The BRAIN Initiative Cell Atlas Network (BICAN), a global effort to identify and characterize every cell in the brain, has published a landmark collection of findings: 26 papers across Cell Press journals.
By charting nearly 25.5 million individual brain cells, the interdisciplinary team produced a 3D, single-cell atlas of the basal ganglia, the deep-brain hub for movement, habit, and reward. This will broaden scientists’ understanding of what may go awry in neurological conditions such as Parkinson’s disease, Huntington’s disease, Tourette’s syndrome, obsessive-compulsive disorder, and addiction.
The cellular roadmap also sets shared standards for tissue processing, data sharing, and anatomical mapping across mammalian brains. Hundreds of researchers can now compare and build on one another’s work, and that framework is already guiding efforts to map the rest of the brain.
As part of this collection, neuroscientist Michael L. Platt of the School of Arts & Sciences, Perelman School of Medicine, and Wharton School collaborated with researchers at Arizona State University and the University of Washington to study how cells age in 11 different brain regions.
“Different people age at different rates biologically,” says Platt. “But also, different tissues and different cells age at different rates.”
The researchers found that glia changed far more with age than neurons did. Platt describes glia as the cells that “provide support and nutrition for neurons, and in particular they secrete myelin, which is the insulation that covers the wires that one neuron uses to connect to another.”
“And when that falls apart,” he says, “that can lead to a whole host of degenerative outcomes.”
Inflammation-associated immune cells called microglia increased in nearly every region studied. Many of these age-related shifts overlapped with molecular signatures of Alzheimer’s disease.
Platt says there was a striking difference between the sexes, noting how in most cell types showing a sex bias, female brains looked molecularly “older” than male brains of the same age — a pattern that parallels women’s higher risk of Alzheimer’s.
The exception was spiny projection neurons in the basal ganglia. These cells showed faster aging in male brains, which may help explain why Parkinson’s disease is more common in men.
In a related paper published this June in Science, Platt, co-senior author and Penn alumnus Noah Snyder-Mackler of Arizona State, and Vanderbilt University’s Amanda Lea mapped DNA methylation—a chemical tag on DNA that tracks age—across 14 tissues, finding that age left tissue-specific marks. The team also found that early-life adversity, such as losing a mother, left a more coordinated imprint across the body, though not one that simply made tissues look older.
“Aging is the single greatest risk factor for neurodegenerative disease, but we still don’t fully understand how it unfolds in the brain,” says Snyder-Mackler. “This atlas gives us a detailed roadmap of how aging progresses across cell types, brain regions and even between males and females.”
Both studies suggest that aging looks different in different tissues and cell types rather than following one uniform script. The Cell data add that it is also continuous, Platt explains, as many cell populations changed steadily from early life onward, suggesting that aging extends developmental programs rather than being a separate phase.
“The life course is just this differential expression and regulation of processes that are initiated at birth, or maybe even before birth, and carry through until the end of your days on this planet,” Platt says.
Michael L. Platt is the James S. Riepe Penn Integrates Knowledge University Professor with appointments in the Perelman School of Medicine, School of Arts & Sciences, and Wharton School at the University of Pennsylvania.
This work received support from the National Institutes of Health (Awards U01-MH121260, R01-AG060931, R00-AG051764, R00-AG075241, R01-HG010632, R01-MH118203, R01-MH096875, R37-MH109728, R21-AG073958, R01-MH108627, R56-AG071023, T32-AG000057, T32-AG044402, T32-AG082658, P40-OD012217 and UM1-MH130981), the National Science Foundation (Awards TIP-2110037 and BCS-1800558) and the Kaufman Foundation (Award KA2019-105548).
Cell
Experimental study
Animals
Single-cell, multi-region profiling of the macaque brain across the lifespan
12-Nov-2026
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