WASHINGTON, D.C.--Biologists trying to understand the brain typically spend thousands of hours determining what genes are active in specific neural regions. Now they can save themselves the trouble, thanks to the completion of a Web-based brain atlas announced here today. Experts say the map will accelerate the search for drugs to treat psychiatric illnesses and help address fundamental questions about the development and function of different brain structures.
Funded by Microsoft co-founder and philanthropist Paul Allen, the brain atlas project took 3 years and $40 million to complete. Researchers at the Allen Institute of Brain Science in Seattle, Washington, analyzed over 250,000 slices of mouse brain to determine which of the 21,000 or so known mouse genes are turned on in the brain, as well as where and to what extent.
The map shows that 80% of genes in the mouse genome are expressed in the brain--higher than the 70% figure that researchers previously thought. And roughly 25% of those genes occur only in specific parts of the brain, says Allen Jones, chief scientific officer for the project. Among the things that the dataset will allow researchers to do, he says, is figure out which cells tend to express the genes in similar ways. That could reveal new structures in the brain.
The atlas, whose data has been made available in installments since December 2004, is already saving researchers a lot of time and trouble. Joanne Wang, a pharmaceutics researcher at the University of Washington, Seattle, works with molecules that ferry cargo--and potentially drugs--into and out of the brain. Doing this requires understanding where and how abundantly the molecules' genes are expressed in the brain, which is "not a trivial task for individual labs," she says. It took a graduate student in her lab almost a whole year to map the brain expression pattern of a single transporter gene, she says. Now, anyone can simply type a gene's name into the site and view its expression profile.
Jones says the institute is currently embarking on a project to create a similar gene expression map for the human cortex; he and his colleagues have already begun talks with brain banks and neurosurgeons. The new project will provide important insights into genetic drivers of the overall structure of the cortex as well as how developmental abnormalities unfold, says Jones.