In images that one researcher likens to a "Google Map" for brains, a deep dive into a mouse's gray matter shows how its smallest parts communicate, driving the much larger machine of its body. Explore more secrets of the brain online in National Geographic magazine: ngm.nationalgeographic.com/2014/02/brain/zimmer-text PRODUCER: Shannon Sanders ANIMATIONS AND 3-D RENDERINGS: Jason Treat, Kurt Mutchler, Bryan Christie, Joe Lertola, and the Harvard SEAS Connectome Group: Jeff Lichtman, Seymour Knowles-Barley, Narayanan Kasthuri, Verena Kaynig-Fittkau, Mike Roberts, Amelio Vázquez-Reina, Bjoern Andres, Daniel Berger, Thouis R. Jones, Eric Miller, Hanspeter Pfister, Sebastian Seung (MIT), Richard Schalek, Kenneth Hayworth, and Juan-Carlos Tapia