When Mice Serenade the Forest…
Until now, you might have been forgiven for thinking that singing mice were merely the product of Disney’s prolific imagination. Not anymore! Although it wasn’t classically trained by a modern P.T. Barnum, the singing mouse is a reality.
The undergrowth of Central American cloud forests plays host to a species of musical mice that trills songs and duets with one another.
Starring the Alston Brown Mice
The Alston’s singing mouse (Scotinomys teguina) is famous for its unique vocalisations, characterised by singing bouts in both the sonic and ultrasonic range.
Because of their length and complexity, these vocalisations have been described as “song”.
Although ultrasonic vocalisations have been demonstrated in numerous rodent species, few display vocalising bouts as continuous and stereotyped as S. teguina.
Both males and females produce theses vocalisations that are thought to be an important component of their communication behaviour.
Costa Rican Sing Off
According to Michael Long, a neuroscientist at New York University’s School of Medicine, the study of this “quirky animal” from the cloud forest of Costa Rica could bring a brand new insight into the rapid give-and-take in people’s conversations.
When two male singing mice create a rapid-fire duet, the timing of their songs is controlled by a brain area called the orofacial motor cortex.
The research reveals how the brain of the charismatic little creatures orchestrate these rapid-fire duets.
The results, published in Science, show that the brains of singing mice split up the musical work.
What Goes On In The Brain Of The Singing Mouse
The neuroscientists describe an orofacial motor cortex (OMC) that mediates rapid transition from the motor cortex to the vocal motor apparatus and facilitates rapid vocal interactions.
One brain system is thought to control the contents of the songs. Another part, the OMC orchestrates the split-second timing needed for the mouse duets, Long and his colleagues found.
The brain is an incredibly complex organ. For example, the tiny mouse brain contains over 86 million neurons, each with over 1,000 different connections. It seems a lot, until you consider that the human brain has more than 86 billions of neurons!
In the present case, one brain system directs the patterns of notes that make up songs, while another coordinates duets with another mouse, which are carried out with split-second precision.
Give and Take
The ability to “take turns” is a hallmark of social interaction among animals.
From duetting birds to frogs, this trait occurs in many different species, and is a notable part of human speech.
Such rapid response requires a complex cascade of sensory and motor actions that has been difficult to characterise.
Okobi et al. (2019) examines turn-taking in tropical singing mice, in which males interrupt, and alter, each other’s songs.
In the wild, these duets are thought to attract mates and stake out territory.
Of course, the mice are also loud, particularly in the confines of a lab: “They’re very vocal,” Pasch says.
“Once an animal calls, it’s like a symphony that goes off.”
When the research team cooled the mice’s OMC, slowing those nerve cells’ activity, the songs grew longer, suggesting that the brain region normally controls song timing.
And when the researchers used a drug to silence the OMC, the mice had trouble singing duets in response to another mouse’s call.
“In a very clear and convincing way, they show that this structure is involved in this behaviour,” says neurobiologist Steffen Hage of the University of Tübingen in Germany who wrote an accompanying commentary in Science.
The singing mice’s OMC may not align exactly with the brain areas used to pace human chatter.
Still, the results may ultimately yield clues to human conversations, which often proceed at similarly fast clips. That pursuit might ultimately lead to therapies for disorders that affect communication, such as strokes and autism, Long says.
The results also highlight the benefits of studying a variety of animals in creative ways.
As we put microphones up to ever more species, we are only just beginning to hear a lot of them using their voices…