In mid-July, scientists at the Washington University Medical School, Saint Louis, published a study that inspired awe in fellow researchers — an updated map of the cerebral cortex of the human brain, identifying nearly 100 new areas.
The exceedingly intricate and updated map, published in the journal Nature under the title “A multi-modal parcellation of human cerebral cortex,” is likely to not only be invaluable for scientists worldwide in their understanding of the normal workings of the brain, but also in helping researchers to learn how normal processes go haywire in conditions like Alzheimer’s disease.
“These new insights and tools should help to explain how our cortex evolved and the roles of its specialized areas in health and disease, and could eventually hold promise for unprecedented precision in brain surgery and clinical work-ups,” Bruce Cuthbert, PhD, acting director of National Institute of Mental Health, a branch of the National Institutes of Health that co-funded the research as part of The Human Connectome Project, said in a NIH release.
Interest in understanding the brain by mapping its various regions is not new. During the 19th century, this was a popular field of research. Scientists such as Paul Broca and Carl Wernicke identified brain areas linked to speech production — to this day referred to as Broca’s and Wernicke’s areas.
In 1907, a brain scientist called Korbinian Brodmann took on a somewhat more ambitious approach, publishing a brain map of 52 hand-drawn regions, based on observations made during long hours at a microscope, where he mapped differences in how cells were organized. Until a few weeks ago, this brain map had been only modestly improved with the addition of findings from research teams. These studies were equally limited, looking at a particular aspect of one brain region at a time, such as the organization of neurons in postmortem tissue or the brain blood flow (where increased blood flow suggests an area is active) of a person during a particular task.
The new study used an entirely different approach, made possible by the efforts of The Human Connectome Project — a large consortium of scientists from Washington University, University of Minnesota, and Oxford University in the U.K. In contrast to the people pioneering the field and many scientists since, the project has at its hand a range of methods exploring various aspects of each brain area.
Project researchers used brain scans to reveal anatomical features, and volunteers had their brains explored with scans measuring brain activity both when they were doing nothing and when they were focused on solving tasks that tested, among other things, their visual processing, memory, attention and emotional processing. Volunteers also underwent behavioral tests with their heads in the scanner.
Scientists used data from 210 healthy young adults to build a first version of the map. In this way, they identified 180 regions per brain hemisphere characterized by stark differences in how nerve cells were organized, and how they worked and connected to one another. Of the 180 regions, 97 were new and the remaining 83 had been previously described — basically doubling the resolution of previous brain maps.
To test if the map was reliable, researchers then used automated machine learning, a technology better known as artificial intelligence, to scan another 1,100 subjects. The automated process did a good job, identifying 96.6 percent of the regions mapped by the research team. But it turned out to do more than just confirm the map — it identified differences, too. It found individuals whose brain map was “atypical,” showing it will likely be an invaluable tool for studying diseases such as Alzheimer’s.
The map will continue to improve as more, higher resolution data is added. “We’re thinking of this as version 1.0,” Matthew Glasser, a lead study author with the Department of Neuroscience at Washington University Medical School, said in a Connectome Project release. “That doesn’t mean it’s the final version, but it’s a far better map than the ones we’ve had before.”
The tool is being made available to researchers worldwide, free of charge.
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