Response properties of the inferior colliculus following unilateral noise induced hearing loss : the effects of cholinergic enhancement and auditory training

Abstract

Tinnitus is a common and potentially debilitating condition that is often associated with hearing loss. Noise induced hearing loss is a frequently utilised animal model, in studies investigating the underlying mechanisms of tinnitus. In the central auditory system, the inferior colliculus (IC) is an obligatory nucleus for the ascending processing of auditory signals. It has been comprehensively investigated in animal models of unilateral noise induced hearing loss (UNIHL). Previous studies have mostly investigated the dominant, contralateral pathway with little attention being paid to the ipsilateral path. In normal hearing animals, contralaterally driven IC neurons are primarily excitatory while ipsilaterally driven IC neurons are primarily inhibitory. However, there are also ipsilaterally driven IC neurons that are excitatory. Literature that have investigated the response properties of these neurons, and their consequential response properties within an animal model of UNHIL is very limited. The first study presented in this thesis investigated the consequences of UNIHL of both dominant contralaterally excitatory and non-dominant ipsilaterally excitatory neurons of the IC. The findings in this thesis may have implications for the development of therapies for tinnitus. By using a human equivalent dose of an approved drug, paired with a well-known neuro-rehabilitation intervention, together these interventions can significantly affect the consequential response properties of IC neurons that are observed following acoustic trauma. In a condition where currently there are no reliable cures, further development of these findings may provide insights that could lead to the generation of novel therapeutic approaches.

Date of Award	2020
Original language	English