scientific breakthrough. it's called clarity, and this picture shows what happens. on the left, a completely in tact brain from a house. on the right, a brain that is completely transparent. it's there, but almost invisible. after being bathed in a solution invented by the doctor and his team. >> it was the inability to see anything at all that was the most exciting thing. then that moment was really, i think, a transformative moment. >> reporter: later, you get these images through the use of fluorescents. in the past, this opaque organ had to be sliced open to get a view. >> what we worked on with this technology is a way to see through the brain without taking it apart. >> reporter: with the brain in tact, scientists can study it more thoroughly. >> to look at all those pathways that we have speculated on for