Those few early scientists who were bold enough to cut open cadavers, from the Roman Galen to the Renaissance-era Vesalius, advanced the understanding of anatomy dramatically but didn't glean much information when it came to the brain. To the naked eye, the lumps of gray matter revealed few secrets. But the 19th century Italian scientist Camillo Golgi had the advantages of microscopes, and the cell staining technique he went on to invent opened the way for modern neuroscience.

By treating slices of brain tissue with a chemical solution, Golgi revealed the delicate structures of individual brain cells, from dendrites to axons. The drawings he created from his observations helped establish a truth of brain science--that the brain can be understood on its most basic level as an organized collection of individual neurons. This drawing of a dog's olfactory bulb dates from 1875.