I learned that scientists could control neurons with light, I definitely did not keep my cool. My response was something like, “Holy shit, I had no idea you could do that!”—perhaps not the best thing to say when you’re trying to convince a neuroscience professor to hire you as an undergraduate researcher. I did not get hired.
That was 2008, when the groundbreaking new technique of optogenetics was just bursting into neuroscience. Optogenetics is matter of putting light-sensitive proteins, called opsins, in specific neurons using genetic tools. (The name is quite logical.) The resulting possibilities still have a shade of science fiction: A flash of blue light to a certain bundle of neurons can turn an ordinary mouse into a seething ball of aggression . Or implant false memories . Or let deaf mice hear again . Hundreds, if not thousands, of labs now use this technique.