By singing mice, scientists find a clue to our own quick conversations

Researchers from New York University's Faculty of Medicine and the University of Texas at Austin studied mouse songs from Costa Rica's cloud forests and identified a brain circuit that could allow for rapid exchange between humans. This idea, published online today in the journal Science, could help researchers better understand the causes of speech disorders and point the way forward for new treatments.

When two of Alston 's singing mice meet, one on her own turf and the other from outside, they sing a kind of duet, in the image of two performers opera who claim their right to the territory or compete to attract the attention of a young girl. But the stranger, called a rookie, only starts to sing when the resident has finished his song, then stops immediately if the resident restarts.

"The recruit states that he is there and that he will compete with the resident," said Steven Phelps, co-author of the study, professor of Integrative Biology and director of the Center for Brain, Behavior and Evolution at UT Austin. "The resident says I'm already here and I plan to stay."

This rapid alternation, called taking turns of voice, is as if two humans were in conversation. Standard laboratory mice do not seem to have this type of voice exchanges. Thus, the new study represents a new mammalian model to examine the brain mechanisms behind the sub-second accuracy of vocal speech.

"Neuroscientists have traditionally focused on a small number of model organisms to better understand the human brain," said Phelps, pioneering the study of mouse-singers, a model of neuroscience communication and behavior in 2002. "This study shows that scientists can get new interesting information by tapping into the enormous wealth of natural diversity among animals."

The study found that with areas of the brain that require the muscles to create notes, separate circuits in the motor cortex allow quick starts and stops that form a conversation between the vocal partners.

"Our work directly demonstrates that a region of the brain called the motor cortex is necessary for these mice and humans to interact vocally," said Michael Long, lead author of the study, an associate professor of neuroscience at the NYU School of Medicine.

"By separating the circuits of production and control of sound, evolution has endowed the brains of mouse singers with the strict vocal control also observed in cricket exchanges, bird duets and, possibly, in human discussions", added the co-first author, Arkarup Banerjee, postdoctoral researcher. in the laboratory of Long.

Despite the omnipresence of vocal exchanges in the natural world, Banerjee said, there was previously no appropriate mammalian model in neuroscience for their study.

To go forward, researchers are already using their mouse model to guide the associated exploration of speech circuits in the human brain. By understanding the activity that helps engage the conversation between two brains, they can research the processes that deteriorate when the disease interferes with communication, potentially stimulating the development of new treatments for many disorders.

"We need to understand how our brain generates verbal responses with nearly a hundred muscles if we want to design new treatments for the many Americans for whom this process has failed, often because of diseases like autism or trauma such as stroke ". Long.

Previous work by Phelps and his team at UT Austin has shown that in addition to attracting mates and repelling rival males of the same species, calls from males of a species of mice singing repel males of a similar but smaller species.

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Alongside Long, Phelps and Banerjee, Daniel Okobi Jr. and Andrew Matheson were authors of the NYU Neuroscience Institute and the Department of Otolaryngology's study of neuroscience. Faculty of Medicine at this university.

This research was funded by the New York Stem Cell Foundation, the Simons Foundation's Society of Fellows and the Simons Collaboration on the Global Brain.

This release is based in part on a press release issued by the NYU School of Medicine.