Research Career Enhancement Award, American Physiological Society
Gordon Res. Conference Young Investigator Award, NASA-NSF
Dale and Rushton Fund Award, Physiological Society
This laboratory's research is focused on hair cells of the vestibular system. The vestibular system of the inner ear senses accelerations of the head and interacts with other systems to produce the sensation of balance. It is estimated that more than one third of adults in the US experience vestibular dysfunction at some time in their life. However the mechanisms underlying normal and abnormal processing of vestibular sensory signals are not well understood. Our research aims to elucidate how signals are processed in the peripheral vestibular system using rodent models.
Mechanoreceptive hair cells in the vestibular periphery convert tiny mechanical displacements of the hair cell bundle into electrical signals which are transmitted by vestibular afferent nerves to the brain. Type I and type II hair cells are found in the vestibular systems of mammals, birds and reptiles. The two hair cell types differ in several respects including their innervation characteristics. Whereas bouton afferent nerve terminals make synaptic contact with a small portion of the type II hair cell basolateral membrane, calyx-shaped afferent terminals engulf the basolateral surface of one or more type I hair cells. In order to understand how signals are transformed from a mechanical stimulus at the type I hair cell bundle into electrical activity of calyx afferents we use electrophysiological (patch clamp), molecular and mathematical modeling approaches. We have identified several different types of potassium channels in vestibular cells and are currently assessing their modulation by candidate efferent transmitters and ototoxic drugs. It is hoped that results from these studies will clarify some of the mechanisms underlying vestibular disorders.
Meredith FL, Brown, N, Rennie KJ. Dopaminergic Inhibition of Sodium Currents in Vestibular Calyces. Assoc. Res. Otolaryngol. 45th mid-winter meeting 2022.
Gherke B, Meredith FL, Dondzillo A, Vu T, Rennie KJ. Aging and Dysfunction in the Peripheral Vestibular System. ENDURE, Diversity Poster Session, Society for Neuroscience Meeting, 2022.
Dopaminergic inhibition of Na+ currents in vestibular inner ear afferents Frontiers Neurosci 2021
Meredith F.L., Rennie K. J. Persistent and resurgent Na+ currents in vestibular calyx afferents. J. Neurophysiol. 124: 510-524, 2020.
Meredith FL, Rennie KJ. Regional and Developmental Differences in Na( ) Currents in Vestibular Primary Afferent Neurons. Front Cell Neurosci. 2018;12:423. PubMed PMID: 30487736
Kirk ME, Meredith FL, Benke TA, Rennie KJ. AMPA receptor-mediated rapid EPSCs in vestibular calyx afferents. J Neurophysiol. 2017 Jun 1;117(6):2312-2323. PubMed PMID: 28298303