Neuronal activation related to auditory perception in the brain of a non-songbird, the ring dove

Abstract

In songbirds, parrots, and hummingbirds, which need to learn their songs, exposure to conspecific song leads to increased expression of the immediate early gene (IEG) ZENK in a number of forebrain regions, including the caudomedial nidopallium (NCM) and the caudomedial mesopallium (CMM). Here we investigated the pattern of IEG expression in response to auditory stimulation in the brain of the ring dove (Streptopelia risoria), a non-songbird that does not need to learn its vocalizations. Ring dove males were exposed to conspecific vocalizations (coos), to heterospecific vocalizations (zebra finch song) or they were kept in silence. IEG expression was investigated by means of immunocytochemical analysis of the distribution of the ZENK protein product Zenk. In all three groups there was Zenk expression in several forebrain regions including the NCM and the CMM, similar to earlier findings in song-learning species. Quantitative analysis of the NCM, the CMM, and the hippocampus revealed significantly greater Zenk expression in birds exposed to conspecific vocalizations than in birds kept in silence, in the CMM only. These results show that there is substantial Zenk expression in the forebrain of a non-song-learning bird, comparable to that in avian song-learning taxa. These findings suggest that there is IEG expression specific to conspecific auditory stimulation in the CMM in both songbirds and non-songbirds.