Master's Theses

Date of Award

2017

Document Type

Thesis

Department

Biology

First Advisor

Adrián Rodríguez-Contreras

Keywords

Auditory brainstem response; Auditory development; Hearing onset; Maternal care

Abstract

Previous studies in rodents have demonstrated the profound effects that variations in maternal care play during the postnatal development of the brain. However, much less is known about how maternal care affects hearing development. Recently, manipulations of maternal care have been investigated to accelerate hearing onset. We hypothesized that accelerated hearing development results from changes in maternal care behavior. To test this hypothesis, we used a selection model in which natural variations in maternal care were identified in a large cohort of dams by measuring the frequency of different behaviors including LG followed by selection of dams with LG scores higher or lower than one standard deviation from the mean. To measure changes in the development of the auditory system, we assessed startle response and ABR in high-LG offspring and low-LG offspring obtained from selection experiments. We found evidence of differences in hearing development in low-LG offspring compared with high-LG offspring, including early startle responses, statistically significant lower ABR thresholds on P14. Statistical analysis on the latencies and amplitudes of ABR waves (waves I-IV) evoked in peripheral and central auditory system showed statistically significant shorter wave I and wave IV latencies in low-LG offspring compared to high-LG offspring. These results provide evidence that pups reared by high-LG dams have a delayed hearing development compared to pups reared by low-LG dams. A deeper understanding of the mechanisms by which maternal care behavior influences hearing development can provide new insight into the experience-dependent development of hearing in health and disease.

Available for download on Saturday, January 01, 2022

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