0
By Sharon Thompson
National Geographic Kids Magazine
February 04, 2004
Scientists at University College, London, England, (see map) now know why you can't tickle yourself.
Your brain knows ahead of time to expect the sensation and ignores the signal from your skin.
When someone else tickles you, however, your brain is taken by surprise and can't shut off the skin's message.
When study participants brushed their own palms with a piece of foam, an area at the back of the brain, called the cerebellum, barely lit up on a brain scan. But when researchers brushed the participants' palms with the foam, the cerebellum lit up brightly.
So you can't fool your brain, but other people can!
Source: NationalGeographic.com
.. 
