Minimally invasive electrophysiological measurement of cochlear function.

The inner ear or cochlea converts sound vibrations into electrical signals. There are two fundamental components to this conversion. The cochlea filters the sound, so that cells arranged along the length of the cochlea respond to different sound frequencies: this leads to frequency selectivity of these cells. Secondly, the oscillatory or vibration character of sounds is preserved in the electrical signals: this is called phase-locking. Frequency selectivity is fundamental to hearing and is degraded in inner ear diseases. Phase-locking is essential for the localization of sounds in space. However, the exact limits of these two processes are not known in humans: this lack of fundamental knowledge hampers remediation of deafness, e.g. by cochlear implants. In this project we aim at a characterization of these two processes by means of minimally invasive electrical measurements in the middle ear. We will develop stimuli and analysis to record mass electrical potentials of the inner ear and auditory nerve of experimental animals, and to relate these potentials to the underlying generators at the single neuron level. As a further test we will examine the effects of efferent activation on frequency tuning and phase-locking, so as to assess the influence of the central nervous system on peripheral cochlear processing. The knowledge and expertise acquired will allow us to evaluate strategies to record and interpret these potentials from normal hearing volunteers or neurosurgical patients in future projects.

Keywords:sound, hearing, neuroscience, brain, frequency

Disciplines:Neurosciences, Biological and physiological psychology, Cognitive science and intelligent systems, Developmental psychology and ageing