First Draft Atlases of the Developing Human and Mammalian Brain Reveal Thousands of Cell Types

Scientists publish first draft atlases of the developing brain

Researchers have released a comprehensive first draft of atlases charting how brain cell types emerge and mature from the earliest embryonic stages through adulthood in humans and other mammals. The work, led by teams in the U.S. BRAIN Initiative Cell Atlas Network (BICAN) and published across Nature and companion journals, maps when different brain cells are born, how they differentiate, and how gene activity changes over time.

Scope and methods: The project analyzed cells from human and mouse brains, with additional data from monkeys, and combined single-cell and developmental genomics to trace cell lineages, transcriptional programs, and timelines of differentiation across brain regions.

Key findings

• Scientists documented thousands of cell types and states; prior work catalogued over 5,000 cell types in the mouse brain and the new atlases show comparable diversity in humans.
• Investigators identified important genes and regulatory programs that guide brain development and found both conserved patterns across species and human-specific features — for example, a prolonged period of cortical cell differentiation consistent with the extended human developmental timeline.
• New, previously unrecognized cell types were discovered in regions including the neocortex (involved in higher cognition), the striatum (linked to movement and other functions), and the hypothalamus (which regulates vital physiological processes).
• One study found that some cells in human brain tumors resemble embryonic progenitor cells, suggesting that certain cancers may reactivate developmental programs to drive malignancy.

Implications

These atlases provide a far more detailed framework for understanding normal brain development and for pinpointing when and where developmental processes go awry in disorders such as autism, attention deficit hyperactivity disorder (ADHD), schizophrenia, and in brain cancers. Comparing human and animal development will improve interpretation of animal models and help guide more precise gene- and cell-based therapeutic strategies.

"Our brain has thousands of types of cells with extraordinary diversity...these diverse cell types work together to generate a variety of behaviors, emotions and cognition," said Hongkui Zeng of the Allen Institute. UCLA neuroscientist Aparna Bhaduri added that the atlases reveal detailed "pieces" of the developing brain that were previously elusive.

Next steps: The atlases are a first draft. Researchers will continue to expand the datasets, increase temporal and spatial resolution, and integrate functional and clinical data to better map neurodevelopmental and neuropsychiatric vulnerabilities and to translate insights into therapies.

Published by: The studies are part of the NIH BRAIN Initiative Cell Atlas Network (BICAN) and appear in Nature and related journals.