Differential Cortical Activations Among Young Adults Who Fall Versus Those Who Recover Successfully Following an Unexpected Slip During Walking

Abstract

Background: Biomechanical and neuromuscular differences between falls and recoveries have been well-studied; however, the cortical correlations remain unclear. Using mobile brain imaging via electroencephalography (EEG), we examined differences in sensorimotor beta frequencies between falls and recoveries during an unpredicted slip in walking. Methods: We recruited 22 young adults (15 female; 18-35 years) who experienced a slip (65 cm) during walking. Raw EEG signals were band-pass filtered, and independent component analysis was performed to remove non-neural sources, eventually three participants were excluded due to excessive artifacts. Peak beta power was extracted from three time-bins: 400 milliseconds pre-, 0-150 milliseconds post and 150-300 milliseconds post-perturbation from the midline (Cz) electrode. A 2 × 3 Analysis of Covariance assessed the interaction between time-bins and group on beta power, followed by Independent and Paired t-tests for between and within-group post hoc comparisons. Results: All participants (n = 19) experienced a balance loss, seven experienced a fall. There was a time × group interaction on beta power (p < 0.05). With no group differences pre-perturbation, participants who experienced a fall exhibited higher beta power during 0-150 milliseconds post-perturbation than those who recovered (p < 0.001). However, there were no group differences in beta power during 150-300 milliseconds post-perturbation. Conclusions: Young adults exhibiting a greater increase in beta power during the early post-perturbation period experienced a fall, suggesting a higher cortical error detection due to a larger mismatch in the expected and ongoing postural state and greater cortical dependence for sensorimotor processing. Our study results provide an overview of the possible cortical governance to modulate slip-fall/recovery outcomes.

Keywords: beta power; cerebral cortex; falls; sensorimotor processing; slip.

Figure 1

Box plots and individual data points representing the distribution of peak beta power focused at the Cz electrode between two groups: falls (n = 7) and successful recoveries (n = 12) and three time points: pre-perturbation onset (Pre-PO), i.e., 400 milliseconds before perturbation onset and early post-perturbation onset (post-PO), i.e., 0–150 milliseconds after and late post-perturbation onset (post-PO), i.e., 150–300 milliseconds after. Between groups, significant differences are represented as * for p < 0.05; significant differences at different time points within-groups are represented as ## for p < 0.01. Abbreviations: PO—Perturbation onset, dB—Decibel (units for beta power).

Figure 2

Event-related spectral perturbations (ERSPs) focused at the Cz electrode in the beta frequency range (13–30 Hz) for two representative participants who experienced: (a) A Fall and (b) A Recovery following an unpredicted slip during walking. (a) shows a sharp increase in power (dB) throughout the beta frequency range (13–30 Hz), whereas (b) shows a modest increase in power (dB) throughout the beta frequency range. Notably, pre-perturbation beta power is visible similarly across the beta frequency range. Abbreviations: PO (Perturbation onset), LO (Lift-off) of the recovery limb, and TD (Touchdown) of the recovery limb.