a) Background and need for the research.
Age-related hearing loss (ARHL), also known as presbycusis, is the most common health condition in the elderly. It is a progressive disorder leading to a decreased ability to understand speech, especially in a noisy environment. ARHL is also associated with social isolation, depression, and an increased risk for neurodegenerative diseases such as dementia. Approximately half of adults in their 70’s exhibit ARHL that is severe enough to affect communication. It is expected that approximately 14.5 million people in the UK will be affected by hearing loss by 2030, with ARHL as the single biggest cause of it. The large impact of ARHL on human health is mainly due to the increased lifespan of humans, and to the fact that our ears cannot cope with the harmful conditions present in modern society.Currently, we know very little about why we progressively lose the sense of hearing with age, making it impossible to develop effective treatments to either prevent, slowdown or even reverse ARHL.
b) The main aims.
One of the main features of the aging auditory system is the change in the number of connections between the sensory cells, which are responsible for converting sound into electrical impulses, and the nerve fibres that allow these cells to send or receive information to/from the brain. In particular, recent finding shows that the neural connections descending from the brain change the sensory cell they connect to in aged mice. Therefore, the project aims to understand whether this ‘re-wiring’ exists in ARHL mouse models and if so, to determine the time course of these changes and whether they are protective against, or exacerbating, ARHL.
c) An outline of the research method.
During the PhD the student will measure the function of sensory cells in the auditory organ using a technique called electrophysiology. Electrophysiology allows us to measure the tiny electrical currents produced by sensory cells as they convert sound into an electrical signal that can be understood by the brain. The student will also use techniques to measure the hearing ability of mice, similar to those used when diagnosing hearing loss in people. The student will aslo determine whether molecules crucial for normal hearing function are still present in the aged cochlea; this will be achieved using a technique called immunostaining.
d) How people with hearing loss will benefit from the research.
Currently, there is an urgent need for therapies to slow down or even reverse the progressive nature of ARHL. Recent developments in gene replacement technologies in mice have highlighted potentially promising therapeutic treatments. However, these types of approaches will rely on having an understanding of the genes and molecules responsible for ARHL. This project will identify some of the crucial mechanisms leading to ARHL, which will lead to the identification of targetable genes allowing the development of diagnostic and therapeutic interventions in humans.
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