Researchers at Johns Hopkins Medicine, working with collaborators around the world, have combined data from nearly 200 published studies and more than 30 million cells into a detailed map of how the human neocortex forms. The neocortex, the brain's outermost layers, handles thinking, sensory processing, memory storage and decision-making, and the new atlas tracks the cell transitions and gene activity that assemble it. The work is available through Nature and Nature Neuroscience.
Carlo Colantuoni, an adjunct professor of neurology at Johns Hopkins Medicine and the Institute for Genome Sciences at the University of Maryland School of Medicine, said the aim is to understand how the neocortex is built at a cellular level and to find clues to the earliest stages of developmental delays and brain disorders. That span matters: the same tissue is implicated in conditions beginning in the womb, such as microcephaly, in childhood conditions like autism spectrum disorder, which affects roughly 1 in 31 U.S. children, and in Alzheimer's disease, estimated to affect more than 7 million U.S. adults, including 1 in 9 people age 65 and older.
Alongside the human map, the team published mammal and mouse atlases. Comparing them showed that gene expression programs which existed as diffuse networks millions of years ago became concentrated in human neural stem cells, driving the expansion of the human neocortex. The researchers also charted how long neurons take to mature: weeks in a mouse, but many years in humans - a drawn-out developmental window that lets the human brain learn to interpret complex social, environmental and sensory input.
The practical payoff is access. The atlases are posted as an open web portal that scientists without coding expertise can use to examine the expression of individual genes, follow modules of genes that act together during development, and add their own data to the resource. Colantuoni frames these brain-charting efforts as infrastructure for studying disease mechanisms across the lifespan rather than an answer to any one condition - a starting point for research into where neurodevelopmental and later-life brain disorders begin.