Scientists turn brain transparent in order to better map it

Though mapping the brain with modern-day technology isn’t strictly impossible, it takes quite a bit of time and effort. Similar to creating a large panoramic shot of the night sky, modern-day methods used to chart the brain consist of mapping small areas of the organ separate from one another, then connecting the resulting images together. Considering the brain is a three-dimensional object and quite complex, the method of piecing together tiny, completed maps can result in significant errors. Now, Karl Deisseroth and his team at Stanford University in California have created a method to make whole brains transparent, allowing researchers to get a much clearer view of the organ.

Called Clarity, the technique uses sodium dodecyl sulfate (SDS), an organic compound found in standard detergent, to turn the braintransparent. The SDS removes lipids that prevent the passage of light. This method has been used before — and to some success. However, most techniques that attempt to remove lipids also dissolve proteins and damage the tissue in such a way where it’s difficult to discern one neuron from another, resulting in about 41% protein loss.

The Stanford team solved this issue by adding acrylamide to the mix, which is a chemical compound that when heated, forms something of a “mesh” that protects and contains the tissue. Using this method when removing lipids, only around 8% of the proteins were lost.

The tissue that results from the Clarity method ends up harder and more stable than tissue that didn’t go through the treatment. Considering it can change preexisting tissue into something more stable, it is theorized that old specimens can be somewhat revitalized and made reusable for study. Deisseroth feels that since the specimens can be made sturdier and reusable, scientists could theoretically create something of a brain library. This would provide researchers with specimens they can check out to study, and without the fear of damaging the specimen as much as it could be if it didn’t go through with the Clarity treatment.

The Clarity technique is relatively new, so further thorough testing is needed, as it is possible that the SDS application and subsequent lipid removal damage the structure of the brain tissue. So far, however, the method looks promising.