Effect of upright standing postures on cortical oscillation spectral power modulations

Abstract

Introduction Amplitude modulation of cortical oscillations are associated to various movement parameters. Recently, theta-band cortical oscillations were shown to be involved in maintaining upright posture. However, the function of delta-, alpha-, beta-, and gamma-band cortical oscillatory components still needs to be clarified. To provide further understanding of the function of cortical oscillations in controlling balance, we investigated the effect of different upright standing postures on the modulation of cortical oscillations. Materials and methods Brain activity and ground reaction forces of 13 participants were recorded using 64 electroencephalographic electrodes and a force platform. Participants stood upright in four conditions: with regular and narrow stance widths and on firm and foam surfaces. To obtain modulation of cortical oscillations, brain activity was also recorded while sitting on a chair. Modulation of cortical oscillation spectral power and the confidence ellipse area of the center of pressure displacement were compared between stance widths and surfaces using a linear mixed model. Results Confidence ellipse area significantly increased during the narrow and the foam conditions. Delta-band synchronization significantly increased in the central region during foam and narrow conditions. In all conditions, alpha- and beta-band showed desynchronization in the central region. Additionally, alpha-band showed desynchronization in frontal and occipital regions, which was significantly greater during narrow stance conditions. Finally, gamma-band synchronization significantly increased in the right temporoparietal junction during narrow and foam conditions. Discussion/conclusion Alpha- and beta-band desynchronization as well as delta- and gamma-band synchronization and their modulations during unstable postural conditions highlight the involvement of these cortical oscillatory components in balance control.