Tickling: self vs. non-self :)

Jay Leno might think that its really ridiculous for a John Hopkins team to study why one can not tickle oneself, while there are bigger health reltaed issues facing man-kind. But this one got me thinking.....after all, its tactile impulse that the neurons receive. How does the brain figure out that it is self tickling and thus there is no need to jump etc ;). Our brain is smart, wired so, that we don't jump each time there is a self tactile pressure. When one tries to self tickle, the brain knows where and how the tactile impulse is moving, because its your own fingers generating that impulse. But for non-self tickling, its always a suspense! The brain can not track whats going to happen next, an alarm is set off and there you are, tickle tickle, giggle giggle :).

Apparently its our cerebellum that can distinguisgh between expected (self) and un-expected sensations (Original research article). Upon self-tickling, the cerebellum can signal somatosensory cortex of the brain on what sensation to expect, and this dampens the tickling sensation. Also, to quote from Robert Provine's article:

Tickle, an ancient laughter stimulus, is a means of communication between preverbal infants and mothers, and between friends, family, and lovers. Because you cannot tickle yourself, tickle involves a neurological self/nonself discrimination, providing the most primitive social scenario.

Its interesting how our brain is wired to distinguish between self and non-self: and isn't that the first line of defense.