Like guys who imitate Luciano Pavarotti or Justin Bieber to get the girls,male mice may also match the pitch of other males ultrasonic serenades. A new study has revealed that mice also 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 oversaw the study. The discovery contradicts scientists 60-year-old assumption that mice do not have vocal learning traits at all. If were not wrong,these findings will be a big boost to scientists studying diseases like autism and anxiety disorders, said Jarvis,who is 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 mices vocalizations, he stated. Jarvis acknowledged that the findings are controversial because they contradict scientists long-held assumption about mice vocalizations. His 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. The results also contradict two recent studies suggesting mice do not match pitch or have deafness-induced vocalization changes. This is a very important study with great findings, said Kurt Hammerschmidt,an expert in vocal communication at the German Primate Center who was not involved in the study. He is cautious about some of the claims but suggested that if mice can learn vocalizations they could become a good model to study the genetic foundation of the evolution of language. Jarvis,his former graduate student Gustavo Arriaga,and a colleague from Tulane University tested male mice for vocal learning traits as part of a larger project to study speech evolution in humans. In the study,Arriaga first used gene expression markers,which lit up neurons in the motor cortex of the mices brain as they sang. Arriaga then damaged these song-specific neurons in the motor cortex and observed that the mice couldnt keep their songs on pitch or repeat them as consistently,which also happened when the mice became deaf. Arriaga 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. This direct projection from the mices forebrain to the brainstem and muscles was the biggest surprise, Jarvis said. Arriaga and Jarvis tested more than 14 mice and repeated the experiment twice to confirm the result. Jarvis added that more work does need to be done to know if mice can learn other features of vocalizations or if their learning is limited to just pitch. Our results show that mice have the five features scientists associate with vocal learning. In mice,they dont exist at the advanced levels found in humans and song-learning birds,but they also are not completely absent as commonly assumed, he said. His team is now searching mouse brains for genes specific to the brain circuits for vocal behavior. So far,these genes have only been found in songbirds and humans but,based on these results,could be in mice too,Jarvis said. The results appeared in PLOS ONE and are further described in a review article in Brain and Language.
