Medicine and Health Sciences Commons^™

Effect Of Epha4 Signaling Mutations On Auditory Function, Michelle R. Gerringer

Dissertations, 2014-2019

Neural pathways underlie the ability of the auditory system to perceive sound. Organization of neural pathways into functional auditory circuitry is accomplished in part by Eph and ephrin signaling proteins. One of these signaling proteins, the EphA4 receptor tyrosine kinase protein, acts as an axon-guidance molecule to aid in target selection and to maintain tonotopicity in the auditory brainstem and midbrain. Genetic mutations of the EphA4 protein have been shown to affect structural auditory development, but there is limited research which shows the functional effects of these mutations. The goal of the present study was to determine the functional effects …

Prepulse Inhibition Of The Acoustic Startle Reflex To Obtain A Psychometric Function In Mice, Robyn Browne

Dissertations, 2014-2019

The acoustic startle reflex (ASR) is an automated motor response to an unexpected and intense auditory stimulus (Ouagazzal, Reiss, & Romand, 2006). When an audible ‘prepulse’ stimulus is presented before the intense, startle-evoking stimulus (SES); the startle reflex response is reduced and this is known as prepulse inhibition (PPI). The degree of ASR inhibition serves as a measure of the behavioral salience of the prepulse (Carlson & Willott, 1996). This study aimed to obtain a psychometric function from the amount of PPI of the ASR that resulted from varying intensity levels of a prepulse stimulus (PPS).

Twelve mice were used …

Release From Masking: Behavioral And Physiological Masking Level Differences, Sarah L. Hodgson

Dissertations, 2014-2019

Binaural hearing offers several advantages over monaural hearing and is believed to be one factor that is involved in the ability to understand speech in background noise. Binaural hearing involves analysis of interaural timing and intensity differences in signals arriving at the two ears which provides listeners with sound localization cues as well as signal in noise detection. When sounds arrive at each ear at slightly different times, there may be a release from the effects of background noise, allowing listeners to detect softer sounds in noise. Masking Level Differences (MLDs) have been widely used to evaluate behavioral binaural processing. …

Variability In Clinically Measured Wideband Acoustic Immittance Over Time In Young And Old Adults, Allison G. Mcgrath

Dissertations, 2014-2019

Wideband acoustic immittance (WAI) measures of the middle ear have the potential to increase our ability to detect changes in the middle ear transfer function not seen using traditional tympanometry. In order to use this new tool diagnostically we must first understand its normal clinical variability. The present study aimed to investigate the variability that occurs when wideband acoustic immittance (WAI) is measured clinically within subjects as a function of subject age, as a function of time, and as a function of pressure. A total of thirty-six ears from eighteen subjects were studied (n=18 young adults ears, n=18 older adult …