Scientists mapped every neuron of an adult animal's brain for the first time

Brains are bewilderingly complicated systems of connections between neurons. Mapping those connections is an important step in understanding how brains work. Scientists have recently completed the most ambitious effort yet to construct such a map: a complete document of every neuron and every connection in the brain of an adult fruit fly. The research represents the first such map for an animal that can walk and see, and the first complete map of the brain of an adult animal. It traces each and every one of the 139,255 neurons in the brain of Drosophila melanogaster, along with the 50 million connections between them, and is by far the largest and most detailed ever produced.