Scientific problem to be addressed, and why it is important The fundamental scientific problem we propose to address is to determine the basic neural and molecular requirements for vocal learning, the behavioral substrate for spoken language. Language is one of the essential behaviors that make us human. With it, we are able to communicate complex concepts, pass on knowledge culturally, and advance human civilization. Without it ? due to brain damage, trauma, or developmental diseases - we live a life of impoverished social communication and life dependency on others. Studying this fundamental problem requires that we compare the vocal behavior and associated brain pathways of the few rare groups that have vocal learning - four groups of distantly related mammals (humans, cetaceans, elephants, and bats) and three groups of distantly related birds (parrots, hummingbirds, and songbirds) ? with the vast majority of species that do not have it - non-human primates, rodents, suboscine songbirds, pigeons, chickens, etc.1,2. Remarkably, although vocal learners are distantly related to each other, of those whose brains that have been studied (humans, parrots, hummingbirds, and songbirds), evidence suggests that they share a similar vocal pathway forebrain organization: a premotor or anterior vocal pathway (AVP) necessary for vocal learning, including syntax learning, and a motor or posterior vocal pathway (PVP) necessary for production of learned vocalizations1. These forebrain pathways are not found in vocal non-learners. Yet, vocal non-learners appear to possess similar brain pathways for learning and production of non-vocal motor behaviors. Given these findings, we have proposed that the fundamental difference between vocal learners and non-learners is a genetic difference or several genetic differences that control the connection of forebrain motor learning pathways onto brainstem motor neurons that normally control the production of innate vocalizations1. In this essay, I outline the following proposal for testing this novel idea: 1. Discover molecular differences in the motor learning pathways between vocal learners and non-learners. 2. Manipulate their network connectivity by developing novel gene manipulation tools. 3. Use these tools to modify vocal nuclei connectivity and thus vocal behavior of a vocal non-learner, potentially allowing other species to modify and imitate sounds and allowing correction of damaged vocal learning brain pathways in vocal learners. Inducing such connectivity and behavioral changes in vocal non-learners would have profound impact towards understanding molecular mechanisms of vocal learning and evolution of language. Repairing the pathway in vocal learners, when damaged, would have profound impact for correcting neurological disorders of speech.
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