Today, an international A team of researchers shared an extraordinarily detailed atlas of human brain cells, mapping their astonishing diversity of neurons. The atlas was published as part of a massive package of 21 articles in the journal. Science, each of which takes complementary approaches to the same general questions: What types of cells exist in the brain? And what differentiates the human brain from that of other animals?
With hundreds of billions of intertwined cells, mapping the entire brain is like trying to map every star in the Milky Way. (The inner workings of each cell are miniworlds unto themselves.) But just as the best telescopes clarify the universe for astronomers, the analytical tools presented here give neuroscientists “unprecedented resolution when looking at brain cells, which will open up new windows for understanding. brain function,” says Andrea Beckel-Mitchener, deputy director of the BRAIN Initiative at the U.S. National Institutes of Health, which funded the cell atlas projects.
With a complete map of cell types, it is within our reach to understand how neurons work and how brain disorders cause them to malfunction. “This is a first step toward defining the cellular complexity of the brain,” said Bing Ren, professor of cellular and molecular medicine at the University of California, San Diego and principal investigator of the atlas project. “The results have been nothing short of surprising.”
This is not the first atlas of brain cells, nor will it be the last. But it’s incredibly detailed. The collection of 21 studies reports findings from the BRAIN Initiative’s latest five-year funding program, BICCN (BRAIN Initiative Cellular Census Network). The NIH allocated $100 million to this initiative, with the goal of cataloging brain cell types in greater depth than ever before. “The only other large-scale biological problem we’ve thought of of this magnitude is the Human Genome Project,” says Beckel-Mitchener. “The cell atlas project is the largest scientific team effort in neuroscience.”
Historically, it has been nearly impossible to understand the complexity of the human brain. With so many interconnected pieces, “it’s really not one organ, but like a thousand organs,” says Ed Lein, a senior investigator at the Allen Institute for Brain Science who helped lead the atlas project.
“Before this data set, it was just a hypothesis “That the brain was really complicated,” adds Amy Bernard, director of biological sciences at the Kavli Foundation, who was not involved in this project. “Now we can see the cellular diversity and understand the problem.”
Neuroscientists often think of the brain in terms of connections between cells, like a wiring diagram. But the wiring of the brain says nothing about what its individual units are made of. To understand what makes brain cells diverse, Lein says neuroscientists are borrowing tricks from the world of genomics.