Scientists reveal a detailed cell map of the mammalian brain

For the first time, an international team of researchers has created a full-cell atlas of a whole mammalian brain. This atlas serves as a map of the mouse brain, describing the kind, location, and chemical information of over 32 million cells as well as information on cell connectivity.

The mouse is the most often used vertebrate experimental model in neuroscience research, and its cellular map paves the door for a better understanding of the human brain – probably the world’s most powerful computer. The cell atlas also provides the groundwork for a new generation of precision treatments for those suffering from mental and neurological illnesses of the brain.

The findings were published in Nature.
“The mouse atlas has brought the intricate network of mammalian brain cells into unprecedented focus, giving researchers the details needed to understand human brain function and diseases,” said Joshua A. Gordon, M.D., Ph.D., Director of the National Institute of Mental Health, part of the National Institutes of Health.

The cell atlas describes the types of cells in each region of the mouse brain and their organization within those regions. In addition to this structural information, the cell atlas provides an incredibly detailed catalog of the cell’s transcriptome — the complete set of gene readouts in a cell, which contains instructions for making proteins and other cellular products.
The transcriptomic information included in the atlas is hierarchically organized, detailing cell classes, subclasses, and thousands of individual cell clusters within the brain.

The atlas also characterizes the cell epigenome — chemical modifications to a cell’s DNA and chromosomes that alter the way the cell’s genetic information is expressed — detailing thousands of epigenomic cell types and millions of candidate genetic regulation elements for different brain cell types.

Together, the structural, transcriptomic, and epigenetic information included in this atlas provide an unprecedented map of cellular organization and diversity across the mouse brain.
The atlas also provides an accounting of the neurotransmitters and neuropeptides used by different cells and the relationship among cell types within the brain.

This information can be used as a detailed blueprint for how chemical signals are initiated and transmitted in different parts of the brain. Those electrical signals are the basis for how brain circuits operate and how the brain functions overall.

“This product is a testament to the power of this unprecedented, cross-cutting collaboration and paves our path for more precision brain treatments,” said John Ngai, PhD, Director of the NIH BRAIN Initiative.”

Of the 10 studies included in this collection, seven are funded through the NIH BRAIN Initiative Cell Census Network (BICCN), and two are funded through the larger NIH BRAIN Initiative.
The core aim of the BICCN, a groundbreaking, cross-collaborative effort to understand the brain’s cellular makeup, is to develop a comprehensive inventory of the cells in the brain — where they are, how they develop, how they work together, and how they regulate their activity — to better understand how brain disorders develop, progress, and are best treated.

“By leveraging the unique nature of its multi-disciplinary and international collaboration, the BICCN was able to accomplish what no other team of scientists has been able to before,” said Dr. Ngai.

“Now we are ready to take the next big step — completing the cell maps of the and the nonhuman primate brain