Songbirds, Grandmothers, Templates: a Neuroethological Approach

Citation

Margoliash, Daniel (1984) Songbirds, Grandmothers, Templates: a Neuroethological Approach. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2yhr-5t19. https://resolver.caltech.edu/CaltechTHESIS:11282018-101712728

Abstract

Songbirds such as the white-crowned sparrow memorize the song of conspecific adults during a critical period early in life, and later in life develop song by utilizing auditory feedback. Neurons in one of the telencephalic nuclei controlling song have recently been shown to respond to acoustic stimuli. I investigated the auditory response properties of units in this nucleus using a technique that permitted great flexibility in manipulating complex stimuli such as song. A few of the units exhibited considerable selectivity for the individual's own song. In wild-caught birds, song specific units exhibited intra-dialect selectivity. In those birds that sang abnormal songs due to laboratory manipulation of song exposure during the critical period for song learning, units were selective for the abnormal songs. By systematic modification of a song, and by construction of complex synthetic sounds mimicking song, the acoustic parameters responsible for the response selectivity were identified. Song specific units responded to sequences of two song parts, but not to the parts in isolation. Modification of the frequencies of either part of the sequence, or increasing the interval between the parts, varied the strength of the response. Thus, temporal as well as spectral parameters were important for the response. When sequences of synthetic sounds mimicking song were effective in evoking an excitatory response, the response was sensitive to the aforementioned manipulations. With these techniques it was possible to elucidate the acoustic parameters required to excite song specific units. All songs of the repertoire eliciting a strong excitatory response contained the appropriate parameters, which were missing from all weakly effective, ineffective, or inhibitory songs. These observations suggest that the ontogenetic modification of integrative neural mechanisms underlying song learning or song crystalization is reflected at the level of single neurons.

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