Maintaining balance requires a complex interplay between sensory and motor processes, and this ability deteriorates with age, impairing daily life activities and contributes to increased fall risks. Importantly, while cognitive-motor interference paradigms suggest an aging-related increase in the cortical involvement in balance regulation, direct evidence remains lacking. To clarify this issue, we assessed the effect of aging on sway-based corticokinematic coherence (CKC), which is a measure of the coupling between cortical electrophysiological signals and postural sway. To that end, we recorded the center-of-pressure fluctuations and electroencephalographic cortical activity of 64 young and 67 older healthy participants performing balance tasks during which sensory information was either removed or altered. We found that older adults showed increased cortical activity that appears to relate to different aspects of closed loop postural control during challenging balance conditions, and correlates with upright stance stability. They also showed increased delays between cortical activity and postural sway, indicative of slower central processing speed. Finally, despite the older cohort displaying significantly altered vestibulo-ocular reflexes, no relationship was found with CKC strength. Overall, our results provide direct evidence that cortical involvement in balance regulation increases with aging. They suggest the feasibility of assessing afferent and efferent processing during balance maintenance, paving the way for studies identifying neurophysiological determinants of fall risks.
Keywords: aging; electroencephalography; postural control; proprioception; vestibular system.