Scientists have created a new way to make a human brain transparent, allowing them to take deep three-dimensional tours and view large networks of neurons with unprecedented ease and accuracy.

The technology also opens up new research avenues for old brains that were saved from patients and healthy donors. The new discovery, published online Wednesday by the journal Nature, is being heralded by scientists as "transformative" and a major breakthrough. The process involves washing away the fat that normally hinders the view of cells and replacing it with a see-through gel which keeps everything intact while scientists analyze the brain.

The new methodology is called CLARITY and was devised by Karl Deisseroth and his team at Stanford University in California. "You can get right down to the fine structure of the system while not losing the big picture," says Deisseroth, who adds that his group is in the process of rendering an entire human brain transparent.

"This feat of chemical engineering promises to transform the way we study the brain's anatomy and how disease changes it," said Dr. Thomas R. Insel, director of the National Institute of Mental Health, which funded the research conducted at Stanford University. Existing technology already allows scientists to see neurons and their connections in microscopic detail; however that is only across tiny slivers of tissue. Researchers must reconstruct three-dimensional data from images of these thin slices.

Researchers say CLARITY will allow for a better understanding of the pathways underlying both normal mental function and neurological illnesses from autism to Alzheimer's. In fact, the first human brain the scientists clarified came from someone with autism.

The announcement comes just a week after President Barack Obama announced a $100 million initiative to examine the mysteries of the brain.