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Motor Control After Human SCI Through Activation of Muscle Synergies Under Spinal Cord Stimulation

Cheng, Richard and Sui, Yanan and Sayenko, Dimitry and Burdick, Joel W. (2019) Motor Control After Human SCI Through Activation of Muscle Synergies Under Spinal Cord Stimulation. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 27 (6). pp. 1331-1340. ISSN 1534-4320.

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Spinal cord stimulation (SCS) has enabled motor recovery in paraplegics with motor complete spinal cord injury (SCI). However, the physiological mechanisms underlying this recovery are unknown. This paper analyzes muscle synergies in two motor complete SCI patients under SCS during standing and compares them with muscle synergies in healthy subjects, in order to help elucidate the mechanisms that enable motor control through SCS. One challenge is that standard muscle synergy extraction algorithms, such as non-negative matrix factorization (NMF), fail when applied to SCI patients under SCS. We develop a new algorithm–rShiftNMF–to extract muscle synergies in these cases. We find muscle synergies extracted by rShiftNMF are significantly better at interpreting electromyography (EMG) activity, and resulting synergy features are more physiologically meaningful. By analyzing muscle synergies from SCI patients and healthy subjects, we find that: 1) SCI patients rely significantly on muscle synergy activation to generate motor activity; 2) interleaving SCS can selectively activate an additional muscle synergy that is critical to SCI standing; and 3) muscle synergies extracted from SCI patients under SCS differ substantially from those extracted from healthy subjects. We provide evidence that after spinal cord injury, SCS influences motor function through muscle synergy activation.

Item Type:Article
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URLURL TypeDescription
Cheng, Richard0000-0001-8301-9169
Sui, Yanan0000-0002-9480-627X
Additional Information:© 2019 IEEE. Manuscript received November 20, 2018; revised March 20, 2019; accepted April 17, 2019. Date of publication May 2, 2019; date of current version June 6, 2019. This work was supported by the National Institute of Health (NIH) under Grant EB007615. The authors thank Enrico Rejc, Claudia Angeli, and Susan Harkema for collecting and sharing the SCI dataset.
Funding AgencyGrant Number
Subject Keywords:Muscle synergy, spinal cord stimulation (SCI), spinal cord injury (SCI), matrix factorization, electromyography (EMG)
Issue or Number:6
Record Number:CaltechAUTHORS:20190617-151019077
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Official Citation:R. Cheng, Y. Sui, D. Sayenko and J. W. Burdick, "Motor Control After Human SCI Through Activation of Muscle Synergies Under Spinal Cord Stimulation," in IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 27, no. 6, pp. 1331-1340, June 2019. doi: 10.1109/TNSRE.2019.2914433
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96480
Deposited By: Tony Diaz
Deposited On:17 Jun 2019 22:32
Last Modified:03 Oct 2019 21:22

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