What Can Singing Mice Teach Us About Human Conversation?

The Context: The brain activity that enables the rapid back-and-forth of human conversation is likely disrupted in diseases or disorders that interfere with normal communication such as autism or stroke. However, this process is not well understood.

The Study: Researchers led by NYSCF – Robertson Neuroscience Investigator Alumnus and NYU Associate Professor in the Departments of Otolaryngology—Head and Neck Surgery and Neuroscience and Physiology Dr. Michael Long report in Science that they have uncovered a brain circuit in a certain species of mice known for communicating through extended chirps that could give rise to the intricacies of conversation.

The Importance: This study sheds light on the on the process of complex communication, demonstrates for the first time that mammals other than primates use parts of their brain cortex to control sounds, and will inform future studies of human speech disorders.

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“Singing mice” might sound like a characteristic of a Disney movie, but according to new research from NYSCF – Robertson Neuroscience Investigator Alumnus Dr. Michael Long, these special creatures are giving us insight into the underpinnings of complex conversation.

The mice—a species called “Alston’s singing mouse” native to the cloud forests of Costa Rica—are known for producing unique songs comprised of high-pitched, extended chirps. In a new study published in Science, Dr. Long (an Associate Professor of Otolaryngology-Head and Neck Surgery and Neuroscience and Physiology at NYU Medical School) and his colleagues examined the neural basis of communication in the singing mice and identified a group of brain cells that appear to be responsible for the back-and-forth of conversation. The findings shed light on the process of complex communication, demonstrate for the first time that mammals other than primates use parts of their brain cortex to control sounds, and can inform our understanding of speech problems in disorders such as autism.

When Dr. Long’s team first began studying singing mice, they noticed that the way in which the mice produced their songs showed similarities to human conversations. Specifically, when the mice spoke to each other, they took turns, just like humans do. This challenged the belief that animals do not engage in conversation, suggesting instead that the singing mice could serve as a useful model for studying complex communication.

The researchers then examined how singing was affected when the mice had different sections of their brains cooled down (a manipulation that causes neurons to slow their activity). They identified a certain portion of the mouse cortex that when cooled, caused the mice to sing extended songs.

The team then injected nerve-blocking drugs into this part of the cortex and played a recording of another male mouse’s song. The mice with the injections were slow to respond, and often failed to sing back altogether.

The results led the team to believe that this brain region acts as the command center for conversation. Dr. Long believes that a similar circuit likely exists in humans, and that both the human and singing mouse circuits could be influenced by the same genes.

“Our work directly demonstrates that a brain region called the motor cortex is needed for both these mice and for humans to vocally interact,” said Dr. Long in a press release from NYU.

Next, Dr. Long plans to use the mouse model to inform studies of speech circuits in the human brain, looking specifically at how the circuits may be altered in diseases and disorders that interfere with communication.

“We need to understand how our brains generate verbal replies instantly using nearly a hundred muscles if we are to design new treatments for the many Americans for whom this process has failed, often because of diseases such as autism or traumatic events, like stroke.”

Read more in:

The New York Times

Forbes

Smithsonian.com

Original research article:

Motor cortical control of vocal interaction in neotropical singing mice.

Daniel E. Okobi Jr., Arkarup Banerjee, Andrew M. M. Matheson, Steven M. Phelps, Michael A. Long. Science, 2019 DOI: 10.1126/science.aau9480 

Photo credit: NYU School of Medicine