Eunyoung Yi, Ph.D.
The Research
Johns Hopkins University School of Medicine
Dopaminergic modulation of inner hair cell afferent synaptic transmission
In the inner ear, the inner hair cells convert sound information into electrical signals. Auditory nerve fibers pick up information from the hair cells via the hair cell afferent synapse and transmit the sound signal to the brain. Interesting, auditory nerve fiber activity can be modulated by feedback mechanisms from the brain. Lateral efferent fibers originating in the auditory brainstem innervate auditory nerve fibers at their endings, directly where they contact the inner hair cells. Dopamine is one of the neurotransmitters found in lateral efferent endings and dopamine release is thought to provide a protective role against noise-trauma. However, the cellular mechanisms underlying this process are not well understood. In this project, we will use histological techniques to identify the cellular locations and subtypes of dopamine receptors at the inner hair cell afferent synapse. We will also use electrophysiological techniques to measure electrical impulses in auditory nerve fiber endings at the hair cell afferent synapse in an excised cochlear preparation. We will apply drugs that specifically imitate or inhibit the actions of dopamine, and investigate the mechanisms and intracellular targets by which dopamine receptors modulate the signals at the inner hair cell afferent synapse.