Developing models of inner ear disorders to form better therapeutic approaches in humans

The inner ear is comprised of two bony labyrinths that contain the vestibular and cochlear membranes.  Along these membranes are specialized cells known as hair cells.  A delicate pressure system of these fluid filled labyrinths allows the propagation of sound wave energy and gravitational plane to transform information about the auditory environment in relation to head position in space into neural signals that travel along the vestibulocochlear nerve to the brainstem nuclei.  Damage to any part of these delicate system can lead to hearing loss and vestibular dysfunction that is devastating to human quality of life.  These projects will create animal models of the prominent inner ear disorders in order to better evaluate and develop treatments that improve quality of life or eradicate symptoms all together.  

A model of 3rd Window Syndrome

In humans, a natural or injury induced dehiscence (hole) in the bones of the vestibular or cochlear labyrinth can induce a disorder known as 3rd Window Syndrome.  Typically sound enters the auditory system first by being transduced through the oval window (OW) via the middle ear bones (ossicles).  The energy wave propagates through the liquid filled labyrinth over where it activates the hair cells prior to exiting through the round window (RW).  A "3rd Window" leads to diminished or inappropriate signals being conducted down the vestibulocochlear nerves to the brain.  This can induce pseudo-conductive hearing loss, vertigo, and even cognitive dysfunction.  This project will establish an animal model of 3rd window syndrome with which to explore the central plasticity that leads to these cognitive impairments and hopefully to develop better or novel treatments for the long term symptoms associated with this inner ear disorder.  

Developing treatments and preventative measures for Noise Exposure Induced Hearing Loss (NIHL)

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Noise exposure is the leading cause of hearing loss in healthy adults.  Aside from noisy work environments (e.g., construction) and military deployment, humans are increasingly exposing themselves to damaging levels of sound via headphones and other entertainment (e.g., concerts). In the coming decades earlier and more profound onsets of hearing loss will be present world wide.  Our basic understanding of how noise leads to inner ear hair cell/nerve damage has lead to the initial progress in treating and preventing NIHL. Currently there is not an effective treatment, and prevention typically requires bulky/expensive equipment. This project will use an animal model of permanent and transient noise induced hearing loss to explore preventative and treatment "gene therapy" approaches.  Not only will we investigate the effects of  noise-induced sensorineuronal hearing loss, but we will also begin to advance our understanding of "hidden" hearing loss through collaborations with Dr Antje Ihlefeld's research group.  Finally, we will look at the relationship between the onset of peripheral hearing loss and its correlations with the onset of cognitive impairments in aging individuals. This line of research will investigate the central maladaptive plasticity associated with the onset of peripheral noise induced hearing loss.