Do humans use only 10 percent of their brains? In the new movie "Lucy," starring Scarlett Johansson and Morgan Freeman, a mysterious drug allows Lucy to use 100 percent of her brain's capacity instead of the typical 10 percent (according to the film's sci-fi logic), giving her access to a range of amazing powers. In this latest installment of Emory Looks at Hollywood, Emory University neurologist Krish Sathian debunks the lingering yet popular myth that people use only 10 percent of their brains.