A high-resolution map of the human brain in utero is providing hints about the origins of brain disorders including schizophrenia and autism.
The map shows where genes are turned on and off throughout the entire brain at about the midpoint of pregnancy, a time when critical structures are taking shape, researchers reported Wednesday in the journal Nature.
"It's a pretty big leap," says Ed Lein, an investigator at the Allen Institute for Brain Science in Seattle who played a central role in creating the map. "Basically, there was no information of this sort prior to this project."
Having a map like this is important because many psychiatric and behavioral problems appear to begin before birth, "even though they may not manifest until teenage years or even the early 20s," says Dr. Thomas Insel, director of the National Institute of Mental Health.
The human brain is often called the most complex object in the universe. Yet its basic architecture is created in just nine months, when it grows from a single cell to more than 80 billion cells organized in a way that will eventually let us think and feel and remember.
"We're talking about a remarkable process," a process controlled by our genes, Lein says. So he and a large team of researchers decided to use genetic techniques to create a map that would help reveal this process. Funding came from the 2009 federal stimulus package. The project is part of the BrainSpan Atlas of the Developing Human Brain.
The massive effort required tens of thousands of brain tissue samples so small that they had to be cut out with a laser. Researchers used brain tissue from four aborted fetuses, a practice that the Obama administration has authorized over the objections of abortion opponents.
Researchers tested each sample to see which genes were turned on and off in each tiny bit of brain. This helped the team figure out which types cells were present at specific points in the brain and what those cells were doing, Lein says.
The resulting map, which is available to anyone who wants to use it, has already led to at least two important findings, Lein says. "The first is that many genes that are associated with brain disorders are turned on early in development, which suggests that these disorders may have their origin from these very early time points."
Written By: Jon Hamilton
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