Adaptations of postural sway dynamics and cortical response to unstable stance with stroboscopic vision in older adults

Abstract

Background: Stroboscopic vision (SV), intermittent visual blocking, has recently been incorporated into postural training in rehabilitation. This study investigated interactions of postural fluctuation dynamics and cortical processing for the elderly during stabilometer stance with SV.Methods: Thirty-five healthy elderly maintained an upright stance on a stabilometer. Along with postural fluctuation dynamics, EEG relative power and EEG-EEG connectivity were used to contrast neuromechanical controls of stabilometer stance with SV and full-vision.Results: Compared with the full-vision, SV led to greater postural fluctuations with lower sample entropy and mean frequency (MF). SV also reduced regional power in the mid-frontal theta cluster, which was correlated to SV-dependent changes in the size of postural fluctuations. SV also enhanced the alpha band supra-threshold connectivity in the visual dorsal and frontal–occipital loops of the right hemisphere, and the supra-threshold connectivity from Fp2 positively related to variations in the MF of postural fluctuations.Conclusion: SV adds challenge to postural regulation on the stabilometer, with the increasing regularity of postural movements and fewer corrective attempts to achieve the postural goal. The elderly shift over-reliance on visual inputs for posture control with more non-visual awareness, considering deactivation of the dorsal visual stream and visual error processing.

Beta cortical oscillatory activities and their relationship to postural control in a standing balance demanding test: influence of aging

“…Furthermore, there is strong evidence for the crucial contribution of the cerebral cortex in the control of balance (Jacobs and Horak, 2007;Maki and McIlroy, 2007;Papegaaij et al, 2014). A growing number of studies have demonstrated increasing cortical activities in more challenging balance conditions (Wittenberg et al, 2017;Malcolm et al, 2021;Barollo et al, 2022;Tsai et al, 2022). Specifically, cortical activity and high-order cognitive processes are important when static postural control is challenged by mechanical and sensory perturbations, as the responsive adjustments depend on the integration of reliable sensory feedback and planning and execution of appropriate motor responses (O'Connor and Kuo, 2009;O'Connor et al, 2012;Francis et al, 2015;Franz et al, 2015Franz et al, , 2017Goodworth et al, 2015;Malcolm et al, 2021;Tsai et al, 2022).…”

“…As suggested by current electroencephalography (EEG) studies, multiple brain regions and cortical beta band (13-30 hz) electrical activities are involved in maintaining upright static balance in adults (Ibitoye et al, 2021;Malcolm et al, 2021;Barollo et al, 2022;Tsai et al, 2022). The parietal-occipital region, frontal-central region, and occipital lobe are involved in response to visual challenges while standing (Chang et al, 2016;Malcolm et al, 2021;Tsai et al, 2022). Parietal and central areas beta band power were sensitive to proprioceptive challenges while standing (Tse et al, 2013).…”

“…Recent EEG work (Ibitoye et al, 2021;Malcolm et al, 2021;Tsai et al, 2022) has started to examine age-related changes on the cortical control of upright stance, confirming prior evidence suggesting (Rubega et al, 2021) that the cortical neural activities during the balance task also changes along with aging and are associated with poor postural control and higher fall risk (St George et al, 2021). However, while modifications to stance and visual feedback have been primarily used in studies examining age-related changes, a wider examination of age-related changes due to sensory manipulation and mechanical perturbations could provide valuable information about aging's effect on cortical contributions to balance control in more complex environments, crucial for linking to changes in fall risk.…”