Molecular Mapping of Movement-Associated Areas in the Avian Brain: A Motor Theory for Vocal Learning Origin (Feenders et al)
Certain groups of birds, like humans and a small number of other mammalian species, are capable of learning to use their voices to imitate what they hear. While other studies have determined genetic expression that is unique to this trait, as well as unique regions of the brain that are not present in species that are vocal but not vocal learners, the origin of these brain regions has not been well understood. The authors of this study propose that a major constraint on the evolution of vocal learning in the avian orders that feature this capability is a set of seven brain regions that correlate with specific types of movement when active. The authors suggest that not only do the movement regions of the bird brains have a feed-forward relationship with the vocal regions, but also that the vocal regions have a feed-back relationship with the movement regions. The study wraps up by suggesting a theory that in distantly related animal species the brain-based capacity for vocal learning evolved from specialized brain regions that control movement and perhaps even movement-based learning. This theory requires significant experimentation for validation, but has the potential to provide a powerful explanatory mechanism for the evolution of vocal learning not just in distantly-related bird species, but also in distantly-related mammalian species, as well as between birds and mammals. Furthermore, the authors note the gestural precursors to spoken language in early human development and the benefits that formalization of these gestures (sign language) can provide to learning to speak. In summary, this study provides further neuroscientific support for cognitive resources and suggests, specifically, that movement capacity serves as a resource for complex cognitive development.