Anodal transcranial direct current stimulation enhances ankle force control and modulates the beta-band activity of the sensorimotor cortex

Abstract

This study aimed to investigate the cortical responses to the ankle force control and the mechanism underlying changes in ankle force control task induced by transcranial direct current stimulation (tDCS). Sixteen young adults were recruited, and they completed the electroencephalogram (EEG) assessment and high-definition tDCS (HD-tDCS) sessions. Root mean square (RMS) error was used to evaluate ankle force control task performance. Spectral power analysis was conducted to extract the average power spectral density (PSD) in the alpha (8–13 Hz) and beta (13–30 Hz) bands for resting state and tasking (i.e. task-PSD). The ankle force control task induced significant decreases in alpha and beta PSDs in the central, left, and right primary sensorimotor cortex (SM1) and beta PSD in the central frontal as compared with the resting state. HD-tDCS significantly decreased the RMS and beta task-PSD in the central frontal and SM1. A significant association between the percent change of RMS and the percent change of beta task-PSD in the central SM1 after HD-tDCS was observed. In conclusion, ankle force control task activated a distributed cortical network mainly including the SM1. HD-tDCS applied over SM1 could enhance ankle force control and modulate the beta-band activity of the sensorimotor cortex.

Effects of tDCS on Foot Biomechanics: A Narrative Review and Clinical Applications

“…Appropriate force control of the ankle requires the proper functioning of baroreceptors and the regulation of cortical networks of the brain [ 51 ]. A single session of HD-tDCS applied over SM1 enhanced force control by modulating the beta-band activity of the sensorimotor cortex [ 23 ]. Moreover, tDCS can modulate cortical excitability to influence the neuromuscular reflex, eventually altering the reaction time for dorsiflexion [ 25 ].…”

“…tDCS also modulated corticospinal excitability in the lower limb region of the motor cortex and enhanced foot biomechanical performance [ 24 , 27 ]. Our recent findings suggested that participants exhibited a greater average percent decrease in beta task-related power spectral density (i.e., greater cortical activation) following a greater percent reduction in the root mean square of force control task (i.e., greater improvement in ankle force control task) after application of HD-tDCS; hence, HD-tDCS could modulate beta-band brain activity to improve ankle force control task [ 23 ]. Regarding improvements in foot neuro-biomechanical function, existing research suggests that tDCS primarily enhances excitability in the primary sensory cortex (S1).…”