Abstracts from the Harvard Undergraduate OpenBio Laboratory Student Research Institute 2025

Although much remains unknown about the development of neural circuits that support fine motor skills like speech, songbirds offer a powerful model for studying the formation of motor circuits and exploring what factors drive the emergence of complex vocal behaviors in humans. Multiple peer-reviewed sources were selected based on relevance, research quality, and focus and were synthesized to provide a balanced and unbiased overview of current comparative or developmental understandings of motor circuitry. The analysis revealed that neurons within the songbird HVC and RA share molecular and functional similarities with layers of the mammalian neocortex, as well as with regions of the non-neocortical ventral pallium. This evidence suggests that songbirds and mammals likely underwent convergent evolution that gave rise to their vocal motor circuits, including the independent development of specialized gene expression for complex vocal behaviors. However, until recently, experiments have been limited in their ability to resolve molecular differences between cell populations that give rise to the circuitry architecture observed in complex vocal learning species. We present advancements that contribute to a deeper understanding of analogous physiological and molecular function and highlight a gap in knowledge surrounding neuron diversification and neural circuit evolution.