Scientists map portion of mouse’s brain
WASHINGTON — 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.