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theses

Animals invest heavily in pair bonds and offspring, and benefit if they are able to recognize their family when they are separated. This study investigates how experience modulates the neural memory for auditory signals that can be used in individual recognition, with a focus on parent-offspring interactions in the zebra finch (ZF), a socially-monogamous species with bi-parental care. Bi-parental care, which is rare in mammals, makes this a powerful system in which to study sex differences in neural processing and behavior. Furthermore, auditory brain regions have been identified that respond preferentially to conspecific vocal signals, including songs and various communication calls. This study will focus on the fledgling call (FC), a short, high-frequency call produced in juveniles. FCs signal to parents that offspring need to be fed, and elicit a direct behavioral response. Thus, FCs are a behaviorally-relevant category of vocalization for ZF parents of both sexes, but may be meaningless to adult ZFs that have not yet mated and produced offspring (virgins). Although adult ZFs show behavioral and neuronal memories for the songs and calls of familiar individuals, the neural processing of and behavioral responses to FCs have not been thoroughly examined. Neural processing of these socially-relevant stimuli was assessed in the avian auditory forebrain, in parents and virgin subjects. In addition, parental behaviors elicited by FCs were tested in a novel nest-entry paradigm. Finally, the behavioral and neural data collected from parents were used to determine whether ZF parents can discriminate between the FCs of their own vs. unfamiliar fledglings. Results show that neural responses to FCs are stronger in parents of both sexes than in virgins and that this effect is lateralized. Enhancement of FC responses may be due to differences in multi-unit and single-unit tuning properties that include higher best frequencies in parents, perhaps reflecting a shift toward the high frequencies of FCs. Parents also showed neuronal and behavioral recognition of the calls of their own fledglings, although there were some sex differences. In a nest-entry behavioral paradigm that assesses components of parental feeding responses, FC playback also elicited parental behaviors more frequently in parents than in virgins. However, results showed unexpected sex differences in the frequency of parental behaviors (nest-box entries, food-collected, etc) which support the possibility that male and female parents distribute parental duties in bi-parental species. To further investigate the various sex differences observed and potential neural mechanisms, neural and behavioral responses to FCs were assessed in virgin ZFs that had been treated with the avian analogs of the parental care mediating hormones, vasopressin and oxytocin. Results provide evidence for sex-specific functions of these hormones and establish the ZF as a valuable model for investigating how parental experience affects neural and behavioral processing, in both female and male parents.

ETD_7997

Ph.D.

Includes bibliographical references

by Brittany Alicia Bell

doi:10.7282/T3SQ936T

ETD doctoral

The author owns the copyright to this work.