In the early 1900s, neurologist Korbinian Brodmann drew some of the first diagrams of the human cortex by hand, based on differences in cellular architecture that he could see under a microscope.
For more than a century, scientists have continued using those maps, as well as those of neuroanatomists that followed in Brodmann’s footsteps.
To construct the map, a team led by neuroscientist Mathew Glasser at Washington University Medical School used imaging data collected from 210 healthy young adults participating in the Human Connectome Project, a US government-funded initiative to map the brain’s structural and functional connections.
Previous attempts at mapping the cortex—the wrinkly, outermost layers of the brain responsible for sensory and motor processing, language, and reasoning—have had mixed results because some were based on small samples and others focused on just one aspect of brain structure or function. To create a more detailed map, the team looked at four measures of structure and function, including the thickness and number of folds in the cortex and what activity different regions displayed in a functional magnetic resonance imaging scanner during a given task. They gathered their data from 210 healthy adults, and then trained a machine-learning algorithm to detect distinct regional “fingerprints.”
The program defined 180 distinct areas, including nearly 100 that have never been described before, the scientists report today in Nature. The sharper, multilayered map will allow for more detailed comparisons between humans and other primates, shedding light on how our brains evolved, the scientists say. It could also prove a boon to neurosurgeons, as they decide where to insert their scalpels.