(CN) — A detailed map of the cerebral cortex has presented a unique opportunity to analyze and treat a host of mental illnesses, work previously stifled by outdated technology and limited knowledge of the brain’s complex inner workings.
In a study published Wednesday in the journal Nature, researchers at Washington University School of Medicine in St. Louis provide detailed analysis of the left and right hemispheres in the brains of 210 healthy patients, presenting a map of 180 areas based on physical difference — including 97 previously unknown areas.
The findings can help scientists compare healthy brains with those of mentally ill patients to identify unique physical differences, developments that could provide quicker diagnoses and nuanced treatments in the future.
“The brain is not like a computer that can support any operating system and run any software,” study co-author David Van Essen said. “Instead, the software — how the brain works — is intimately correlated with the brain’s structure, its hardware, so to speak. If you want to find out what the brain can do, you have to understand how it is organized and wired.”
The cerebral cortex — the outermost layer of the brain, which is crumpled to fit in the skull, giving the organ its distinct folds and wrinkles — is the most dominant structure involved in sensory perception and attention, as well as distinctly human functions such as abstract thinking, tool use and language.
Data gathered by the sophisticated technologies of the Human Connectome Project, a National Institutes of Health initiative led by Van Essen, was used to analyze the brain images from 210 healthy young adult participants in the project.
Instead of isolating a specific biological property of the brain — connectivity, function, topography or architecture — the researchers incorporated all four criteria to establish border lines around each “country” within the cortex.
Matthew Glasser, the study’s lead author, initially began studying the connections between language areas of the brain after growing frustrated with the first map of the human cortex, outlined by German neuroanatomist Korbinian Brodmann in the early 20th century.
To make an updated map, the researchers combined the amount of insulation around neuronal cables and the measures of thickness of the cortex, using MRI scans of the resting brain and of the brain performing simple tasks such as talking or listening to a story.
“We ended up with 180 areas in each hemisphere, but we don’t expect that to be the final number,” Glasser said. “In some cases, we identified a patch of cortex that probably could be subdivided, but we couldn’t confidently draw borders with our current data and techniques. In the future, researchers with better methods will subdivide that area. We focused on borders we are confident will stand the test of time.”
Areas like 55b, which lights up with activity when a person listens to a story, are clearly involved in specific tasks. Other areas are involved in controlling movement or contain a map of a person’s field of vision.
But most areas may never be identified since they perform more than one task, by coordinating information from several different signals.
The researchers used a machine-learning classifier to recognize the unique fingerprints of the cortical areas. The classifier was able to detect 96.6 percent of the cortical areas in new patients, correctly locate areas in individuals with atypical parcellations — regions defined by similarities — and replicate the group parcellation.
Since physiological differences between people has stifled research into the brain in the past, the scientists precisely aligned the brains to a common coordinate system before analysis by using an algorithm developed at Oxford University and incorporating the highest quality MRI data available.
The scientists hope that their findings and tools can be used by future researchers in developing more nuanced maps of the brain and guiding treatment for neurological illnesses like different types of dementia, which are associated with degeneration in different areas of the brain.
“We were able to persuade Nature to put online almost 200 extra pages of detailed information on each of the 180 regions as well as all of the algorithms we used to align the brains and create the map,” Van Essen said. “We think it will serve the scientific community best if they can dive down and get these maps onto their computer screens and explore as they see fit.”
Image: Matthew F. Glasser, David C. Van Essen
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