Title: Exploring the effects of aging on vestibular perception of rotation during standing.
Supervisor: Dr. Mark Carpenter
Committee members: Dr. Romeo Chua, Dr. J. Timothy Inglis
Abstract:
Despite its seemingly effortless execution, standing balance is a complex task that is maintained through sensory inputs from the visual, somatosensory, and vestibular systems. The vestibular system, located in the inner ear, plays an integral role in maintaining standing balance and interpreting our perception of self-motion. Assessments of vestibular perception and functioning often rely on tests involving determining perceptual thresholds of motion (e.g., sinusoidal rotations) or examining vestibular-evoked reflexes (e.g., vestibulo-ocular reflex). While these methods of assessing vestibular functioning have demonstrated reliability in testing thresholds and reflexes at the level of the periphery, they do not assess central vestibular functioning and are often not robust enough to demonstrate how the well-known physiological deterioration of the vestibular system seen in aging is affected. Moreover, these tests are often performed while seated in a chair, and little to no research has assessed vestibular perception of motion while standing, in which we also see deficiencies in the older adult population. Therefore, the purpose of this thesis is to examine the effects of aging on peripheral and central vestibular contributions to vestibular perception of rotation while standing.
Healthy young (18-64 years old) and older (>65 years old) will be recruited to stand on a custom-built rotating platform and will be instructed to track the rotation of the platform using a rotary dial mounted directly in front of them. The platform rotation will consist of four different pseudorandom profiles (0.02-0.11 Hz; ±30°) with a single trial lasting 113 seconds. Participants will perform four consecutive trials with their eyes closed, with each trial consisting of a different platform rotation profile. To assess peripheral vestibular functioning of the semicircular canals, a test of the vestibulo-ocular reflex will be performed using a rotating chair and quantified using electro-oculography. To assess visual-vestibular interaction of the utricle, a subjective visual vertical test will be performed using a rotating bucket and a vertical line aligned with Earth’s vector of gravity. Assessments of balance deficits will be done using a combination of perturbed (i.e., standing on foam) and unperturbed two- and one-legged stance tasks quantified through inertial measurement units placed on the trunk. To assess for test-retest reliability, participants will complete a second block of four pseudorandom rotation trials back on the platform.
The results from this thesis may provide insight into how aging affects vestibular perception of motion and standing balance and can potentially lead to the creation of diagnostic testing methods that can possibly distinguish between central and peripheral vestibular deficits in vestibular patients (e.g., vertigo) and/or older adults.