Multiple Disciplinary Collaborative Research: Evolution of Brain Structures for Vocal Learning in Birds

Duke University, Durham NC

Investigators

Abstract

Jarvis. Lay Abstract Vocal learning is the process by which young animals learn to imitate the vocal sounds made by their parents or a tutor. This rare trait has only been found in humans, whales, dolphins, bats and 3 groups of birds (hummingbirds, parrots and songbirds). The goal of this project is to identify and characterize the brain areas that control vocal communication in hummingbirds, as well as test whether the brains of birds that do not have vocal learning, such as chicken and pigeons, contain similar structures. The main method used is analysis of a gene that is expressed in the brain when neuronal cells fire. Utilizing a molecular technique called in situ hybridization, one can determine the exact brain cells that are involved in the perception and production of vocalizations. By comparing hearing and vocalizing animals, one can then generate high-resolution maps of brain areas that control the production of learned vocalizations. Language acquisition, both in terms of speech production and semantics, is a fundamental aspect of the human experience and depends on vocal learning. Why is it though that so few animals have vocal learning? Do only these animals have the necessary brain structures and connections? If so, what are these structures, and how did they arise during evolution? By addressing such questions, this study may help reveal what are the brain mechanisms required for vocal learning, and potentially help understand how humans learn speech. The results should also provide a framework for studying the neurobiology of learned vocal communication in other animal groups. If the evolution of vocal learning is under strong epigenetic constraints, it is possible that humans, cetaceans and bats have also evolved similar brain structures. Alternatively, brain areas for vocal learning may have evolved as a specialization of structures present in a vocal non-learning ancestor. Results from this project are expected to throw considerable light on these questions.