Lesions to the medial preoptic area affect singing in the male European starling (Sturnus vulgaris)

The aromatization of testosterone (T) in the medial preoptic nucleus (POM) is known to regulate male courtship and sexual behaviors expressed prior to , and in anticipation of, copulation. Singing in male European starlings is used to attract mates prior to physical sexual contact, suggesting that th e POM might be involved. The present study was performed to examine the eff ects of lesions targeting the POM on singing and courtship behavior in repr oductively active male starlings. A significant decrease in song output and the gathering of green nest materials was observed in males with lesions t o the POM compared to males with damage to brain areas outside of the POM. Lesions did not affect: a male's tendency to remain near a female or to occ upy a nestbox, suggesting that the effects of POM lesions were specific to courtship behaviors. Behavioral differences were not related to testis mass or volume, and GnRH immunoreactivity was observed within the hypothalamus and median eminence for each male, suggesting that the effects al:POM lesio ns were related specifically to POM involvement in song expression rather t han to a disruption of the GnRH axis. These results suggest a general role for the POM In the expression of behaviors related to sexual arousal or ant icipation, including song. (C) 1999 Academic Press.