Brain’s growth, networks unveiled in new maps

Human, mouse brains probed in detail

MAPPED OUT  This top-down view of the mouse brain shows spindly connections made by neurons in distinct brain regions (marked by different colors).

Allen Institute for Brain Science

Two new maps illustrate human and mouse brains in sharp relief, offering insights into how brains are built and operate. The studies, led by scientists at the Allen Institute for Brain Science in Seattle and published  April 2 in Nature, join other recent large-scale descriptions of the brain (SN Online: 3/27/14; 2/17/14).

The new human map covers territory that’s still forming. By studying levels of gene activity in four postmortem fetal brains, researchers were able to describe how genes in different regions orchestrate the growth of the human brain. Some of these genes have been linked to developmental problems such as autism spectrum disorders. Having a detailed map of when and where these genes are active might provide clues to complex neural disorders, the researchers write.

The mouse map traces multitudes of spidery neural connections in an adult brain. The resulting grid is based on about 15 to 20 percent of neurons situated in 295 distinct anatomical locales that cover the entire mouse brain. The map will serve as a valuable resource for scientists intent on figuring out how brains handle information, the authors write.

Laura Sanders is the neuroscience writer. She holds a Ph.D. in molecular biology from the University of Southern California.

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