Why don't we laugh when we tickle ourselves? What kind of feelings do we have if someone tickles us? A recent study on mice answers these questions.
New research in mice has shown that an important factor is missing when the process is tickling your hands. Neuroscientists at the Humboldt University in Berlin found that when mice rub themselves, their reactions are different when others do so.
When the researchers tickled the mice, they found that the part that characterizes the sensation of touch in her brain (the somatosensory system) was active.
What is the missing link?
Neurologist Michael Brecht (lead author of the study) says this is caused by "self-touch inhibition, which inhibits self-tickling." Since the human response to tickling has been very similar with mice, this means that we do not associate any kind of self-touch with tickling sensation, and therefore do not get the same reactions unlike what happens when someone tickles us.
"If we tickle ourselves, the brain interprets the sense of self-touch as something that does not pose any kind of threat," explains psychologist Michael Titze of the Humancare Center in Germany.
Fear and suspense
Therefore, because we do not pose a threat to ourselves, another factor is needed in order for tickling to be effective, which the researchers called "Nervenkitzel" to provoke a sense of fear and suspense, "which is provided by others tickling.
The mice whose reactions were studied showed a freeze of movement, discomfort and tension when tickled, a reaction that is close to children's behavior. Contrary to what they show enjoyment and laughter when tickling, they actually hide an opposite sense of anxiety and cannot afford to feel stressed by that tickle, so they try to escape because we associate the tickle with some sort of imaginary attack.
“Psychologically, tickling leads to an overlap between two opposing signals of approaching and escaping,” says Titze. Neurologically, we feel comfortable and pain at the same time, leading to stress expressed in uncontrollable laughter.
But why are you laughing?
Sometimes, a sense of tickling can indicate a risk to our bodies, especially parts of the body that contain a lot of neurons, such as the abdomen - or the part exactly opposite the stomach - and at the armpits and upper thigh, these are the most sensitive places for tickling.
But once the brain realizes that a "tickle attack" is not a threat, we get rid of stress by laughing and it may even be as much as a mixed laughter crying, because laughter is a natural analgesic of stress, which leads to restoring balance, reassurance and happiness.
The "expected laughter" is also part of the tickling feeling. Even thinking about tickling can make us laugh. The study found that the same part of the rat brain that is activated when tickling occurs is also stimulated when tickling is predicted before the tickling process itself occurs.
Scientists believe that when we laugh proactively in the context of play and fun, it is a sign that there is a positive readiness for attacks that may occur during the handshake So try not to laugh the next time someone intends to tickle you, and you probably won't discover what is the most sensitive place in your body to tickle.