Stanford University researchers developed a process to make a mouse brain totally transparent. The brain has to be, er, removed from the mouse first but it's still an amazing process that enables scientists to see the entire brain in great detail, without chopping it up. Brilliant bioengineer, Karl Deisseroth, a pioneer in the field of optogenetics, postdoc Kwanghun Chung, and their colleagues have used the same technique, called CLARITY, to make fish and, yes, bits of human brains transparent as well. The process involves replacing the fatty molecules, called lipids, with a hydrogel. As a result, the brain can be studied with visible light and chemical markers with unprecedented clarity and resolution. Check out the stunning fly-through of the rodent's brain above.