Brain Processing During Postural Control – A Study Case

Abstract

In humans, postural control is naturally unstable and is considered to be a complex motor skill derived from the interaction of multiple sensorimotor processes to maintain postural orientation. This is a case study based results from a previous research performed on a large cohort [1]. From a technological point of view, the aim is to characterize the cortical responses associated with abrupt balance perturbations (adaptation) and changes in cortical activity during prolonged postural control (habituation). Also, to compare the cortical activity with the mechanical body sway performance during a balance task. Proprioceptive vibratory stimulation on calf muscles at 85 Hz was performed to evoke postural perturbation in a closed-eye experimental trial. Thirty seconds of quiet stance (baseline) and 225 s of random vibratory stimulation phases were divided into three epochs of 75 s each, with the impulses synchronized to EEG recording, using a 256-channel EEG cap and sampling rate of 1024 Hz. Channels shown to have statistically significant change in absolute power spectra variation were distinguished over six frequency bands (Δ, θ,α, β, low γ, and high γ). Force and torque actuated by the feet were recorded by a force platform and sampled at 50 Hz. A fluctuation index was computed to determine postural performance during the epochs. Results show a significant correlation between progress in platform performance and changes in cortical activity. The fluctuation indices decrease (indicating improvement in postural performance), and significant increase was found in absolute power values during adaptation phase in the parietal regions particularly in low gamma and thetaband.