Scientists from Google and Virginia’s Janelia Research Campus have released the largest high-resolution image of animal brain connections to date, and the 3D model they shared is known to track 20 million synapses in about 25,000 neurons in the brain that connect fruit flies,media reported.
The model is a milestone in the field of connectivity, using detailed imaging techniques to map the physical path of the brain. The map, known as the “connectome,” covers about a third of the fruit fly’s brain. So far, only one creature, the brain of the beautiful hidden nematode, has been described in such detail.
In the scientific community, the reputation of connectivity is mixed. Proponents argue that it helps to link physical parts of the brain to specific behaviors, a key goal of neuroscience. But critics say it hasn’t brought any major breakthroughs, pointing out that the hard work of mapping neurons is a drain on resources that could have been used better.
“Rebuilding is undoubtedly a technical miracle,” Mark Humphries, a neuroscientist at the University of Nottingham, told The Verge.com. But he points out that this is also a major resource that other scientists are now using, and that it does not answer any pressing scientific questions in itself, but it may lead to some interesting mysteries.
This 3D diagram, produced by the FlyEM team at Google and Janelia, is undoubtedly a technological achievement, the product of automation and a lot of manual labor.
It is understood that the first step in making this map is to cut parts of the fruit fly’s brain into 20 micron-thick pieces, about a third the width of human hair. Fruit flies are a common object in connected studies because their brains are relatively simple, the size of poppies, but can exhibit complex behaviors such as courtship dancing. These brain slices are then bombarded with electron streams that scan electron microscopes to image them. The resulting data consists of about 50 trillion 3D pixels, which are processed by algorithms that track each cell’s path.
Despite its powerful algorithmic capabilities, Google still needs a lot of manpower to check the software’s work. The company says Janelia’s scientists spent two years and hundreds of thousands of hours “proofing” 3D maps, while also using virtual reality helmets and custom 3D editing software to verify the path of the 20 million chemical synapses.
Even so, the resulting map covers only a part of the fruit fly’s brain, the half-brain. Fruit flies have a total of 100,000 neurons in the brain, compared with about 86 billion in the human brain. This suggests that people are still a long way from building a complete neural pathway connection.
Joshua Vogelstein is a biomedical engineer and co-founder of the Open Connectome project. Vogelstein says the data provided by these projects will finally begin to bear fruit over the next decade.