Development of neural selectivity for birdsong during vocal learning

Juvenile white-crowned sparrows learn to sing by first memorizing an adult's song and then progressively matching their vocalizations to this model during plastic song. Previous studies have shown that neurons in the song-system nucleus HVC of adult sparrows respond preferentially to a bird's own song. In this study, the auditory selectivity of HVC neurons in subadult birds was examined. In young, nonsinging birds who had been song tutored, these cells responded to song stimuli, and at some recording sites had distinct preferences for one song or another. As a population, however, HVC neurons in these birds showed no preference for familiar song. They were no more likely to prefer normal tutor song to reversed tutor song or to the song of another white-crowned subspecies. By contrast, in birds producing plastic song, HVC neurons were selective for the bird's own songs, even in preference to their tutor song. Therefore, during song learning the response properties of HVC neurons appear to be dynamically modified, perhaps by auditory feedback from the bird's own vocalizations. The emergence of song selectivity during plastic song may be significant both for song learning and for song perception in adult birds.