A recent research has found that songbirds have a distinct right-brain response to the sound of songs, and can provide clues to human speech disorders.
Researchers at the Methodist Neurological Institute (NI) in Houston and Weill Cornell Medical College in New York City used functional MRI to find out the results.
The study has created base for a foundational study for future research on songbird models of speech disorders such as stuttering, as reported in Proceedings of the National Academy of Sciences U.S.A.
This is the first functional MRI study to agree on how vocal sounds are represented within the brain of an awake zebra finch, a well-studied animal model of vocal learning. Because of many similarities between birdsong and human speech, this research could lead to an improved understanding of the cause of stuttering and other speech problems.
By using specifically-tailored high-resolution fMRI in awake, gently sedated zebra finches, scientists were able to look at the activity in the entire avian brain during song stimulation.
"While we found that both sides of the brain were activated by sounds in the songbirds, our research showed that the right side of their brains discriminated sounds better. If we can link what we find in birds to what we already know about human brains, then we could better understand the causes of speech disorders and, in the long-run, be able to provide treatments to patients," said Santosh A. Helekar, M.D., Ph.D., lead author of the paper. Helekar is associate research professor of neuroscience at the Methodist NI and Weill Cornell.
Using the blood oxygenation level-dependent (BOLD) fMRI method, researchers observed brain response patterns in 16 adult zebra finches during playback of the birds' own song, their tutor's song, an unfamiliar zebra finch's song, and a synthetic sound of a single frequency.
The songbirds' own song caused a stronger response in the auditory areas of the brain. On the whole, findings suggest that vocal sounds may be better represented on the right side of the brain in these songbirds.
"We don't know exactly what goes wrong with the human brain when a patient stutters or has a particular speech problem. But, if we can understand the neurobiology of the brain of this animal model and how sounds are processed by birds that produce normal and variant songs, then we may be able to translate these findings into treatments for patients with disorders such as stuttering and verbal dyspraxia," said Henning U. Voss, Ph.D., first author on the PNAS paper and assistant professor of physics in radiology at Citigroup Biomedical Imaging Center of Weill Cornell Medical College.
The vocal learning process in the zebra finch offers a model system to study the neural and behavioral mechanisms by which humans learn to make sounds. Songbirds such as zebra finches have specialized areas of their brains dedicated to communication. That is why they have been used as animal models to study speech disorders, such as stuttering. It is estimated that more than 3 million Americans stutter.
The research was supported by grants from the National Institutes of Health, The Methodist Hospital Research Institute and Weill Cornell Medical College, and Deutsche Forschungsgemeinschaft Research Center Matheon.