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Kristen Dissertation

Early auditory experience shapes auditory fMRI and ERP responses in the adult zebra finch

  Early auditory experience shapes auditory fMRI and ERP responses in the adult zebra finch




by: Kristen K. Maul

 

 Speech-Language-Hearing Sciences  

for the degree of Doctor of Philosophy, The City University of New York. 2009

Advisors: Dr. Ofer Tchernichovski & Dr. Lucas C. Parra

 

Abstract

            Both humans and songbirds acquire their species and culture specific vocalizations during early life by imitating adult individuals. In addition to changes in vocal production, auditory responses become selective to the species-specific or cultural vocalizations. What sort of auditory, vocal and social experiences are required to shape those responses? The ability to control the sensory environment of the songbird during vocal development can increase understanding of the role of environment in human language development, providing that sensory changes can be compared across species. Consequently this dissertation focused on developing functional Magnetic Resonance Imaging (fMRI) as well as Event Related Potentials (ERPs) methods that can be used to test how early auditory experience shapes responses in the auditory forebrain of the songbird.  For both fMRI and ERP custom-made hardware and software were created for scanning, recording and analyzing responses to songs and calls. Combining fMRI with ERPs permitted examination of the structure of auditory responses in both brain-space and in time. Converging evidence from both methods showed that adult male birds kept in isolation over the sensitive period for song learning showed no consistency in auditory responses to conspecific songs, calls, and syllables. Thirty seconds of song playback each day over development was sufficient to shape stimulus-specific responses. Strikingly, adult females kept in isolation over development showed responses similar to those of males that were exposed to songs. Our findings suggest that early auditory experience with songs may be required to tune perception towards conspecific songs in males, but not in females. Suggesting that early auditory experience with songs may be required to tune perception towards conspecific songs in males, but not in females.  Overall, Evoked Potentials and fMRI in the zebra finch are sensitive to acoustic differences in stimuli and these methods could be useful tools to study metrics of song, and song syllable and perhaps perception. Using fMRI and ERP in zebra finches should permit repeated measurements in the same subject over development, and may promote cross-species comparison between songbirds and humans.

 


 

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