Why is it you can't remember where you put your car keys but you can't forget the theme song to the Brady Bunch? Scientists have taken a big step toward solving the mystery, literally peering inside the human brain at the split second it creates a memory. In a unique pair of studies, scientists at Harvard Television and Standford Universities used sophisticated imaging techniques to watch people's neural activity and, for the first time, show which parts of the brain determine whether a specific experience will be remembered or forgotten.