How Stuttering Songbirds Could Cure It in People

An estimated 7.5 million Americans show some difficulty in speaking, ranging from light stutters to severe language impairment, according to the National Institute on Deafness and Other Communication Disorders. Some can overcome the impediment through speech therapy, but many will live their whole lives with the disorder. But a recent study of birds may offer up a new model for researching and treating these problems.

Scientists at Duke University spent six years studying the brain regions of vocal-learning birds—species such as songbirds and parrots that can learn to produce vocalizations by imitating sounds that they hear—and cross-referencing them with the human brain. They found that the birds exhibit "tens to hundreds" of genes related to vocalization that seem to match those in humans, including 50 genes from one brain region that appear to be responsible for vocal-learning abilities in both humans and birds.

The study, published in December 2014 in the journal Science, suggests that songbirds and other vocal-learning animals could be used as potential models for examining the internal circuitry and brain regions associated with speech production and motor skills. "A challenge in the area of both motor and speech disorders is the development of appropriate animal models," says study co-author Andreas Pfenning, now a postdoctoral associate at MIT who specializes in genomics research. He says no mammals "can do a good job of mimicking—and acting as proper models for studying—vocalizations." Songbirds could be the solution. It turns out humans are a lot like these birds when it comes to making noises. For example, we both babble when learning vocalization skills at a young age—and both species can develop stuttering disorders.

"The songbird," says Pfenning, "could be used to work out some of the underlying mechanisms at the level of genes, circuits and how they relate to each other," and thereby, aid in the search for future treatments for human stutterers.

Nan Bernstein Ratner, a fellow with the American Speech-Language-Hearing Association who was not part of the study, says the study "is exciting in a basic science sense, because it will inform what systems may be impaired when we see individuals with certain speech problems." However, she adds, "treatment is certainly a distant extension of this work and may or may not emerge from this line of work."

Either way, the study does shine light on our origins as a social species, supporting previous research that links people and vocal-learning birds to a common ancestor from over 310 million years ago. "Vocal learning, and speech, is something that defines us as a species," says Pfenning. "This project gives us insight into how that ability evolved."