The function and plasticity of lateral olivocochlear efferent feedback to the cochlea throughout life and hearing dysfunction

The type I spiral ganglion neurons (SGNs) of the cochlea are responsible for the transmission of all perceivable sound information to the central nervous system. At rest and during sound stimulation, SGN output is influenced by the efferent feedback from the lateral olivocochlear (LOC) neurons of the brainstem with excitatory and inhibitory input. Recent work has revealed that this input is highly plastic, able to regulate neurotransmitter expression based on noise exposure and switch between two distinct biophysical states during cochlea maturation. Classical lesion studies have revealed that this highly plastic LOC system is important for sound localisation, hearing in noise and selective attention, but our understanding as to how it actually functions in normal hearing and during hearing dysfunction is still very limited. I aim to utilise brain slice electrophysiology alongside imaging based morphological analysis to understand the nature, plasticity, and wiring of the inhibitory and excitatory LOC neurons of the LSO throughout maturation and ageing. I will also use transgenic mice to manipulate hair cell output to understand how feedback from the brainstem adapts to activity of the SGNs.