Abstract
Among avian species that communicate by means of vocalization, vocal learning has been found to occur in three orders of birds: oscine passeriformes (songbirds), psittaciformes (parrots), and trochiliformes (hummingbirds). Male songbirds learn species-specific songs by matching their own vocalization to a memorized tutor's song using auditory feedback during a sensitive period in juveniles. Recent reports including our studies indicate that auditory feedback is also necessary for maintaining the stability of adult song. However, much less is known about the role of auditory feedback in adult since effects of auditory deprivation are different among species. In this review article, we first introduce ethological studies in which we compared altered song pattern induced by deafening among different species. We then present our data that show changes appearing in song control system in adult brain during deafening-induced song alteration, and what may induce these changes. In addition, we introduce recent topics on adult neurogenesis, which are also considered to relate with adult song plasticity. Based on these studies, we discuss the possible function of auditory feedback that regulates adult song maintenance and plasticity.
