Task-Dependent Cortico-Spinal Coupling in the Delta Band During Movement Execution and Inhibitory Control.

Abstract

This study aimed to investigate cortico-spinal interactions during movement execution 'Go' and movement inhibition 'NoGo', with a focus on frequency-specific coupling between cortical activities and spinal motor neuron discharges. High-density surface EMG (HD-sEMG) was recorded from the right fore arm muscles in 16 healthy adults, and the cumulative spike train (CST) of the active motor units was estimated using the spatial spike detection (SSD) method. Electroen cephalography (EEG) and CST signals were analyzed in the time-frequency domain, andtheir couplings were assessed with the coherence and cross-correlation functions over three task-related time windows (steady phase, preparation, execution/inhibition). We observed a strong δ-band coupling between EEG and CST during movement execution, a phenomenon absent in the 'NoGo' condition. This effect was most pronounced during the movement execution window and localized at the contralateral senso rimotor cortex. By contrast, high-frequency coherence exhibited lateralization but showed no significant differences among the three task-related time windows in 'Go' and 'NoGo' conditions. These findings revealed that δ-band cortico-spinal couplings were specifically as sociated with rapid movement execution, whereas high frequency activities primarily reflected force maintenance. By combining EEG and SSD-based CST estimation, this study highlights the critical role of δ-band cortico-spinal coupling in rapid motor control and provide a potential neurophysiological indicator for assessing cortico-spinal tract integrity during functional motor tasks.