In early October, scientists revealed something spectacular -- a complete map of a fruit fly's brain. Roughly the size of a grain of salt, a fly's brain has 140,000 neurons connected by almost 500 feet of biological wiring. The map showed myriad types of cells and how they're connected. It promises to help us gain a better understanding of how brains work. Scientists are rejoicing.
It was a huge achievement, but it also showed how hard it will be to take the next big step forward. Hundreds of scientists spent a decade carving the brain into tiny slices that could be photographed at high resolution, reassembling those millions of images into a unified picture, then analyzing it all with human experts and artificial intelligence software. The previous high-water mark for the field, a whole brain map -- known as a connectome -- of a worm with 302 neurons, came in the 1980s. Getting to the fly's 140,000 neurons required a host of breakthroughs.