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Date of Award

Fall 2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Neuroscience

Supervisor

Suzanna Becker

Co-Supervisor

Ian C. Bruce

Language

English

Committee Member

James Reilly

Abstract

Tinnitus is an auditory disorder characterized by the perception of a ringing, hissing or buzzing sound with no external stimulus. Because the most common cause of chronic tinnitus is hearing loss, this neurological disorder is becoming increasingly prevalent in our noise-exposed and ageing society. With no cure and a lack of effective treatments, there is a need for a comprehensive understanding of the neural underpinnings of tinnitus. This dissertation outlines the development and validation of a comprehensive theoretical model of cortical correlates of tinnitus that is used to shed light on the development of tinnitus and to propose improvements to tinnitus treatment strategies.

The first study involved the development of a computational model that predicts how homeostatic plasticity acting in the auditory cortex responds to hearing loss. A subsequent empirical study validated a more biologically plausible version of this computational model. The goal of these studies was to determine whether and how a form of plasticity that maintains balance in neural circuits can lead to aberrant activity in the auditory cortex. The final study extends the validated computational model to develop a comprehensive theoretical framework characterizing the potential role of homeostatic and Hebbian plasticity in the development of most major cortical correlates of tinnitus.

These theoretical and empirical studies provide a novel and complete description of how neural plasticity in adult auditory cortex can respond to hearing loss and result in the development of tinnitus correlates.

McMaster University Library

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