Can tickling kill?
It is likely that at some point in your life you have been tickled, repeatedly touched in a way that causes smiles, laughter and involuntary movements. Tickling can occur in many places on the body, but the most common are the rib cage, armpit, and the sole of the foot. Tickling often occurs in the context of intimate relationships: parents tickle their babies and young children; siblings, romantic partners, and close friends sometimes tickle each other. Some people seem to be more ticklish than others.
If done gently, they are pleasant, but when they last too long or their intensity is excessive, they can be much more than annoying; so, tickling is as much a classic of romp and pickup as it is an element of torture. In reality, tickling is a self-defense reaction of the body, that is, a primitive instinct that forces the body to react to dangerous situations, such as preventing the poisonous attacks of a spider or scorpion that walks on the skin. This is why we cannot tickle ourselves: if our brain did not have the ability to keep track of our body movements and the sensations they cause, we would constantly feel as if we were being brushed and poked, and it would be difficult devote our attention to something else. But it is not like that: your brain knows that the fingers that prick you in the rib cage are your own fingers, so it marks the sensory response.
The signal produced by the stimulation of touch receptors in the dermis travels to two brain regions: the somatosensory cortex, which processes touch; and the anterior cingulate cortex, which handles pleasant information. The neurons in these areas trigger an immediate response in the form of sudden body movements and a nervous laugh that is difficult to control.