In the subsoil of Central America's cloud forests, musical mice trill out songs to each other. Now a study of the charismatic creatures reveals how their brains orchestrate these fast duets.
The results, published on March 1 st Science, show that the brain of the singing mice divides the musical work. A brain system directs the note patterns that make up the songs, while another coordinates the duets with another mouse, which are performed with accuracy to the nearest second.
The study suggests that "an original animal from the cloud forest of Costa Rica could give us a new idea" of rapid exchanges between people, says study co-author Michael Long, a neuroscientist at the School of Medicine.
The quirks abound in these mice, known as Alston's singing mice (Scotinomys teguina). Like famous singers with extreme requirements for green rooms, these mice are "divas," Long says, requiring larger terrariums, exercise equipment, and a very special diet.
In the laboratory, standard mouse feeding does not cut it; Instead, the singing mice feast on worms of fresh flour, dry cat food and fresh fruits and berries, says Bret Pasch. The biologist at Northern Arizona University in Flagstaff has been studying these mice for years, but did not participate in this study.
Mice are also, of course, strong. "They are very noisy," says Pasch, especially within the confines of a laboratory. "When an animal calls, it's like a symphony going off," repeat the calls. In nature, it is thought that these duos attract friends and impose on the territory.
SING OFF KEY Two singing mice create a quick-fire duo. One study suggests that the timing of their songs is controlled by an area of the brain called the orofacial motor cortex.
It is thought that a brain system controls the content of songs. But another part – the orofacial motor cortex, or OMC – orchestrates the synchronization in a fraction of a second needed for the duets of mice, discovered Long and his colleagues.
When the team cooled the mouse's MOC, which slowed the activity of these nerve cells, the songs lengthened, suggesting that the brain region normally controls the timing of the song. And when the researchers used a drug to silence the MOC, the mice had trouble singing in duet in response to the call of another mouse.
"In a very clear and convincing way, they show that this structure is involved in this behavior," says neurobiologist Steffen Hage of the University of Tübingen in Germany who wrote an accompanying commentary in Science.
The MOC of the singer mouse may not align exactly with the areas of the brain used to stimulate human chatter. Nevertheless, the results may ultimately give clues to human conversations, which often take place at the same pace. This lawsuit could eventually lead to therapies for disorders that affect communication, such as stroke and autism, says Long.
The results also highlight the benefits of creatively studying various animals. "As we install microphones on a larger number of species, we find that a lot of them use their voices," Pasch says.