Practical assessment of motor preparation–execution coupling during active ankle dorsiflexion in post-stroke gait: A pilot study

Objective: Active ankle dorsiflexion (AAD) has been proposed as a surrogate measure for gait-related motor control. However, whether the neural coupling between motor preparation and execution during AAD predicts gait ability remains unclear. This study examined whether μ-γ coupling was evaluated as a practical neurophysiological marker of gait performance. Methods: In this study, 12 healthy adults and 4 patients with chronic stroke performed an AAD task and an overground walking task. Ankle kinematics, surface electromyography, and electroencephalography were simultaneously recorded. Corticomuscular coherence (CMC) and phase-amplitude coupling (PAC) were analyzed as indices of motor preparation-execution coupling. Gait performance was assessed based on gait speed and a Gait Assessment and Intervention Tool (G.A.I.T.). Results: Patients with stroke showed significantly lower gait speed (0.60 vs. 1.24 m/s, p < 0.001) and G.A.I.T. scores compared to controls. In the AAD task, patients with stroke exhibited significantly reduced ankle angular velocity and lower CMC between Cz and the tibialis anterior compared to controls (p < 0.05). Source localization revealed diminished activity in the middle temporal gyrus, inferior parietal lobule, and insula in patients with stroke. Notably, the PAC-derived modulation index (MI) at Cz was markedly reduced in patients with stroke (0.03) compared to controls (1.50, p < 0.001), clearly discriminating between the groups. Conclusions & significance: Motor preparation-execution coupling during AAD strongly reflects gait capacity after stroke. PAC-MI is a novel neurophysiological marker; requires validation biomarker for the early and objective evaluation of gait-related motor control with potential utility in stroke rehabilitation.