Exploring muscular and postural correlates of the EEG-derived functional connectome during a quiet-standing stabilometric task.

Static postural control is a dynamic feedback process in which the integration of visual and somatosensory inputs within the central nervous system determines the activation of lower kinetic chain muscles, resulting in postural oscillations, to maintain balance during quiet standing. This study explored the association between cortical and muscular activity in relation to postural responses. Approach. Electroencephalography (EEG) is commonly used to assess neural oscillations. Network graph theory (NGT) applied to EEG-derived connectivity outlines the functional connectome. Surface electromyography (sEMG), combined with stabilogram analysis, enables the characterization of muscle activation patterns during postural control. By simultaneously acquiring EEG, sEMG and stabilometric signals, EEG-derived NGT metrics, sEMG-derived time- and frequency-domain features and sway parameters were correlated in twenty-one healthy volunteers (11 males, 29.52 ± 3.70 years) performing static postural control tasks for 30 seconds, standing upright on a stable surface, with eyes-closed (EC) and eyes-open (EO). Partial Spearman's rank correlation analyses were used to assess multimodal associations between NGT metrics and electromyographic and biomechanical measures. Main results. During EC sessions, changes in two postural sway measures (jerk, path length) were negatively correlated to changes in the resilience of the EEG connectome, as reconstructed from broadband EEG signals (P<0.05, corrected for multiple comparisons). During both EC and EO sessions, changes in muscle activation, fatigue-related and postural sway measures were weakly correlated to changes in multiple topological parameters of the EEG connectome, as reconstructed from either broadband (EC) or delta (EO), theta (EO), alpha (EO), beta (EO) and gamma (EC) EEG signals. Significance. This study highlights possible frequency-dependent associations between the global topological organization of the EEG functional connectome and muscular and postural responses during balance maintenance. Albeit preliminary, these exploratory findings may provide a novel perspective for the multimodal investigation of cortico-muscular interactions subserving postural control in health and disease.