Protein shown to help build body maps raises questions about individual differences in function
Boston, MA March 30, 2000 A single gene expressed in the brain can change a long-standing icon of basic neuroscience that was until now thought to be shaped mostly by neural input from the body's periphery, Harvard Medical School researchers have found.
The sensory homunculus is the familiar textbook caricature of a human being spread out improbably over the surface of the brain. It depicts how much space the brain allocates to our different body parts when it comes to feeling out the world around us. Its wildly uneven proportions are generally thought to arise in response to the activity of sensory neurons feeding information to the brain. In the April Nature Neuroscience, however, researchers led by John Flanagan, HMS associate professor of cell biology, report that a protein previously known to establish maps of the visual world in lower brain centers also plays a prominent role in imprinting a proper body map on the brain's cortex.
The work is intriguing because previous research in other areas has correlated representation in the brain with functional abilitysuggesting, in essence, that more important things get more brain space. "That we can modify this with one genetic change was totally unexpected," says Flanagan.
His group has not yet analyzed how the mice's distorted body map affects them, but he says that generally "it is not too much of a stretch to think that if you change the scale of representation in the cortex, you change behavior."
Most parents marvel at how their children differ in their interests. Where could those differences come from? Genetics partly addresses this question by trying to link genes to specific behaviors, such as a propensity for adventurousness. "But in terms of these maps, there is no previous evidence for a genetic basis to how they could be controlled," says Flanagan.
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Contact: Peta Gillyatt
gillyatt@hms.harvard.edu
617-432-0443
Harvard Medical School
29-Mar-2000