Think a census of humans is hard? Try counting their brain cells!

In 2013, the U.S. government began investing $100 million to decipher human brain anatomy in a large collaborative project called the BRAIN Initiative. Researchers built tools and set standards for describing all the cells in the brain. On October 7, 2021 the initiative reached a major milestone, publishing a comprehensive census of cell types in the mouse, monkey, and human primary motor cortex.