Lesions to the medial preoptic nucleus affect immediate early gene immunolabeling in brain regions involved in song control and social behavior in male European starlings

The medial preoptic nucleus (POM) is a brain region outside of the song control system of songbirds. It has been implicated in song production, sexual motivation, and the integration of both sensory and hormonal information with appropriate behavioral responses. The POM is well positioned neuroanatomically to interact with multiple regions involved in song, social behavior, and motivation. However, little is known about the brain regions with which the POM directly or indirectly communicates to influence song. To gain insight into the neuronal circuits normally activated in association with POM activity during male song, we compared activity within multiple brain regions using immunolabeling for protein products of immediate early genes (IEGs) zenk (aka egr-1) and c-fos (indirect markers of neuronal activity) in sham and POM-lesioned male European starlings (Sturnus vulgaris). As compared to sham lesions, POM lesions disrupted song and interest in a nest box, and females responded less to POM-lesioned males. POM lesions reduced numbers of IEG-labeled cells and disrupted correlations between numbers of IEG-labeled cells and song within several song control, limbic, hypothalamic and midbrain regions. These results are consistent with the possibility that the POM integrates activity among nuclei involved in song control, social behavior and motivational state that work in concert to promote sexually motivated communication.