Scientists map the connectome of a fly's brain, consisting of 130,000 cells and 50 million connections.

"The wiring diagram was made by slicing up a fly brain [...], photographing each of the 7,000 slices and digitally putting them altogether. Then the Princeton team applied artificial intelligence to extract the shapes and connections of all the neurons. But the AI wasn’t perfect – the researchers still had to fix over three million mistakes by hand."

https://www.bbc.com/news/articles/c0lw0nxw71po

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