Thanks to a mouse watching clips from The Matrix, scientists have created the largest functional map of a brain to date—a diagram of the wiring connecting 84,000 neurons as they fire off messages. Using a piece of that mouse’s brain about the size of a poppy seed, a global team of more than 150 researchers identified those neurons and traced how they communicated via branch-like fibers through a surprising 500 million junctions called synapses. The massive dataset marks a step toward unraveling the mystery of how our brains work. The data, assembled in a 3D reconstruction colored to delineate different brain circuitry, is open to scientists worldwide for additional research—and for the simply curious to take a peek.
