Date of Award

Spring 2013

Document Type

Dissertation

Degree Name

Doctor of Audiology (AuD)

Department

Department of Communication Sciences and Disorders

Advisor(s)

Lincoln C. Gray

Mark Gabriele

Brenda M. Ryals

Abstract

Purpose: Murine mammals, more commonly known as mice, emit ultrasonic vocalizations or “yelps” to communicate. It has been found that adult mice use these vocalizations to communicate with each other, and infant mice utilize ultrasonic vocalizations to communicate with their mother. It is known that a relationship exists between hearing ability and vocalization (Bass-Ringdahl, 2010). This study aims to record yelps/ vocalizations of four strains of mouse pups to determine how the development of hearing relates to the vocalizations that are emitted. It is thought that mice with compromised genes that encode for signaling proteins that are essential to the development of auditory connections may emit abnormal vocalizations. Thus, it is possible that the earliest relevant behavior that predicts normal auditory development in mice is the emission of vocalizations of mouse pups. Method: A total of one hundred fifty seven tests of pups between 7 and 26 days age were tested alone in a dark, sound-attenuating booth. The duration of the test time depended on the age of the pup. A B&K model 4939 ¼-inch microphone connected to an Agilent 35670 Spectrum Analyzer recorded all sounds between 10 and 100 kHz above a threshold (40 dB SPL – slightly above background). The yelps emitted were organized into four experimental groups, wild-type (WT), ephrin-B3null, ephrin-B3lacZ, and ephrin-B2lacZ, based on the subject’s genetic strain. A statistical analysis was performed to determine the yelp rate and pitch range of each group of mice. Results: This study found that ephrin-B3null (a traditional knockout) emit significantly more vocalizations than other groups. The ephrin-B3lacZ group that still expresses the protein but has compromised signaling had the fewest total vocalizations, but also the highest percentage of overall sounds in the range of the ultrasonic vocalizations. Conclusions: The Eph/ephrin genotype, known to affect hearing, also affects neonatal vocalizations.

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