Age related alteration in EEG evoked responses to balance perturbations on an inclined surface

Falls in older adults are often worsened by environmental challenges, such as sloped terrain, which increase the demands on the control of upright stability. Studying cortical activities evoked by perturbations under such conditions can help elucidate the neural mechanisms underlying postural control. This study investigated age-related differences in cortical responses to slope-induced forward perturbations and whether these responses primarily reflect reactive motor control to regain balance. Ten older and ten young adults underwent lean-and-release perturbations on a slope while electroencephalography (EEG) was recorded during reactive stepping and non-stepping blocks, presented in a counterbalanced order. Analyses included event-related potentials, spectral dynamics, and graph theory approaches. Older adults showed delayed and reduced N100 responses compared to younger adults, with no differences between stepping conditions. Event-related spectral perturbations showed reduced post-perturbation theta and beta power synchronization in older adults. Network analysis indicated higher clustering coefficients and greater global efficiency in older adults compared to younger adults, particularly in the theta band. Similar early cortical activities across conditions suggest that perturbation-evoked responses are mainly driven by the detection of imbalance. These empirical results highlight the neural basis of age-related changes in postural adjustment, offering a potential outcome measure for targeted interventions.