Individual vocal recognition and the effect of partial lesions to HVc on discrimination, learning, and categorization of conspecific song in adult songbirds

Among songbirds, the capacity to associate particular songs with particular singers (i.e., vocal recognition) forms the cognitive basis for more compl ex communication behaviors such as female choice and territoriality. In the present study, we combine operant conditioning techniques and excitotoxic lesions to the forebrain nucleus HVc to examine the role of this region in the discrimination, associative learning, and categorization of conspecific song. We trained adult male and female European starlings, Sturnus vulgari s, to recognize simultaneously the songs of several conspecific males. Then , using a series of transfer procedures, we demonstrate that correct recogn ition does not generalize to song bouts containing novel motifs from famili ar singers. This suggests that starlings do not make use of individually in variant source or filter characteristics for vocal recognition. We then les ioned a portion of HVc bilaterally with ibotenic acid, and exposed the bird s to a series of manipulations testing the discrimination, associative lear ning, and categorization of conspecific song. The lesions attenuated song p roduction among males, but retention of the basic recognition task (i.e., m aintenance of the discrimination) was unaffected. However, when the respons e contingencies were reversed-as a test of associative learning independent of discrimination-the initial performance and subsequent learning rate mer e negatively correlated with the size of the HVc lesions. This suggests tha t HVc plays a role in the formation of associations between a song and some referent. The results of this study are discussed in light of earlier clai ms regarding the role of HVc in the perceptual processing of conspecific so ng. (C) 2000 John Wiley & Sons, Inc.