Karl Deisseroth, whose work this is, has managed to preserve the intricate, intertwining mesh of connections in the brain of a rat while eliminating all the surrounding tissue that would ordinarily obstruct our view of those cells. With powerful microscopes it becomes possible to tour the otherwise impenetrable spaces of the brain, sussing out connections and looking at differences between normal and diseased brains. In one case, they discovered for the first time some unusual structures in a portion of a brain of a young boy with autism. These kinds of discoveries could help guide the work of scientists developing new therapies for brain diseases.
Deisseroth calls his technique CLARITY, and it can apparently be used to see through other organs of the body. His CIRM-funded work focuses on using light to guide embryonic stem cells to develop into therapeutically useful cell types.