A complete wiring map of the male fruit fly’s nervous system

Researchers at HHMI Janelia, Google Research, and partner labs have released a complete connectome: a wiring diagram of every nerve cell and its links in one adult male fruit fly’s central nervous system. The map covers both the brain and ventral nerve cord, the insect’s rough equivalent of a spinal cord, tying sensation in the head to movements in the body in a single dataset. It records 166,691 neurons and about 125 million synapses, making it the largest brain map yet by neuron count. It will not explain thought or behavior on its own, but it gives scientists a shared reference for tracing circuits, comparing male and female flies, and improving the tools needed for far harder maps in fish, mice, and eventually humans.