Slowed sensory reweighting and postural illusions in older adults: the moving platform illusion

Abstract

We investigated whether postural aftereffects witnessed during transitions from a moving to a stable support are accompanied by a delayed perception of platform stabilization in older adults, in two experiments. In experiment 1, postural sway and muscle cocontraction were assessed in 11 healthy young, 11 healthy older, and 11 fall-prone older adults during blindfolded stance on a fixed platform, followed by a sway-referenced platform and then by a fixed platform again. The sway-referenced platform was more compliant for young adults, to induce similar levels of postural sway in both age groups. Participants were asked to press a button whenever they perceived that the platform had stopped moving. Both older groups showed significantly larger and longer postural sway aftereffects during platform stabilization compared with young adults, which were pronounced in fall-prone older adults. In both older groups elevated muscle cocontraction aftereffect was also witnessed. Importantly, these aftereffects were accompanied by an illusory perception of prolonged platform movement. After this, experiment 2 examined whether this illusory perception was a robust age effect or an experimental confound due to greater surface compliance in young adults, which could create a larger perceptual discrepancy between moving and stable conditions. Despite exposure to the same surface compliance levels during sway-reference, the perceptual illusion was maintained in experiment 2 in a new group of 14 healthy older adults compared with 11 young adults. In both studies, older adults took five times longer than young adults to perceive platform stabilization. This supports that sensory reweighting is inefficient in older adults. NEW & NOTEWORTHY This is the first paper to show that postural sway aftereffects witnessed in older adults after platform stabilization may be due to a perceptual illusion of platform movement. Surprisingly, in both experiments presented it took older adults five times longer than young adults to perceive platform stabilization. This supports a hypothesis of less efficient sensory reintegration in this age group, which may delay the formation of an accurate postural percept.

Sensory integration research: priority scientific directions based on the analysis of Web of Science Core Collection resources

“…The design of the study [38] involved assessing postural balance while standing blindfolded on a fixed platform, then on a fixed platform, and then again on a fixed platform. The sway-oriented platform was more malleable for young adults and elicited similar levels of sway in both age groups.…”

Induced effects of electrical muscle stimulation and visual stimulation on visual sensory reweighting dynamics during standing on a balance board

“…Numerous studies have demonstrated that the change in sensory weights, known as sensory reweighting dynamics, will differ depending on the nature of the subjects. Even if subjects are categorized within the same group (e.g., healthy, elderly, or stroke patients), the reweighting dynamics within each group may differ considerably [7][8][9][10]. Therefore, it is important to consider approaches to improve postural stability according to the individual characteristics in the reweighting dynamics.…”

Dissociating proprioceptive deficits in Autism Spectrum Disorders: Intact acuity but impaired sensory integration in postural control

“…Proprioceptive integration was assessed using postural adaptation to an inaccurate proprioceptive environment, tested in three phases: baseline, adaptation and reintegration (Craig & Doumas, 2019; Doumas & Krampe, 2010). In this task, participants stand on a fixed surface with eyes closed, i.e.…”