Worse balance is associated with larger perturbation-evoked cortical responses in healthy young adults

• Type of Material: Article
• Authors: Aiden M. Payne, Georgia Tech; Lena Ting, Emory University
• Language: English
• Date: 2020-07-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: 2020 The Author(s). Published by Elsevier B.V
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): https://www.sciencedirect.com/science/article/pii/S0966636220302198?via%3Dihub
• Title of Journal or Parent Work: GAIT & POSTURE
• Volume: 80
• Start Page: 324
• End Page: 330
• Grant/Funding Information: This work was supported by the National Institutes of Health (5T90DA032466, 1P50NS098685, and R01 HD46922-10), the National Science Foundation (1137229), and the Andy Zebrowitz Memorial Brain Research Fellowship Award (2017-2018).
• Keywords: Posture; motor skill; EEG; Walking balance; N1
• Research Categories: Biology, Neuroscience; Health Sciences, Human Development

Abstract

Background: Reactive balance recovery evokes a negative peak of cortical electroencephalography (EEG) activity (N1) that is simultaneous to brainstem-mediated automatic balance-correcting muscle activity. This study follows up on an observation from a previous study, in which N1 responses were larger in individuals who seemed to have greater difficulty responding to support-surface perturbations. Research Question: We hypothesized that people engage more cortical activity when balance recovery is more challenging. We predicted that people with lower balance ability would exhibit larger cortical N1 responses during balance perturbations. Methods: In 20 healthy young adults (11 female, ages 19–38) we measured the amplitude of the cortical N1 response evoked by 48 backward translational support-surface perturbations of unpredictable timing and amplitude. Perturbations included a Small (8 cm) perturbation that was identical across participants, as well as Medium (13–15 cm) and Large (18–22 cm) perturbations scaled to participant height to control for height-related differences in perturbation difficulty. To assess individual differences in balance ability, we measured the distance traversed on a narrow (0.5-inch wide) 12-foot beam across 6 trials. We tested whether the cortical N1 response amplitude was correlated to balance ability across participants. Results: Cortical N1 amplitudes in response to standing balance perturbations (54 ± 18 μV) were inversely correlated to the distance traveled in the difficult beam-walking task (R2 = 0.20, p = 0.029). Further, there was a significant interaction between performance on the beam-walking task and the effect of perturbation magnitude on the cortical N1 response amplitude, whereby individuals who performed worse on the beam-walking task had greater increases in N1 amplitudes with increases in perturbation magnitude. Significance: Cortical N1 response amplitudes may reflect greater cortical involvement in balance recovery when challenged. This increased cortical involvement may reflect cognitive processes such as greater perceived threat or attention to balance, which have the potential to influence subsequent motor control.