If you want to go from scrawny to brawny in 30 days, there is no shortage of miracle shape-up programs. But as impressive as beefy pecs and triceps may look, they won't help you cite the evidence for Einstein's special theory of relativity, rattle off pi to the 20th decimal place, or liberate yourself from the mass delusion that a penny dropped from the Empire State Building will gather enough speed to kill a hapless pedestrian. We at PopSci believe the body part most worth stretching and toning—not to mention showing off—is the brain. You need to ensure that yours is flexible enough for creative problem solving, strong enough to run the occasional intellectual mini-marathon, and most of all, free of pseudoscientific flab.
You say the brain isn't really a muscle? Irrelevant. Recent studies indicate that it can bulk up: The hippocampus, a brain region responsible for thought and memory, produces new cells throughout a person's life, and some neuroscientists believe other parts of the brain also regenerate. The trick to keeping those new neurons? Use 'em or lose 'em. So take our scientific-aptitude quiz, learn the mental muscle groups, and get pumping.