Scientists map part of a mouse's brain that's so complex it looks like a galaxy

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, the researchers identified those neurons and traced how they communicated via branch-like fibers through a surprising 500 million junctions called synapses.

The massive dataset, published Wednesday by the journal Nature, 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.