Is That True That

Is it true that humans only use 10% of their brains?

I just want to expand a little on what Joel Lewenstein wrote.What would it even mean to "use" 10% of your brain? Only 10% of your neurons are necessary for your normal functioning? Are you willing to sacrifice 90% of your brain to see if that's true?One of the methods neuroscientists use to study brain function is to look at patients with brain lesions and show how those affect cognition and behavior. It's precisely what I do:http://www.berkeley.edu/news/med...http://blog.ketyov.com/2010/10/v...http://blog.ketyov.com/2010/11/v...We know very well that a lesion to most any given brain region has a behavioral effect.While that's a practical example, from even a theoretical standpoint, not doing something is still an active state in the central nervous system. For example, the photoreceptors of your eye are always firing action potentials and releasing neurostransmitter in the absence of light (this is called the "dark current"). When light stimulates those cells, they stop firing action potentials and releasing transmitter. Thus, the act of not doing something is the actual signal. (From a signal standpoint, this is really quite amazing and makes a lot of sense: a signal is more clean if you shut a noisy system off and use that to communicate digitally than it is to try and boost a signal above background noise).So in the brain, even regions that appear to be not doing anything may actually be doing some communication/information transfer/processing/whatever.EDIT: Also, neurons follow a "fire together, wire together" and "use it or lose it" type of pattern. Neurons that communicate with one another a lot (that is, fire together) are less likely to undergo programmed cell death (apoptosis) through a complicated biochemical reinforcement. In contrast, if a lonely neuron isn't really doing much, then it is "pruned", that is, it isn't receiving a biochemical signal telling it to not commit cellular suicide, so it breaks down.So even if we were only using 10% of our brains in some hypothetical world, the other, useless 90% would start to go away!