Mapping brain connections is tricky -- chemicals can destroy the very structures you're trying to map, and an electron microscope can only tell you so much. MIT researchers aren't daunted, however. They've developeda new 3D imaging technique that lets you map the brain at multiple scales, including at resolutions that aren't practical with light-based microscopes. The new approach expands on a conventional chemical-based method of preserving brain tissue samples. If you flood the tissue with acrylamide polymers, you form a super-dense gel that lets you expand the sample up to 5 times its original size without hurting its structure, making it easier to study minute details.

 Numerous microscopes can study neural structures like synapses at resolutions as fine as 60 nanometers, which beats the 200nm you might get through conventional light microscopes.

Moreover, you can reverse and repeat the process "many" times. If you need a broader view, you don't need to collect a new sample. That makes it considerably easier to trace brain connections, as you aren't locked into viewing one scale the entire time.
MIT is currently focused on speeding up the imaging process, so this technique won't be in use for a while. However, the team's Kwanghun Chung notes that the technique is both "really simple" and uses standard molecular markers -- it'll be easy to adopt when it's ready. Assuming everything goes smoothly, scientists could have a deeper understanding of the brain that might lead to more effective treatments for diseases.