Karl Deisseroth

  Two or three years ago, Emory neurologist Helen Mayberg, whose experiments using deep-brain stimulation for depression I check in on now and then, told me that Karl Deisseroth's work using light to fiddle with brain circuits had huge potential both as a replacement for DBS and for much else. As Lizzie Buchen ably reports in Nature, that potential is now being realized. This is a very slick tool that seems almost too far out to actually work. It lets you use light to turn brain circuits on and off at will, and with great precision. It's not simple to construct. But once constructed, it…