"Brain imaging research techniques such as PET scans (positron emission tomography) and fMRI (functional magnetic resonance imaging) clearly show that the vast majority of the brain does not lie fallow. Indeed, although certain minor functions may use only a small part of the brain at one time, any sufficiently complex set of activities or thought patterns will indeed use many parts of the brain. Just as people don't use all of their muscle groups at one time, they also don't use all of their brain at once. For any given activity, such as eating, watching television, making love, or reading Skeptical Inquirer, you may use a few specific parts of your brain. Over the course of a whole day, however, just about all of the brain is used at one time or another."

http://www.csicop.org/si/9903/ten-percent-myth.html
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The lover of inquiry must follow his beloved wherever it may lead him.
-Socrates