What if neuroscientists could look inside the human brain and watch individual brain cells send signals to one another? What if they could then control these brain cells to direct thoughts and actions? This may sound like science fiction, but it's actually a scientific revolution called optogenetics. Neuroscientists would like to use this new technology on human brains to uncover secrets about how the brain processes information and drives human behavior. Doctors hope to use optogenetics to restore sight and to treat Alzheimer's disease, Parkinson's disease, depression, and other debilitating or deadly health problems. Discover how the innovative work of leaders in the field is poised to radically transform science, medicine, and human health.