3. Fundamental Approaches of Studying the Neural Origin of Muscle Synergy

This chapter focuses on the neural basis of muscle synergy in the context of motor neuroscience. It discusses the historical significance of the concept and the contributions of both spinal circuitry and supraspinal regions in controlling muscle synergies. Despite substantial evidence and advancements in muscle synergy theory, alternate theoretical and methodological viewpoints in this field have also emerged, such as the UCM hypothesis and the EP hypothesis. The chapter also highlights the work of Nikolai Aleksandrovich Bernstein, a pioneer in muscle synergy research, and explores his extensive model that relates human coordination, kinematic degrees of freedom, and motor redundancy. The chapter further examines the influence of factors like aging, fatigue, and sports training on muscle synergies and introduces three popular dimensionality reduction techniques used in identifying patterns within muscle synergies. These techniques have applications in diverse fields such as spinal transection, stroke rehabilitation, gesture recognition, bio-robotics, and more.