We met following a weekend that Beth was away with a group of couples and had had enough with 'the single life' and decided she would go on a date with 'the next half decent guy' that sent her a message on RSVP.After more than a century of study, neuroscientists have yet to unlock the secrets of how people learn and form thoughts.Some researchers think having a “connectome,” or brain wiring diagram showing how the billions of neurons there interface, will help solve the mystery.
They painstakingly add series of images together to eventually render a three-dimensional picture of brain circuitry.
A chemical method that makes brain tissue transparent could revolutionize this process by enabling researchers to see inside the brain without carving it up.
A research team led by Karl Deisseroth of Stanford University developed the patented Clarity method, for converting brain tissue into a clear hydrogel (Nature, DOI: 10.1038/nature12107).
Deisseroth’s research team infuses brain tissue with acrylamide monomers, formaldehyde, and a heat- activated initiator compound for a few days.
They next warm the refrigerated tissue to initiate polymerization, forming a hydrogel mesh that anchors structures such as neurons in place.
An electric field and negatively charged detergent are then used to extract the lipids that make the tissue visually impenetrable.
That final step, dubbed “electrophoretic tissue clearing” by the team, was the most challenging to develop, says Kwanghun Chung, a Stanford postdoctoral researcher and lead author of the report.
“We melted and burned hundreds of mouse brains before we figured out the optimum conditions, such as voltage level.” Eventually, the Stanford team immunostained blocks of both a mouse brain and a brain from a deceased autistic patient with fluorescent antibodies of different colors to generate 3-D rainbow maps of brain features.
But just as important as Clarity’s ability to make tis- sue transparent is its ability to make tissue somewhat permeable, comments Qingming Luo, a biomedical engineer and vice president of China’s Huazhong University of Science & Technology.