The neuroscience of tickling: Why are we so ticklish?

Tickling has puzzled people for centuries, prompting questions such as why certain touches make us laugh or squirm. Recent neuroscience research offers intriguing insights into the brain's response to tickling, suggesting that the phenomenon is more than just a playful annoyance.

What is ticklish?

Tickling actually refers to two different sensations. The first is a light touch to the skin, similar to the sensation of hair touching the neck or feathers gliding down the hand. This is called knizmesis, a mild itchy sensation that may make you want to brush away the source or scratch the area. Knismesis is not usually laughable; it's more like an itch.

The second type of tickling, known as gargalesis, is more intense and usually causes laughter and squirming. Gargalosis occurs when someone constantly presses on certain sensitive areas of your body, such as your ribs or armpits. This type of tickling can be both pleasurable and irritating, and it is this sensation that has been the focus of many scientific studies.

Why are we ticklish?

The science of tickling is full of mysteries, but there are a few humorous theories. Some scientists suggest that tickling may have evolved as a defense mechanism. For example, the areas that are most ticklish, such as the neck, ribs and armpits, are also some of the most vulnerable parts of the body. Tickling can be a way to teach young animals to protect these sensitive areas. Another theory suggests that tickling helps strengthen social bonds. The laughter and play associated with tickling can promote social interaction and bonding between family and friends.

The neuroscience of tickling: what's going on in the brain?

Neuroscientists have recently tracked the specific areas of the brain involved in tickling sessions. Research in rats shows that the same somatosensory circuits involved in play behavior also fire when the subject is tickled. Other areas of the brain that become active when tickled include those responsible for touch processing associated with the fight-or-flight response, vocalization, and emotional areas such as the amygdala and anterior cingulate cortex.

Dr. Sara Proels, Ph.D., of the Bernstein Center for Computational Neuroscience in Berlin, Germany, studied the human response to tickling in her neuroscience research. "It has some exciting features," Proels explains. Although there are still significant mysteries and unknowns, scientists like her have come up with interesting conclusions and explanations about why we are so ticklish and what happens during a tickling session.

Why can't we tickle ourselves?

A unique aspect of tickling is our inability to tickle ourselves. The brain predicts self-generated movements that seem to blunt the tickle response. This prediction mechanism allows the distinction between self-initiated actions and external stimuli, which is important for survival.

The evolutionary role of tickling: a personal opinion

From my point of view, tickling is not just a form of play. It is a unique combination of sensory processing and emotional response that may have played a crucial role in human evolution. A tickle can promote the development of social bonds and teach young animals to protect their most vulnerable places. Whether as a defense mechanism or a means of bonding, tickling remains an intriguing and somewhat mysterious aspect of human behavior.

The neuroscience of tickling opens a window into our complex sensory and emotional world. While there are still many unanswered questions, understanding why we're ticklish offers insight into the complex workings of the brain and the evolutionary traits that have shaped human interaction.

Delving deeper into the brain's response to tickling, researchers continue to uncover the nuances of this seemingly simple, yet highly complex behavior. The next time you feel that familiar squirm or hear someone giggle from being tickled, remember that there's more going on than meets the eye.

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