Biology subjects

DiBianca, S. J.

Publications and source records attributed to DiBianca, S. J..

3 recordsLinked to original sources

bioRxiv2025

The Relationship Between Visual Motion Detection Thresholds and Visual Sensitivity to Medial/Lateral Balance Control

The ability to differentiate between self-motion and motion in the environment is an important factor for maintaining upright balance control. Visual motion can elicit the sensation of a fall by cueing a false position sense. While there is evidence supporting the role of central vision and fall risk, including measures of contrast sensitivity, depth perception, and size of the visual field, the relationship between motion detection thresholds and balance control remains unknown. The aim of this study is to explore the relationship between thresholds for visual motion detection (VMDTs) of the environment and measures of visual sensitivity to balance disturbances in the environment while walking. Thirty young adults (18-35 years) and thirty older adults (55-79 years) participated in a counter-balanced study where they 1) walked on a self-paced treadmill within a virtual environment that delivered frontal plane multi-sine visual disturbances at three amplitudes (6{degrees}, 10{degrees}, and 15{degrees}), and 2) performed 100 trials of a two-alternative forced choice (2AFC) task in which they discriminated between a counterclockwise ("left") and clockwise ("right") rotation of a visual scene under three conditions (standing, standing with optic flow, and walking). Visual sensitivity was measured using frequency response functions of the center of mass displacement relative to the screen tilt (cm/deg) while VMDTs were measured by fitting a psychometric curve to the responses of the 2AFC task. We found significant positive correlations between measures of visual sensitivity and VMDTs for 7 out of the 9 conditions in young adults, and nonsignificant positive correlations between the two measures in older adults. VMDTs were overall higher in older adults, although not significantly in the standing condition, indicating more motion in the environment is required for older adults to consciously perceive it. VMDTs also tended to increase from standing, standing with optic flow, and walking, although not significantly between the standing and standing with optic flow conditions for both populations. We interpret the positive correlations between the two measures as an indication that individuals with lower motion detection thresholds can more accurately differentiate between self-motion and motion in the environment, resulting in lower responses from visual disturbances in the environment.

neuroscience↗

bioRxiv2024

SENSITIVITY OF MEDIAL/LATERAL BALANCE CONTROL TO VISUAL DISTURBANCES WHILE WALKING IN YOUNG AND OLDER ADULTS

Humans integrate multiple sources of sensory information to estimate body orientation in space. Balance control experiments while standing provide evidence that the contributions of these sensory channels change under different conditions in a process called sensory reweighting. This study aims to address whether there is evidence for sensory reweighting while walking and explores age-related differences in medial/lateral balance control under visually perturbing walking conditions. Thirty young adults (18-35 years) and thirty older adults (55-79 years) walked on a self-paced treadmill within a virtual environment that delivered frontal plane multi-sine visual disturbances at three amplitudes (6{degrees}, 10{degrees}, and 15{degrees}). Frequency response functions were used to quantify visual sensitivity to balance disturbances, while spatiotemporal gait parameters (e.g., step width, step-width variability) were measured to assess balance control. Visual sensitivity decreased in both populations with increasing stimulus amplitude, analogous to the sensory reweighting hypothesis in balance control while standing. Despite the decrease in visual sensitivity, the compensatory upweighting of other sensory systems was not observed through measurements of remnant sway. Older adults exhibited higher visual sensitivity at all amplitudes compared to young adults, indicating a more sensitive response to visual disturbances to balance control. Both groups showed increases in step width and step width variability with higher visual amplitudes, with older adults demonstrating more pronounced effects. Weak correlations existed between changes in visual sensitivity and changes in step width and step width variability suggesting a limited interaction between sensory reweighting and gait stability.

neuroscience↗

bioRxiv2023

Visual Motion Detection Thresholds Can Be Reliably Measured During Walking and Standing

In upright standing and walking, the motion of the body relative to the environment is estimated from a combination of visual, vestibular and somatosensory cues. Associations between vestibular or somatosensory impairments and balance problems are well established, but less is known about how the ability of the visual system to detect motion affects balance control. Here we asked whether motion detection thresholds can be reliably measured during walking and standing. Typically, motion threshold values have been obtained while sitting, with the head fixated to eliminate self-motion. In this study we 1) tested whether a visual motion detection threshold can be reliably measured during standing and walking in the presence of natural self-motion; and 2) investigated whether visual motion detection thresholds differ during standing and walking. MethodsTwenty-nine subjects stood on and walked along a self-paced, instrumented treadmill inside a virtual environment displayed on a large dome. Participants performed a 2-alternative forced choice experiment in which they discriminated between a counterclockwise ("left") and clockwise ("right") rotation of a visual scene projected on a large dome. A 6-down 1-up adaptive staircase algorithm was implemented to change the amplitude of the rotation. A psychometric fit to the participants binary responses provided an estimate for the detection threshold ResultsWe found strong correlations between the repeated measurements in both the walking (R = 0.84, p < 0.001) and the standing condition (R = 0.73, p < 0.001) as well as good agreement between the repeated measures with Bland-Altman plots. Average thresholds during walking (mean = 1.04 degrees, SD = 0.43 degrees) were significantly higher than during standing (mean = 0.73 degrees, SD = 0.47 degrees). ConclusionVisual motion detection thresholds can be reliably measured during both walking and standing, and thresholds are higher during walking.

neuroscience↗