Growing up singing: Behavioral and physiological perspectives on song acquisition.

Growing up singing: Behavioral and physiological perspectives on song acquisition.

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Bibliographic Details
Author / Creator:	Lusignan, Michael Edward.
Imprint:	2012.
Description:	151 p.
Language:	English
Format:	E-Resource Dissertations
Local Note:	School code: 0330.
URL for this record:	http://pi.lib.uchicago.edu/1001/cat/bib/9370223

Hidden Bibliographic Details
Other authors / contributors:	University of Chicago.
ISBN:	9781267602015
Notes:	Advisor: Daniel Margoliash. Thesis (Ph.D.)--The University of Chicago, Division of the Biological Sciences, and The Pritzker School of Medicine, Committee on Computational Neuroscience, 2012. Dissertation Abstracts International, Volume: 74-01(E), Section: B.
Summary:	Birdsong is one of the most complete models of vocal learning, the capacity for integration of auditory experience into vocal output. A similar capacity for vocal learning is fundamental for human speech development, and many parallels between human language and bird song have been elucidated (Doupe and Kuhl, 1999), despite substantial differences in anatomy and evolutionary distance. In this work, we explore behavioral and physiological changes across song development in order to place these changes in a developmental context. In particular, we have focused on three studies surrounding the transition from subsong, a period of vocal motor behavior similar to babbling in human language development, and plastic song, the first stage in which learned vocalizations are produced. We report here a procedure for quantifying the final transition to plastic song through behavioral measures. The vocalizations of zebra finches ( Taeniopygia guttata) learning either from live tutors or through operant conditioning and automated playback were captured. Vocalizations were segmented, and daily distributions of vocal segments in multidimensional spectral feature space were estimated. From this multimodal distribution, an entropy characterizing the vocal state for each day was calculated. Among live tutored birds (n=9) and operant tutored birds (n=5), the trajectory of this entropy degraded after first exposure to a tutor song, indicating a reduction in the covariances of the individual distributions of vocal segments. This trajectory approached an asymptotic low, implying a period of low vocal change. The timing of entry into this period of low vocal change varies by training paradigm, with birds learning through live tutoring reaching asymptotic performance at a mean of 15.7 ± 2.7 days (s.e.m.) and birds learning through operant conditioning reaching asymptotic levels of performance at a mean of 19.6 ± 2.8 days (s.e.m.). Analyses of song structure through HMM training was used to demonstrate the stability of the song after reaching asymptotic vocal performance. The neural response in the robust nucleus of the arcopallium, a motor output in the bird song system specialized for vocal motor behavior was repeated evaluated across song development in a subset of the juvenile zebra finches examined behaviorally. Activity was collected through single electrode electrophysiology at various points during song development for birds learning from a live tutor (n=6) or through operant conditioning (n=2). At each neural site, a set of auditory stimuli were presented, including the three adult songs used in operant tutoring, two juvenile songs, and two exemplars from the juvenile's own vocal output of the previous day. For birds tutored through a live tutoring paradigm, this stimulus set also included an exemplar of the bird's tutor after initial tutor exposure. Auditory response was assessed through a modified d′ measure. Strong auditory response was primarily limited to exemplars of the bird's own song. The timing of strong auditory response emerged with substantial variability all eight birds relative to the initial exposure of the tutor song. Relative to timing of the individual's attainment of asymptotic vocal behavior, however, the timing of the emergence of auditory response was tightly correlated. We propose that the strong correlation and linear relationship between the emergence of auditory response and attainment of asymptotic vocal behavior indicates a common underlying process for both phenomena, the transition to plastic song. We examined nightly changed in spectral features, a phenomenon with a demonstrated link to song learning efficacy, by administering bilateral electrolytic lesions to nucleus HVC. HVC is a sensorimotor nucleus in the avian song system and implicated both in the control of song behavior in adults and in the drive of neural activity in nucleus RA. Lesions were administered either before or following the introduction of a tutor song. A subset of birds received lesions after initial tutor exposure (n=4), and, in three of the birds, nightly spectral feature degradation dropped near zero following the lesion. Among the bird lesioned prior to initial tutor exposure (n=2), neither manifested a nightly deterioration in spectral features. In those birds lesioned after tutoring, vocalizations deteriorated to a subsong like state, as described in cite Aronov (2008). While the sample size is relatively small, these results imply that the nightly degradation of spectral features across sleep requires an functioning HVC.