Development of a Mammalian Model of Vocal Learning

Washington State University, Pullman WA

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Abstract

PROJECT SUMMARY Imagine a future where no child is disadvantaged in school because of a speech impediment or language disorder. Currently, five percent of children enter first grade with some form of speech disorder that impairs their ability to learn. Finding ways to reduce the prevalence of communication disorders would impact millions of children. Children learn to speak by listening to their caregivers and imitating the sounds they hear. Unfortunately, this process of vocal learning can be disrupted by a number of genetic or other disorders of hearing. To develop better treatments, or to reduce disorders related to vocal learning, the neural mechanisms underlying vocal learning need to be understood. For over 50 years, songbirds have been the laboratory model of choice to study vocal learning because they share similarities to humans in how they learn their songs. While much has been learned about the circuitry for vocal learning in songbirds, studies in songbirds are not as translational to humans as is required to determine the neural mechanisms underlying human vocal learning and associated disorders. Thus, there is a need for an experimentally accessible mammalian model of vocal learning. The objective of this proposal is to determine whether baby bats learn to produce their vocalizations by imitating the vocalizations of adult bats. To test for vocal learning in bats, conductive hearing loss will be induced in baby bats immediately after birth because juvenile hearing loss is the manipulation that most dramatically disrupts adult song in birds and speech in humans. Bats will be fitted with earplugs that profoundly reduce hearing sensitivity. Aim 1 will determine whether bats require auditory feedback to produce normal vocalizations. Aim 2 will determine whether bats use imitation to produce vocalizations. This innovative project will determine conclusively whether bats are imitative vocal learners. The project has high potential impact because it could identify bats as an experimentally accessible mammal to directly study the neural mechanisms underlying human vocal learning and associated disorders. This would be a significant leap forward in ultimately providing better therapies to reduce the impact of communication disorders on children and adults.