EVALUATING THE NEUROANATOMY AND PHYSIOLOGY OF THE DORSAL COCHLEAR NUCLEUS DURING SENSORINEURAL HEARING LOSS

Helen Keller famously stated that “deafness separates people from people”, a strong underscore to the importance of hearing. Unfortunately, approximately 20% of the world’s population suffer from hearing loss, with 5% of those affected having a more severe form. Sensorineural hearing loss (SNHL) is the most common form of hearing impairment, characterized by pathology of the cochlea, auditory nerve, and central nervous system. The two major types of SNHL are age-related hearing loss (affecting nearly half of those aged > 75 years in the United States) and noise-induced hearing loss (affecting around 400 million people globally). Both of these types of SNHL not only affect the peripheral auditory system but also affect central auditory brain structures, like the cochlear nucleus (the first brain structure to receive and process auditory information from the cochlea). Understanding how these two types of SNHL affect the morphology and physiology of neurons within the cochlear nucleus (specifically the dorsal cochlear nucleus) aids in our understanding of how the auditory system is altered and overcompensates (central gain) for the loss of auditory input. Through this body of work, I illustrate how key neuronal cell types in the dorsal cochlear nucleus alter their structure and function in response to age and loud noise exposure. My findings are expected to add nuance to the story of central gain, detailing how gradual (age-related) and acute (noise-induced) hearing loss affect key auditory neuronal function. These findings have the potential to help facilitate discovery of novel cochlear and brainstem implant approaches.