An anterior forebrain pathway in parrots is necessary for individual signatures of learned vocalizations

Parrots have enormous vocal imitation capacities and produce individually unique vocal signatures. Like songbirds, parrots have a nucleated neural song system, but because the two sister groups diverged over 50 million years ago it remains unknown if the song systems operate according to similar principles. Here we established a neuroscience-compatible call-and-response behavioral paradigm to elicit learned contact calls in budgerigars ( Melopsittacus undulatus ). Using variational autoencoder-based machine learning methods, we show that contact calls within affiliated groups converge but that individuals maintain unique acoustic features, or vocal signatures, even after call convergence. Next, we transiently and reversibly inactivated the outputs of the anterior forebrain pathway (AFP) as animals engaged in call-and-response interactions. Contact call pitch modulation, stereotypy and acoustic structure were dramatically degraded, resulting in the loss of individually unique features of the vocal signature. These results are in stark contrast to results from songbirds, where AFP inactivations with identical methods have the opposite result of increasing the stereotypy of learned vocalizations and retaining acoustic structure. Together, our results show that the anterior pathways of parrots and songbirds have different functional organization and that parrot frontal cortical circuits are necessary for individually unique features of vocal communication. ### Competing Interest Statement The authors have declared no competing interest.