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Mapping the human brain

July 21, 2016

Understanding the complexities of human brain function requires having a map.  Work from the Allen Institute and a new paper published this week by a team at Washington University in St. Louis in the journal Nature highlight two distinct approaches to brain mapping and how they can work together to reveal the structure and function of the brain.

A team of researchers led by David Van Essen at Washington University in St. Louis has published this week an exciting new map of the human brain that delineates regions of the brain based on their anatomy and function. The map combines data from many individuals using a variety of combined neuroimaging techniques, including structural magnetic resonance imaging (MRI), functional MRI, and diffusion tensor imaging, which traces how water flows along fiber tracts in the brain.

Their map puts all of these modalities together to divide, or parcellate, the neocortex into discrete areas. It also provides a useful framework for other functional studies of the brain to see which regions of the brain their studies target.

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Instead of this kind of top-down approach, the Allen Institute tackles this problem from a bottom-up vantage point by mapping gene usage as it varies across the human brain. Since function is a reflection of anatomy, and anatomy is a consequence of gene expression, this approach uses the molecular code to understand structure, function and how gene disruption could lead to disease.

These two mapping approaches complement each other in key ways, showing some similar outcomes and other points of difference. For example, the functional map shows these discrete regions of the brain with fairly concrete outlines. In contrast, gene expression boundaries are less discrete, with graded expression across most areas of the cortex.

“Looking at the convergence between these two approaches provides some interesting perspectives on how the human brain is organized,” says Ed Lein, Ph.D., Investigator at the Allen Institute for Brain Science. “Both approaches—the molecular and the functional—are key to understanding the brain as a whole, and looking at their intersection is a ripe area for study.”

“We collaborated with the Van Essen team to compare our gene expression data and functional connectivity from the Human Connectome Project, published last year in Nature Neuroscience,“ says Mike Hawrylycz, Ph.D., Investigator at the Allen Institute for Brain Science. “This new parcellation opens up many new opportunities for comparison to extend our understanding of brain architecture.”

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