Influence of neuromuscular electrical stimulation pulse waveform on corticomuscular coupling and the brain functional connectivity network

Abstract

ObjectiveNeuromuscular electrical stimulation (NMES) has been shown to promote functional corticomuscular coupling (FCMC), but its effect on brain functional connectivity network (BFCN) remains uncertain. This study aims to propose a new method to analyze the influence of NMES with different stimulation waveforms on the motor system from two perspectives of FCMC and BFCN. ApproachThe bivariate empirical mode decomposition time-delay maximal information coefficient (BTDMIC) method was used to assess the local frequency band characteristics of the cortex and muscle. Main resultThe experimental results showed that the FCMC increment after NMES was prominent in the β1 (15–25 Hz), β2 (25–35 Hz), and γ1 (35–45 Hz) bands. Additionally, the coupling values of C3 after sine-NMES were highest in the β1 band, while the coupling values after square-NMES were highest in the β2 and γ1 bands. For BFCN, the cortical-cortical coupling of the C3 after square-NMES was high in the C3 → others direction. Moreover, in the α (8–14 Hz) and β1 bands, the clustering coefficient, density, and efficiency after square-NMES were significantly higher than those of the three other frequency bands. ConclusionNMES effectively promoted information exchange between the motor cortices of the brain, and the facilitating effect is particularly pronounced in the case of square-NMES. SignificanceThis study offers a novel perspective for evaluating rehabilitation therapies based on NMES.