This project investigated the neurobiological substrates of vocal turn-taking, a complex communicative behavior requiring precise sensorimotor integration and flexible vocal responses. Utilizing the counter-singing behavior of nightingales as a model system, we aimed to elucidate the neural mechanisms underlying rapid auditory-motor mapping and context-dependent vocal adjustments.
Behavioral analyses of wild nightingales engaged in vocal interactions with playbacks revealed the capacity for instantaneous and accurate pitch imitation across their vocal repertoire suggesting a highly efficient auditory-vocal transformation pathway. Furthermore, investigation of territorial vocal exchanges demonstrated dynamic modulation of song timing and spectral features contingent upon rival identity, underscoring complex auditory processing during social communication. To probe the neural correlates of these behaviors, electrophysiological recordings were conducted in the premotor nucleus of songbirds involved in song learning and production. Complementary studies in zebra finches focused on the role of inhibitory circuits within the premotor nucleus. Selective manipulation of inhibitory interneurons in adult zebra finches, beyond the critical period for song learning, resulted in the reopening of a latent window of motor plasticity, enabling the acquisition of novel vocal syllables upon exposure to new auditory. This demonstrates a critical role for inhibitory mechanisms in regulating vocal learning and potentially in shaping the adaptive vocal responses observed during vocal turn-taking. Additionally, we found that inhibition within the premotor nucleus regulates the timing of vocal output during vocal turn taking
Collectively, these findings provide insights into the neural circuits and mechanisms underlying vocal turn-taking, highlighting the importance of rapid auditory-motor integration, context-dependent processing, and the regulatory role of inhibitory microcircuits in shaping vocal behavior.
