Researchers have found that male mice trill startlingly intricate songs to beguile female mice-in much the same way as birds do.
It's no surprise that mice sing-that much has been known for decades. Not that people can hear the songs. The mice voice 'ultrasonic vocalizations' (USVs), sounds that are too high-pitched for our ears to decipher.
From the first utterances made by a mouse pup to its mother, and through the adult years, the sounds become more complicated. Researchers are trying to understand the songs and their many variations. Mice may not have as wide a range for tweaking their songs as birds do, but they may help us better grasp some elements of vocal communication and communication disorders, according co-corresponding author Erich Jarvis, PhD, associate professor of neurobiology, Duke University and a Howard Hughes Medical Institute Investigator. The Erich Jarvis Lab investigates the complexities of these utterances, aiming to help us more thoroughly comprehend the processes involved in making songs and to devise a model to examine diseases that impact vocal communication.
The team found that no only do males sing more involved songs, but they dial up the volume when they catch a whiff of a female mouse's urine, as long as she's out of sight. When the males spot the females nearby, the songs are longer, but less complex-and sung for the female's benefit.
"We think this has something to do with the complex song being like a calling song, and then when he sees the female, he switches to a simpler song in order to save energy to chase and try to court her at the same time," says Jarvis, who's also a member of the Duke Institute for Brain Sciences.
"It was surprising to me how much change occurs to these songs in different social contexts, when the songs are thought to be innate," Jarvis says. "It is clear that the mouse's ability to vocalize is a lot more limited than a songbird's or human's, and yet it's remarkable that we can find these differences in song complexity."
The majority of female mice studied showed a preference for listening to the complex songs (transmitted via speakers), and their differing reactions to dissimilar songs suggests the songs are laced with meanings, according to Jonathan Chabout, PhD, Duke postdoctoral fellow.
The team plans to look into the role of different genes and brain areas in the songs.
Finding out to what degree the mice can learn to modify their songs, as opposed to choosing among fixed patterns, may yield useful answers in the study of autism spectrum disorders, distinguished in part by deficits in social communication and, probably, in brain circuits that control learned behavior, Jarvis says. "That's why we and other scientists from all over the globe are studying mice to test the limits of vocal learning and plasticity."
The researchers have uploaded their recordings to "MouseTube," an expanding repository created by scientists at the Institute Pasteur, Paris, which will likely contain USVs from around the globe, across different strains and in different experimental contexts. (The researchers used a specific mouse for this study that's known for its vocal abilities.)
"We hope to help other researchers study USVs," Chabout says. "And we bring a new way of looking at them dynamically."
Mouse Song Analyzer v1.3, the new method, and an Excel-based song analysis tool, are freely available on the Jarvis Lab website.
The study, "Male mice song syntax depends on social contexts and influences female preferences," is available in the Frontiers of Behavioral Neuroscience.
Judy O'Rourke worked as a newspaper reporter before becoming chief editor of Clinical Lab Products magazine. As a freelance writer today, she is interested in finding the story behind the latest developments in medicine and science, and in learning what lies ahead.
