have been scanned by a device with magnetic resonance imaging (MRI) to understand why tickling causes laughter and laughter is similar if one generated by a joke or a funny situation.
The scientists asked study participants to laugh at something that seems funny, then they tickled feet. Meanwhile, volunteers were monitored using brain magnetic resonance apparatus.
Researchers found that both tickling and laughter usually leads to activation of a part of the brain known as Roland or operculated operculated frontoparietal, the region that controls facial movements and vocal and emotional reactions.
However, researchers realized that laughter caused by tickling the ordinary and are different because tickling stimulates the hypothalamus region of the brain that controls body temperature, hunger, fatigue and sexual behavior.
This region of the brain controls people’s instinctive reactions, like defending reactions, the reaction known as “fight or flight”.
For this reason, researchers understand why some people start laughing when they are only threatened to be tickled.
“When someone tickles actually amielinice stimulate nerve fibers that cause pain,” says Dr. Alan Hirsch, founder of the Smell & Taste Treatment and Research Foundation in Chicago.
This explains why you can not tickle yourself – the brain is aware that there is no need to produce a response to this action.
PS: also rats are laughing when they are tickled