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 developed a 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.