For several years, an international consortium of researchers, FlyWire, has been working on ultra-precise mapping of the brain of a fruit fly. No bigger than a grain of sand, the brain of a Drosophila melanogaster Adults contain 139,255 neurons and 54.5 million synapses. The feat of this investigation, which led to the publication of a dozen articles on October 2, in Natureis to identify the connections and networks that constitute what they called the “connectome.”
First it was necessary to cut this “grain of sand” into seven thousand slices, examine the first ones by hand before asking an artificial intelligence to continue the work and then make human corrections. Thus, teams from the universities of Princeton (New Jersey) and Cambridge (Massachusetts) have annotated classes of neurons and cell types according to their connections and functions. They identified more than eight thousand types of cells. An unexpected result.
The FlyWire consortium, supported in particular by American research institutes, is also funded by Google and Amazon, whose teams were called upon to carry out this titanic work. The previous precision record for neuronal wiring in the brain of a fly was about twenty thousand neurons and fourteen million synapses in a patch of gray matter.
All of this work allows us to study how brain functions are determined by the structure of brain circuits, which constitutes a valuable resource for neuroscience research. Because the fly brain is considered an interesting model, while this small animal is capable of sophisticated behaviors such as walking and flying, learning, memory, navigation and even social interactions.
Advancing research
This dive into the brain’s electrical cabinet revealed its share of surprises in the tangle of connections. For example, it has been discovered that neurons involved in wiring one sense, such as vision, are also wired to receive signals from other circuits, such as hearing or touch.
The study of this connectome should help to understand the consequences that dysfunctions in brain circuits can have. A better understanding of these mechanisms could also advance research into the treatment of neurological disorders.
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