Taking Food to Mouth: Correlation Between Repetitive Movement and Upper Limb Flexion Synergy After Stroke

BackgroundPathological upper-limb synergistic movement is a prevalent symptom of post-stroke motor dysfunction and pose a significant challenge in the rehabilitation of hemiplegia. However, the underlying mechanisms remain elusive, hindering the development of effective therapeutic strategies.ObjectiveThis study aims to explore the mechanisms underlying pathological synergic movements post-stroke by examining the interrelationship between motor modules associated with upper limb flexion synergy and the repetitive action of "taking food to the mouth."MethodsSurface electromyography (sEMG) was employed to capture the EMG signals of normal elbow flexion, the act of "taking food to the mouth," and post-stroke upper limb flexion synergy. Non-negative matrix factorization (NMF) was employed to compare and analyze the corresponding modular and coefficient matrices derived from these three motor tasks.ResultsThe modular matrix associated with flexion synergy exhibited the most significant correlation with the "taking food to the mouth" task, whereas the coefficient matrix shared the lowest correlation.ConclusionUpper limb flexion synergy after stroke may be related to the activation of the highly excitatory motor module formed by previously repeated movement of "taking food to mouth".