Even in our most thoughtless moments, our brains are hard at work. They are incredible triumphs of evolution and warrant endless fascination and reverence. "The brain is essentially who you are, so understanding what it is, how it works, I think, should be important to everybody," says Ellen Carpenter, professor of psychiatry and biobehavioral science at the UCLA School of Medicine. It's also a subject that can get downright trippy. Here, with Carpenter's help, are some wild facts about your most important organ.