Researchers at Harvard University and Google have co-created the largest synaptic-resolution, 3D reconstruction of a piece of human brain to date.The image shows, in vivid detail, each cell and its web of neural connections in a piece of human temporal cortex about half the size of a rice grain.The achievement, published in the journal Science, is the latest in a nearly 10-year collaboration with scientists at Google Research, who combine Harvard researcher Jeff Lichtman’s electron microscopy imaging with AI algorithms to colour-code and reconstruct the extremely complex wiring of mammal brains.The paper’s three co-first authors are former Harvard postdoctoral researcher Alexander Shapson-Coe; Michał Januszewski of Google Research, and Harvard postdoctoral researcher Daniel Berger.The collaboration’s ultimate goal, supported by the National Institutes of Health BRAIN Initiative, is to create a high-resolution map of a whole mouse brain’s neural wiring, which would entail about 1,000 times the amount of data they just produced from the 1-cubic-millimetre fragment of human cortex.Lichtman, the Jeremy R. Knowles Professor of Molecular and Cellular Biology and newly appointed dean of science at Harvard, saod@“The word ‘fragment’ is ironic.“A terabyte is, for most people, gigantic, yet a fragment of a human brain – just a miniscule, teeny-weeny little bit of human brain – is still thousands of terabytes.”The latest map in Science contains never-before-seen details of brain structure, including a rare but powerful set of axons connected by up to 50 synapses.The team also noted oddities in the tissue, such as a small number of axons that formed extensive whorls.Since their sample was taken from a patient with epilepsy, they’re unsure if such unusual formations are pathological or simply rare.Lichtman’s field is “connectomics,” which, analogous to genomics, seeks to create comprehensive catalogues of brain structure, down to individual cells and wiring.Such completed maps would light the way toward new insights into brain function and disease, about which scientists still know very little.Google’s state-of-the-art AI algorithms allow for reconstruction and mapping of brain tissue in three dimensions.The team has also developed a suite of publicly available tools researchers can use to examine and annotate the connectome.Google Research collaborator, Viren Jain, said: “Given the enormous investment put into this project, it was important to present the results in a way that anybody else can now go and benefit from them.”Next the team will tackle the mouse hippocampal formation, which is important to neuroscience for its role in memory and neurological disease.Image: Google Research and Lichtman Lab
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