Ultrathin slices of mouse brains offer a mesmerizing look at how brain cells communicate at the tiniest scale. This research may offer clues about how the dance of our own synapses guides and animates us. Explore more secrets of the brain online in National Geographic magazine: http://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