10% vs 3%

General Questions
#1

At one point in tonight’s episode of the Simpsons, Bart says something to the effect that the drug he’s taking (Focusyn) will allow him to use 10% of his brain, like most people do.

I’ve heard or read a while back that Einstein used 10% of his brain capacity, whereas we mere mortals used only 3%. Given the Simpsons’ writing team usual attention to facts and details, it got me wondering… What’s the Straight Dope?

#2

http://www.urbanlegends.com/science/10_percent_of_brain.html

#3

I’ve read the whole “humans only use 10% of their brain power” thing is a misconception. It came from the fact that only about 10% of the mass of a human brain is neurons, while the other 90% is fat and water, ergo you only use 10% of your brain’s mass or something akin to that. I don’t think there’s any way one could calculate the potential of the human brain anyway.

#4

http://www.straightdope.com/classics/a3_028.html

#5

I loved that,Focusyn.How relevant.