The “wiring diagram” created by the FlyWire project reveals each of the 139,255 neurons in the fruit fly brain and the 50 million connections between them, a breakthrough that will revolutionize the field of neuroscience and pave the way for unprecedented insights into how Brain for behavior.
While the human brain contains about a million times more neurons than a fly’s brain, scientists say this brings us closer to understanding our own minds.
Although the adult fruit fly brain is less than a millimeter wide, it is still an extremely complex structure to study. It has taken years for scientists to map the meanderings of all the neurons and connections assembled within the brain.
In the process, scientists classified more than 8,400 different cell types, equivalent to the first complete list of parts needed to build a fly’s brain.
“You might wonder why we should care about the fruit fly brain,” said Sebastian Seung, a professor of computer science and neuroscience at Princeton University and co-leader of the FlyWire project. “My simple answer is that if we could truly understand how any brain works, it would certainly tell us something about all brains.”
The complex tangle of neurons, which if unraveled would extend 150 metres, was mapped through a painstaking process that began by slicing the brain of a female fruit fly into 7,000 thin slices. Each section was imaged in an electron microscope to reveal structures as small as four millionths of a millimeter across.
The team then turned to artificial intelligence to analyze millions of images and trace the path of every neuron and synaptic connection throughout the tiny organ.
Because the AI made so many mistakes, a global army of scientists and volunteers was recruited to help correct the errors and finish the map.
Scientists have discovered “effector” neurons that appear to combine different types of information, and “announcers” that may send signals to coordinate activity across different neural circuits.
A specific neural circuit has also been observed that, when triggered, causes fruit flies to stop dead in their tracks while walking.
The scientists used a “wiring diagram” to build a computer simulation of part of the fly’s brain. Experiments with simulations led them to identify the neural circuits used to process taste, suggesting that future simulations could shed more light on how animal behavior emerges through brain wiring.
Details of the project, which involved 287 researchers from more than 76 laboratories around the world, including researchers from Canada, Germany, the MRC Laboratory for Molecular Biology and the University of Cambridge in the United Kingdom, were published in nine papers in the journal Nature.
In an accompanying article, Dr. Anita Devineni, a neuroscientist at Emory University in Atlanta, called the “wiring diagram” a “landmark achievement.”
The team has now already begun work on producing a complete ‘wiring diagram’ of the mouse brain, which they hope to complete within five to ten years. But replicating this feat for an entire human brain, with its 86 billion neurons and trillions of connections, is still beyond practical reach with today’s technology.
Source: The Guardian
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2024-10-04 15:01:26
