A ground-breaking Human Brain Cell Atlas just dropped
The Complexity of the Brain: A Survey of Gene Regulation and Expression in Hundreds of Brain Cell Types through a Microscopical Lens
“Prior to this data set, it was just a hypothesis that the brain was really complicated,” adds Amy Bernard, the director of life sciences at the Kavli Foundation, who was not involved in this project. Physicists often think about the brain in terms of connections between cells, like a wiring diagram. The electrical activity of the brain doesn’t say anything about what individual units are made of. Lein says that neuroscience is using tricks from thegenomics world to understand brain cells.
Historically, it’s been nearly impossible to get a handle on the complexity of the human brain. With so many interconnected pieces, “it’s not really a single organ—it’s like a thousand organs,” says Ed Lein, a senior investigator at the Allen Institute for Brain Science who helped lead the atlas project.
Other studies drilled into the mechanisms of gene regulation and expression in different cells. Using tissue samples from three donors, a group of scientists led by Joseph Ecker studied the brain through an epigenetic lens. They analysed chemical markers that switch genes on or off in more than 500,000 individual cells. There were almost 200 brain cell types identified, thanks to the various molecule that acted as switches. The same cell may have the same gene, but it may have different characteristics in the brain. There were two switches at the back and front of the brain, one at the front. “There are remarkable regional differences,” says study co-author Wei Tian, a computational biologist at the Salk Institute.
The next step for the BICCN team is to sequence more cells from all parts of the brain, says Ren. The researchers will also work with more tissue samples to build a picture of how the human brain can vary across populations and age groups. Ren says that this is only the beginning.
