Mice Grow Big Brains With an Extra Gene

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Adding an extra version of a single gene makes mice grow big brains--brains so large they have to fold up, much as human brains do, to fit inside the skull, researchers said. It is not yet clear whether the mice are smarter (they were all killed soon after birth), but the scientists said they were surprised that one gene had such a strong effect and said they would conduct further experiments.

“I know the most interesting question was whether they learned to play Mozart, but we don’t know,” said Dr. Christopher Walsh of Brigham and Women’s Hospital and Harvard Medical School in Boston, who led the study.

Walsh and Anjen Chenn started with a protein called beta-catenin, which helps control cell division. Walsh and Chenn genetically engineered mice, adding extra beta-catenin that would become overactive specifically in brain tissue.

To their surprise, they reported in Friday’s issue of the journal Science, the mice developed large, folded brains that looked like human brains. Mouse brains normally have a smooth surface.