Balance task difficulty affects postural sway and cortical activity in healthy adolescents

Abstract

Electroencephalographic (EEG) research indicates changes in adults' low frequency bands of frontoparietal brain areas executing different balance tasks with increasing postural demands. However, this issue is unsolved for adolescents when performing the same balance task with increasing difficulty. Therefore, we examined the effects of a progressively increasing balance task difficulty on balance performance and brain activity in adolescents. Thirteen healthy adolescents aged 16-17 year performed tests in bipedal upright stance on a balance board with six progressively increasing levels of task difficulty. Postural sway and cortical activity were recorded simultaneously using a pressure sensitive measuring system and EEG. The power spectrum was analyzed for theta (4-7 Hz) and alpha-2 (10-12 Hz) frequency bands in pre-defined frontal, central, and parietal clusters of electrocortical sources. Repeated measures analysis of variance (rmANOVA) showed a significant main effect of task difficulty for postural sway (p < 0.001; d = 6.36). Concomitantly, the power spectrum changed in frontal, bilateral central, and bilateral parietal clusters. RmANOVAs revealed significant main effects of task difficulty for theta band power in the frontal (p < 0.001, d = 1.80) and both central clusters (left: p < 0.001, d = 1.49; right: p < 0.001, d = 1.42) as well as for alpha-2 band power in both parietal clusters (left: p < 0.001, d = 1.39; right: p < 0.001, d = 1.05) and in the central right cluster (p = 0.005, d = 0.92). Increases in theta band power (frontal, central) and decreases in alpha-2 power (central, parietal) with increasing balance task difficulty may reflect increased attentional processes and/or error monitoring as well as increased sensory information processing due to increasing postural demands. In general, our findings are mostly in agreement with studies conducted in adults. Similar to adult studies, our data with adolescents indicated the involvement of frontoparietal brain areas in the regulation of postural control. In addition, we detected that activity of selected brain areas (e.g., bilateral central) changed with increasing postural demands.

Effects of balance training on balance performance in youth: role of training difficulty

“…Additionally, following 6 weeks of balance training on an unstable surface (i.e., slackline) Giboin et al [ 23 ] reported decreased H-reflex amplitudes during stepping on a slackline indicating a more anticipatory/feedforward organization of postural control. Another explanation relates to the central nervous plane [ 24 – 27 ]. For example, Gebel et al [ 24 ] used electroencephalographic analyses to examine the impact of increasing balance task difficulty on cortical activity in adolescents.…”

“…Another explanation relates to the central nervous plane [ 24 – 27 ]. For example, Gebel et al [ 24 ] used electroencephalographic analyses to examine the impact of increasing balance task difficulty on cortical activity in adolescents. They observed significant increases in the theta frequency band power and decreases in the alpha-2 frequency band power with increasing levels of task difficulty.…”

Stance leg and surface stability modulate cortical activity during human single leg stance

“…Analysis of alpha power during the experimental conditions indicated a decrease in alpha-1 and alpha-2 power from stable to unstable conditions. Previous investigations associated these desynchronizations in alpha power with task-specific sensorimotor processing to counteract postural instability (Del Percio et al 2009 ; Hülsdünker et al 2015 ; Gebel et al 2020 ). Accordingly, the present study demonstrated that spectral power in the alpha-1 and alpha-2 frequency band significantly decreased in bilateral motor and right parieto-occipital clusters with increased postural instability.…”

“…In the present investigation, the observed increased body sway demonstrated that the postural equilibrium was perturbed by the unstable base of support, leading to increased error detection and processing. Therefore, it maybe speculated that the increase in fronto-midline theta power along with increased postural sway may represent higher attentional demands and error processing to control for postural equilibrium (Fournier et al 1999 ; Slobounov et al 2009 ; Sipp et al 2013 ; Gebel et al 2020 ).…”

“…Various neuroimaging studies have already demonstrated that the brain may actively contribute to postural stability in response to changing sensorimotor demands (Mierau et al 2017 ; Solis-Escalante et al 2019 ; Varghese et al 2019 ; Gebel et al, 2020 ). In conditions with modulations to the base of support, previous findings have revealed increased cortical activity in frontal (Tse et al 2013 ; Hülsdünker et al 2015 ), motor (Varghese et al, 2015 ), parietal (Hülsdünker et al, 2016a ) and occipital cortical areas (Ouchi et al 1999 ; Slobounov et al 2009 ).…”