NSF Award
1456302
Hummingbirds, songbirds and parrots learn their vocalizations from adults, just like human infants learn to speak by imitating their parents' speech. This capacity provides the basis for how humans acquire speech and language, yet how the brain achieves this goal is unknown. Using an array of powerful techniques, this collaborative project will examine the anatomical, electrical, and molecular properties of brain circuits that control vocalizations in hummingbirds and songbirds, comparing them with each other and with prior human studies. Understanding how these different organisms evolved brain circuits to accomplish similar goals will reveal insights into fundamental properties of vocal learning systems. Traditional lab animals cannot be used as they lack vocal learning; hence, the use of vocal learner birds is critical. The project will provide training in multiple research techniques to high school, undergraduate, and graduate students, emphasizing underrepresented groups. It will also promote broad dissemination of findings and outreach activities, related to both scientific and conservation efforts. The project is also integrated with an International Consortium (funded by the Brazilian Government) for cataloguing and characterizing the diversity of tropical birds, including integration of Museum collections, generation of genome sequences, and examination of brain specimens relevant to the evolution of vocal learning. These activities will enable interactions between US and Brazilian faculty and students, while promoting training in molecular and histological methods through site visits, field trips, and workshops.<br/><br/>The vocal control system of songbirds is critical for song production and learning, and is well characterized anatomically, electrophysiologically, and molecularly. However, knowledge of the analogous areas in other avian vocal learners is limited. Recent phylogenomics efforts reveal that hummingbirds evolved vocal learning independently of songbirds; thus, comparing their vocal control systems will reveal convergently evolved features that may be fundamentally required for this trait. The investigators will use tract-tracing to determine how vocal control areas are connected in hummingbirds, in vitro electrophysiological recordings to determine intrinsic neuronal properties of vocal areas in hummingbirds and songbirds, and in situ hybridization to identify molecular markers of vocal nuclei. Evidence of shared anatomical, physiological and molecular specializations will point to convergent features representing possible universal properties of vocal learning systems that may also be shared with humans. Alternatively, differences would suggest that multiple circuit and cellular/molecular architectures can subserve vocal learning. Outcomes will provide novel clues as to evolutionary origins and constraints of vocal learning and associated pathways, leading to insights into fundamental requirements of vocal learning.
