Systematic assessment of the cortical oscillatory dynamics of postural control across a visual availability gradient: A pilot study

Maintaining upright stance requires the continuous integration of visual, vestibular, and somatosensory signals. When one sensory channel is compromised, the nervous system is forced to adopt compensatory strategies to offset the loss of sensory information. Despite growing interest in the neural underpinnings of postural regulation, the relationship between cortical oscillatory dynamics and balance performance across different sensory conditions remains largely unexplored. Alpha band activity, particularly individual alpha peak frequency (iAPF), has been associated with individual differences in sensorimotor processing and perceptual timing [1], yet its link to postural sway under varying visual inputs has not been systematically investigated. Research Question Do iAPF variations relate to changes in postural sway across graded visual manipulation? Methods Seven healthy adults stood on a posturographic platform wearing a 64-electrodes EEG cap and an XR headset. EEG and postural signals were recorded synchronously via LabStreamingLayer. Three visual states were tested: Eyes Open (EO), Eyes Closed (EC) and Eyes Blurred (EB), obtained using an opaque nylon filter. Postural sway was quantified by the ellipse area of the centre of pressure (COP). EEG signals were preprocessed through re-referencing, band-pass filtering, and AMICA-based artefact removal. iAPF was computed as the peak of the power spectral density within the alpha band (7–13 Hz) [2]. A linear mixed-effects model with permutation tests estimated state-specific iAPF regression slopes (βiAPF) [2]. Results A significant iAPF × visual state interaction was found on COP area (F = 21.67, pperm < 0.05 – nperm = 1000). Visual state-specific slopes revealed a positive effect of iAPF under EB (βiAPF = 18.14, 95% CI [3.88 32.39]) and EC (βiAPF = 19.71, 95% CI [-7.41 46.82]), and a negative effect under EO (βiAPF = −16.03, 95% CI [−46.27 14.22]), indicating that visual availability may modulate the relationship between iAPF and postural sway. Discussion These preliminary findings suggest that under degraded visual input, higher iAPF is associated with greater sway area, possibly reflecting less efficient exploitation of the remaining sensory information, while under full visual availability this relationship seems to reverse, promoting a more refined visual feedback integration. This is consistent with the role of alpha oscillations in sensory gating [3], suggesting iAPF may index visual cortical allocation during stance. An element of novelty introduced here is the systematic manipulation of visual availability across a controlled visual gradient, which enabled a methodical assessment of how visual information may modulate cortical involvement in balance regulation. Future work will replicate these findings in a larger cohort and extend the analysis to other sensory perturbation (e.g. proprioceptive), applying spectral and connectivity techniques to better characterise the cortical signatures of postural control.