Dr. Erich Jarvis spends a lot of time with songbirds. At his Duke University lab, Jarvis, a Stereo Investigator user, studies the neurobiology of vocal communication. Since his feathered friends learn song much like humans learn speech, they’re a favorite model. But Dr. Jarvis says mice sing too, and new research says they can learn new tunes.
“We investigated the mouse song system and discovered that it includes a motor cortex region active during singing, that projects directly to brainstem vocal motor neurons and is necessary for keeping song more stereotyped and on pitch,” the authors said in their study published in PLoS ONE.
The discovery is controversial as it challenges longstanding beliefs that mice can not learn vocal behavior, but if Dr. Jarvis’ findings are true, it will be a breakthrough for scientists studying autism and anxiety disorders, according to a Duke University press release.
“The researchers who use mouse models of the vocal communication effects of these diseases will finally know the brain system that controls the mice’s vocalizations,” Dr. Jarvis said in the press release.
While studying speech evolution in humans, Dr. Jarvis and his colleagues tested male mice for vocal learning – an ability only believed to be shared by humans, songbirds, parrots and hummingbirds.
The research team used gene expression markers to see which neurons fired in the motor cortex when the mice sang. The researchers then damaged these neurons, and found the mice could no longer stay on pitch. Using an injectable tracer, they mapped a signal pathway from the motor cortex, through the brainstem, to the larynx muscles.
To test whether mice could learn vocalizations, the researchers placed pairs of male mice in a cage with one female mouse. After seven to eight weeks, the male mice had changed their tunes so they were singing the same pitch.
“Our results show that mice have the five features scientists associate with vocal learning. In mice, they don’t exist at the advanced levels found in humans and song-learning birds, but they also are not completely absent as commonly assumed,” he said.
“Of mice, birds, and men: the mouse ultrasonic song system has some features similar to humans and song-learning birds,” Arriaga, G. et. al. (2012) PLOS ONE. 7(10): e46610. doi:10.1371/journal.pone.0046610
[Image via the Erich Jarvis Lab website]