The Features of Synergetic Interaction of Skeletal Muscles of the Lower Extremities under Spinal Cord Electrical Stimulation

• Published in: Human physiology Vol. 49; no. 1; pp. 65 - 76
• Main Authors: Moiseev, S. A., Gorodnichev, R. M.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.02.2023; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Biomedicine; Electrical stimuli; Human Physiology; Life Sciences; Locomotor activity; Neural networks; Skeletal muscle; Spinal cord; spinal cord electrical stimulation; muscle synergies; motor control; locomotion; neural networks
• ISSN: 0362-1197; 1608-3164
• DOI: 10.1134/S0362119722600333

The aim of the study was to analyze the neural basis of the synergetic interaction of the skeletal muscles of the lower extremities during locomotor activity. It was supposed to determine the relationship of the locomotor-related neuronal networks with the centers regulating the spatiotemporal modes of muscle interaction in the structure of the step cycle and its phases. The subjects walked the treadmill both under normal conditions and during percutaneous spinal cord electrical stimulation at T11–T12 and L1–L2 levels within certain phases of the step cycle. The parameters of the synergies extracted using the principal component method were analyzed. Under the influence of stimulation, a significant decrease in the number of extracted “amplitude” synergies in the structure of the step cycle and the swing phase, as well as a decrease in the number of “frequency” synergies in the stance phase, was established. A clear differentiation of the synergistic activity of the muscles of both legs in the first two synergies was noted, and under stimulation, a change in the contribution of the activity of the gastrocnemius, anterior tibial, and lateral vastus muscles to the first two synergies was observed, mainly in the swing phase. The synergy structure demonstrated combined temporal profiles with several peaks of activity. During stimulation, the formation of a basic profile with a clear outline of the main fluctuations was revealed. The spatiotemporal structure of muscle synergy patterns during the stance phase turned out to be more stable, which is probably due to an increase in afferentations from the foot support-sensitive zones, which creates optimal conditions for initiating the central generators of locomotor pattern.