Age-related and cell-type-specific changes in auditory cortical processing

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Ageing is unavoidable. Of age-related changes in our body, age-related hearing loss (ARHL) is a serious issue for us. ARHL is one of the top three most common chronic health conditions affecting individuals aged 65 years and older in the US. In the UK nearly 6.4 million elderly people suffer from some form of hearing loss. It is predicted that this number will increase further. Indeed the World Health Organisation predicts that by 2030 adult onset hearing loss will be in the top ten disease burdens in the UK, above diabetes. Although ARHL per se won't kill us, its impact is huge: ARHL significantly decreases the one's ability to communicate with others, resulting in a significant impact on daily life. Another change in hearing with age is the slowness of auditory processing. Again this age-related slowness in auditory processing leads difficulty in daily communication. One way to address these societal issues is a better understanding of the ageing auditory system.In this proposal we will investigate how ageing affects auditory information processing in the auditory brain, particularly the auditory cortex, which is essential for speech comprehension in humans. In the auditory cortex there are lots of types of neurons, but we know little about how such diverse neurons communicate with each other and how neuronal communications are changed with age. In this proposal we will particularly focus on one of two major neuron groups, called inhibitory neurons because we know that inhibitory circuits are affected by ageing in other auditory brain areas, but we know little about inhibitory circuits in the ageing auditory cortex.We will test the hypothesis that auditory processing in the auditory cortex is changed with age depending on cell-types.To this end, we will combine advanced technologies in animal models. One technology is called massively parallel neural recording technique, which allows us to readout activity from a hundred of neurons simultaneously. Another technology is called optogenetics, which allows us to control neuronal activity with light in a cell-type-specific manner. We are specifically aiming to achieve two goals in this proposal: firstly we will characterise how ageing affects information processing in inhibitory neurons of the auditory cortex.Secondly by activating inhibitory neurons with light we will assess how ageing can change abilities of inhibitory neurons in the auditory cortex.Our study will provide further insights into the mechanisms of age-related changes in auditory processing and the development of novel intervention strategies for the ageing auditory system.