See-Through Brain Tissue Promises to Advance Autism Research

In a dramatic breakthrough, researchers have developed a method for rendering brain tissue transparent. They then used fluorescent chemicals to highlight three-dimensional networks of brain cells and fibers to study their connections.

“This feat of chemical engineering promises to transform the way we study the brain’s anatomy and how disease changes it,” said Tom Insel, M.D., director of the National Institute of Mental Health.

Thanks to post-mortem donations, Autism Speaks Autism Tissue Program was able to provide the Stanford University researchers with the brain tissue of an individual affected by autism. Using it, they traced the paths of individual nerve cells and their connections.

In addition, the Stanford University research team rendered an entire mouse brain transparent. By highlighting its nerve connections, they created a three-dimensional “tour” of an intact brain. (Watch embedded video above.)

Next the researchers hope to accomplish the same feat with an intact human brain. They call their technique CLARITY, for “Clear Lipid-exchanged Anatomically Rigid Imaging/immunostaining-compatible Tissue Hydrogel.” In essence, it replaces the brain’s light-blocking fat with a transparent hydrogel.

“CLARITY has the potential to unmask fine details of brains from people with brain disorders without losing larger-scale circuit perspective,” said National Institute of Health Director Francis Collins, M.D., Ph.D.

The researchers also demonstrated that immunological and genetic tests can be performed repeatedly on the same stained brain tissue. This is crucial for autism and other brain research that depends on scarce postmortem donations.

“The history of neuroscience discovery has been paved, in large part, by innovations in the preparation of brain tissue for research,” said Rob Ring, Ph.D., Autism Speaks vice president of translational research. “However, the ability of CLARITY, and innovations like it, to create new knowledge on the origins of disease will remain dependent on the availability of quality brain tissue from affected individuals.” Dr. Ring oversees Autism Speaks ATP program.

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