Studies in songbird communication: Neurophysiology of the interaction between the auditory and vocal systems in males and mate choice behaviour in females

Communication is an essential part of life in the animal kingdom. The songbird communication system is perhaps the best understood system as studies have revealed a detailed skeleton of the ontogeny of male singing behaviour and the brain structures specialized for this behaviour (the song system). One of the most interesting properties of neurons within the song system is their tendency to respond more strongly to playback of the bird's own song than to other conspecific song. Areas presynaptic to the song system do not show this preference as a whole. In the first study of this dissertation, I sought to investigate the possibility that there exists a subset of cells within the auditory system that is functionally connected with the song system and shows a preference for responding to the bird's own song. I addressed this question using double electrode recoding in anesthetised zebra finches and running a cross correlation analysis on the obtained spikes. The results show that there is a subset of cells that is functionally connected to the song system, but that this subset does not show a higher degree of selectivity for the bird's own song than cells outside of the subset. This suggests that the extreme specificity found in song system neurons arises either through a more indirect pathway or through the complex convergence of properties from neurons in several different regions.;It is known that males use song to attract female mates and that females are attracted to males that sing more complex songs. In the second study, I focused on the receiver in the songbird system, the female, and studied the influence of early auditory experience on mate choice behaviour using sexual displays as the primary assay of choice. I found that females reared with a father who sings abnormal song did not make the same mate choices in later life as those that were raised in a social context, with a father who sings normal song. This suggests that the female preference for complexity can be altered if the "tutor" male sings a simple song throughout the female's development.