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Human “language gene” found to work in mice, too

The gene, called Foxp2, was first linked to language in a study of a family half of whose members had severe speech and grammar impairments. Researchers found all the affected members had a mutation in the gene. 

The gene is found on a region of a human chromosome—chromosome 7—linked to other disorders that affect speech, including autism.

Mice also have a version of the gene. In a new study, researchers engineered mice with either one or both copies of it disrupted, to learn more about its role in communication. 

The treatment curbed the ability of the mice to emit squeaks called ultrasonic vocalizations when separated from their mother and littermates, said the study’s leader, Joseph D. Buxbaum of the Mount Sinai School of medicine in New York City.

Mice with both copies disrupted completely stopped making the sounds—which are too high-pitched for human hearing—while mice with one disrupted gene made significantly fewer of them, the researchers said. 

The doubly-disrupted mice also displayed severe motor skill impairment and died early, they added; single-copy mice had more modest, but still noticeable, developmental delays.

“Our findings demonstrate that Foxp2 subsumes communication across species, and, as a result, we can legitimately use the mouse to learn about the neurobiology of human speech and articulation,” said Buxbaum, whose paper was published online last week in the research journal Proceedings of the National Academy of Sciences.

But other researchers have found the human Foxp2 is slightly different from that of animals, including our ape relatives, suggesting evolutionary forces reshaped the gene not long ago. These findings were published in the Aug. 22 issue of Nature, another journal.

A major question is exactly what the gene does to promote communication.

In mice, Foxp2 disruption didn’t seem to affect the vocal tract, said the Mount Sinai researchers, suggesting the gene doesn’t have roles in that area. Rather, they said, studies suggest it influences cell development in the cerebellum, a brain region considered responsible for coordinating complex voluntary muscular movements, maintaining posture and balance. 

“It has been hypothesized that speech is somehow a finer example of a motor pathway—a more demanding, more subtle pathway, but still a motor pathway,” said Buxbaum. The mouse studies support this idea, he added.

The Foxp2 mice may also allow researchers to investigate how this gene is related to autism, the researchers said. A few studies suggest that Foxp2 is an autism-susceptibility gene, they added, but most scientists disagree with this conclusion. However, Foxp2 is also a so-called transcription factor, something that controls the activities of other genes. 

“The Foxp2 mouse can now be used to determine which genes are abnormally expressed [activated] in the cerebellum in these animals,” said Buxbaum. “Those genes might be legitimate autism-susceptibility genes.”

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