Neurophysiological coordination of duet singing

Cooperation is critical for survival and reproduction in many animal species. Coordination of behavior for cooperative performances often relies on linkages mediated by sensory cues exchanged between participants. How neurophysiological responses to sensory information affect motor programs to coordinate behavior between individuals is not known. We investigated how plain-tailed wrens (Pheugopedius euophrys) use acoustic feedback to coordinate extraordinary duet performances in which females and males rapidly take turns singing. We made simultaneous neurophysiological recordings in a song control area 'HVC' in pairs of singing wrens at a field site in Ecuador. HVC is a premotor area that integrates auditory feedback and is necessary for song production. We found that spiking activity of HVC neurons in each sex increased for production of its own syllables. As acoustic feedback is critical for the coordination of duet performances, we expected neurons to respond to singing cues from the partner bird. Surprisingly, these `heterogenous' cues resulted in decreases in HVC activity during duet singing, potentially coordinating the pattern generating circuit in HVC in each bird through inhibition. To examine the role of acoustic feedback in the absence of motor activity, we recorded responses of HVC neurons to playbacks in anesthetized wrens. Neurons showed significant excitatory responses to heterogenous cues within duets. These data suggest that HVC integrates information across partners during duets, and that rapid turn-taking is mediated, in part, by inhibition from heterogenous cues.