Scientific problem to be addressed, and why it is important The fundamental scientific problem we propose to address is to determine the basic neural andmolecular requirements for vocal learning, the behavioral substrate for spoken language. Language is one of theessential behaviors that make us human. With it, we are able to communicate complex concepts, pass onknowledge culturally, and advance human civilization. Without it due to brain damage, trauma, ordevelopmental 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 pathwaysof 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) withthe 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 brainsthat have been studied (humans, parrots, hummingbirds, and songbirds), evidence suggests that they share asimilar vocal pathway forebrain organization: a premotor or anterior vocal pathway (AVP) necessary for vocallearning, including syntax learning, and a motor or posterior vocal pathway (PVP) necessary for production oflearned vocalizations1. These forebrain pathways are not found in vocal non-learners. Yet, vocal non-learnersappear to possess similar brain pathways for learning and production of non-vocal motor behaviors. Given thesefindings, we have proposed that the fundamental difference between vocal learners and non-learners is a geneticdifference or several genetic differences that control the connection of forebrain motor learning pathways ontobrainstem motor neurons that normally control the production of innate vocalizations1. In this essay, I outlinethe 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 impacttowards understanding molecular mechanisms of vocal learning and evolution of language. Repairing thepathway in vocal learners, when damaged, would have profound impact for correcting neurological disorders ofspeech.
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