As part of his research, he is heavily involved in studying a new field, called optogenetics. In its simplest description, optogenetics allows scientists to turn on and turn off neurons using light. And they are figuring out how to do this in the brain, which means a potential cure for Parkinson's and depression and who knows what else.
Wired magazine ran a fascinating story on this recently - Powered by Photons. This article describes the process of getting a mouse's brain to react to light in a way that caused it to engage in a specific behavior:
In the summer of 2007, a team of Stanford graduate students dropped a mouse into a plastic basin. The mouse sniffed the floor curiously. It didn’t seem to care that a fiber-optic cable was threaded through its skull. Nor did it seem to mind that the right half of its motor cortex had been reprogrammed.
One of the students flipped a switch and intense blue light shone through the cable into the mouse’s brain, illuminating it with an eerie glow. Instantly, the mouse began running in counterclockwise circles as though hell-bent on winning a murine Olympics.
Then the light went off, and the mouse stopped. Sniffed. Stood up on its hind legs and looked directly at the students as if to ask, “Why the hell did I just do that?” And the students whooped and cheered like this was the most important thing they’d ever seen.
Because it was the most important thing they’d ever seen. They’d shown that a beam of light could control brain activity with great precision. The mouse didn’t lose its memory, have a seizure, or die. It ran in a circle. Specifically, a counterclockwise circle.
The article goes on to explain this process in detail and describes how it could be used someday to completely correct problems with the brain.
It's a well-written article, one well worth reading. And you should remember this word - optogenetics. It could have an important effect on your life one day.