“In one challenge, the youths maneuver through a maze of corridors, searching for bright green dollar signs. Another tests their ability to recognize an error on the screen. All the while, the scanner is photographing “slices” of their brains. The ultimate reward is far more than a game.” Researchers hope advances in brain imagery — and computers that can crunch a ton of data — will help them come up with a cause and a cure for obsessive compulsive disorder.