11/19/2025
By Lara Thompson

The Francis College of Engineering, Department of Biomedical Engineering, invites you to attend a doctoral dissertation proposal defense by Roni Romero Melendez on: "Exploring the Effects of Virtual Reality (VR)-Based Visual Perturbations on Postural Control and Multisensory Reweighting in Older Adults."

Date: Friday, December 5, 2025
Time: Noon – 1 p.m.
Location: Falmouth 302 Conference Room and via Teams.

Committee:

  • Lara Thompson, Professor of Biomedical Engineering, UMass Lowell (Advisor and Chair)
  • Walfre Franco, Associate Professor and Chair of Biomedical Engineering, UMass Lowell
  • Lynne Gauthier, Associate Professor of Physical Therapy and Kinesiology, UMass Lowell

Abstract
Although there is potential and promise, there have been relatively limited studies utilizing immersive virtual reality (VR) toward the investigation of understanding and improving postural control and balance in older adults, a high fall-risk population. This proposed thesis research examines the effects of virtual reality (VR)-based training and assessment on balance and multisensory reweighting (MSR) in aging individuals. Here, we strive to obtain new knowledge on the effects of VR-based training on standing balance (Aim 1) and walking/gait (Aim 2) during multiple weeks of repetitive training, as well as by investigating older adults’ MSR via a distinctive VR-based visual perturbation stimulus (Aim 3). We hypothesize that, after several weeks of training, standing balance and gait parameters will indicate increased stability, and that a distinctive VR-based visual perturbation stimulus will provide a venue to quantify MSR in older adults.

Aims 1 and 2, involved a 6-week VR-based balance training exercise, twice per week for 10 older adults (76.7±5.85 years old) and 7 younger adults (25.28 ± 3.09 years old). Pre- and post-training assessments included: Aim 1) balance error scoring system (BESS) for which deviations for upright were recorded for regular, tandem (heel-to-toe), and single-leg foot placements on hard surface or foam with eyes closed, activities specific balance confidence (ABC) in which we examined balance confidence for various daily-living scenarios, center of pressure (COP) measured by the forceplate, from which the COP root-mean square and peak-to-peak displacement were extracted, Aim 2) timed up and go (TUG) for which the participants walked 3m (6m round-trip) and we timed the duration, gait parameters (e.g., number of steps, cadence, gait velocity, gait distance) derived from the forceplate, and motion capture (toward examining the anchoring index and absolute angle with standard deviation), and Aim 3) modified sensory organization testing (SOT) using a VR headset and with either firm or foam support surface while the participant stood in six conditions (eyes closed firm surface, eyes closed foam surface, eyes opened firm surface, eyes opened foam surface, VR firm surface, VR foam surface). Aim 3 involving MSR will also involve examining the effects of immersive VR-based visual cues (perturbations) on older adults’ postural control. Previously researched stimuli involved physical perturbations (e.g., a “push”, roll-tilts or translations of a platform), or visual perturbations (movement of a non-immersive visual scene), and white-noise approximated inputs to study MSR in the general population. However, here, we propose a distinctive, multidirectional immersive VR stimulus to study MSR in older adults.

The overall outcome of this research will be a new understanding tied to VR’s effects on motor control and sensorimotor integration in the aging population. Further, this research can also potentially lead to clinical rehabilitation impacts for other balance deficient groups.