Scientists discover mice can sing and mimic complex sounds

Researchers found the mice have certain brain features, somewhat similar to humans and song-learning birds, which they may use to change their sounds.

"We are claiming that mice have limited versions of the brain and behaviour traits for vocal learning that are found in humans for learning speech and in birds for learning song," said Duke neurobiologist Erich Jarvis, who led the study.

The discovery contradicts scientists' 60-year-old assumption that mice do not have vocal learning traits at all.

"If we're not wrong, these findings will be a big boost to scientists studying diseases like autism and anxiety disorders," said Jarvis, a Howard Hughes Medical Institute investigator.

"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 vocalisations," he said.

The research suggests the vocal communication pathways in mice brains are more similar to those in human brains than to sound-making circuits in the brains of chimpanzees and other non-human primates.

"This is a very important study with great findings," said Kurt Hammerschmidt, an expert in vocal communication at the German Primate Centre who was not involved in the study.

Jarvis and researcher Gustavo Arriaga from Tulane University tested male mice for vocal learning traits as part of a larger project to study speech evolution in humans.

Vocal learning appears to be unique to humans, songbirds, parrots and hummingbirds and scientists define it with five features related to brain structure and behaviour.

Since scientists have never found the features in other animals, "I almost expected every experiment in mice to fail," Arriaga said.

Arriaga first used gene expression markers, which lit up neurons in the motor cortex of the mice's brain as they sang.

He also used an injectable tracer, which mapped the signals controlling song as they moved from the neurons in the motor cortex to those in the brainstem and then to the muscles in the larynx.

"The evidence of direct projection from these motor cortex regions is a great finding," Hammerschmidt said.

Researchers found that when two male mice were placed in the same cage with a female, the males' pitch began to converge after seven to eight weeks.