In 1909, German neurologist Korbinian Brodmann released the first map of the human brain. Slicing ultra-thin sections, he looked at the minute structures within the gelatinous mass under the microscope and identified regions of different cell types. Brodmann listed 43 discrete areas of the cerebral cortex, the brain’s outermost layer involved in attention, perception, language and abstract thinking.
Over the last century, other scientists slowly refined the map, increasing the number of brain areas to 83. Now, a new map from researchers at Washington University’s school of medicine more than doubles that total, adding another 97 and raising the number of known brain regions to 180.
The researchers created the map from MRI data collected by the government-funded Human Connectome Project. Using data from 210 of the subjects from this project, the researchers defined brain areas in several ways, including both brain activity and structure. Some areas are demarcated by the thickness of the cortex. Others are defined by the myelin insulation around the neuronal cables or by their connectivity with the rest of the brain. Still other regions correspond with areas that activate while performing simple tasks, such as talking or listening to a story.
Because the size and shape of each brain is unique, it is difficult for neurologists to directly compare them. So in the new study, researchers used an computer program to help them line up and correlate the regions. They then tested their program on 210 other subjects and it correctly identified the regions 96.6 percent of the time, Carl Zimmer reports for The New York Times.
In fact, the computer program became very efficient at comparing and mapping the brains, even finding that area 55b, which is involved with language, is split into two sections in 12 of the patients, according to Zimmer. It also showed that a large area near the front of the brain thought to be one region is actually a dozen smaller brain areas.
The map is still a work in progress, Matthew F. Glasser, a neuroscientist at Washington University School of Medicine and lead author of the research, tells Zimmer. In fact, the team published 200 extra pages of material online so other researchers can pick through and refine their work. “This map you should think of as version 1.0,” he says. “There may be a version 2.0 as the data get better and more eyes look at it. We hope the map can evolve as the science progresses.”
While the map is a big step forward, it will take a lot more effort to validate the new regions of the brain, many of which may still exist in subdivisions. DNA testing will also reveal whether discrete regions use different genes from one another.
“It is analogous to having a fantastic Google Earth map of your neighborhood, down to your individual back yard,” Rex Jung, a neuropsychologist at the University of New Mexico tells Linda Geddes for Nature. “Yet, you cannot really see how your neighbors are moving around, where they are going or what sort of jobs they have.”
Still, the new map could be extremely important for research on conditions like autism, schizophrenia, dementia and epilepsy, giving scientists a detailed brain template of a healthy brain they can use as for comparison.