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Koh K, Oppizzi G, Kehs G, Zhang LQ. Abnormal coordination of upper extremity during target reaching in persons post stroke. Sci Rep 2023; 13:12838. [PMID: 37553412 PMCID: PMC10409717 DOI: 10.1038/s41598-023-39684-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 07/28/2023] [Indexed: 08/10/2023] Open
Abstract
Understanding abnormal synergy of the upper extremity (UE) in stroke survivors is critical for better identification of motor impairment. Here, we investigated to what extent stroke survivors retain the ability to coordinate multiple joints of the arm during a reaching task. Using an exoskeleton robot, 37 stroke survivors' arm joint angles (θ) and torques (τ) during hand reaching in the horizontal plane was compared to that of 13 healthy controls. Kinematic and kinetic coordination patterns were quantified as variances of the multiple-joint angles and multiple-joint torques across trials, respectively, that were partitioned into task-irrelevant variance (TIVθ and TIVτ) and task-relevant variance (TRVθ and TRVτ). TIVθ and TRVθ (or TIVτ and TRVτ) led to consistent and inconsistent hand position (or force), respectively. The index of synergy (ISθ and ISτ) was determined as [Formula: see text] and [Formula: see text] for kinematic and kinetic coordination patterns, respectively. Both kinematic ISθ and kinetic ISτ in the stroke group were significantly lower than that of the control group, indicating stroke survivors had impaired reaching abilities in utilizing the multiple joints of the UE for successful completion of a reaching task. The reduction of kinematic ISθ in the stroke group was mainly attributed to the lower TIVθ as compared to the control group, while the reduction of kinetic ISτ was mainly due to the higher [Formula: see text] as well as lower TIVτ. Our results also indicated that stroke may lead to motor deficits in formation of abnormal kinetic synergistic movement of UE, especially during outward movement. The findings in abnormal synergy patterns provides a better understanding of motor impairment, suggesting that impairment-specific treatment could be identified to help improve UE synergies, focusing on outward movements.
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Affiliation(s)
- Kyung Koh
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, 20742, USA
| | - Giovanni Oppizzi
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, 20742, USA
- Department of Physical Therapy and Rehabilitation Science, University of Maryland, 100 Penn St, Baltimore, MD, 21201, USA
| | - Glenn Kehs
- University of Maryland Rehabilitation and Orthopaedic Institute, Baltimore, MD, 21207, USA
- Department of Neurology, University of Maryland, Baltimore, MD, 21201, USA
| | - Li-Qun Zhang
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, 20742, USA.
- Department of Physical Therapy and Rehabilitation Science, University of Maryland, 100 Penn St, Baltimore, MD, 21201, USA.
- Department of Orthopaedics, University of Maryland, Baltimore, MD, 21201, USA.
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Honarvar S, Caminita M, Ehsani H, Kwon HJ, Diaz-Mercado Y, Hahn JO, Kiemel T, Shim JK. Interpersonal motor synergy: coworking strategy depends on task constraints. J Neurophysiol 2021; 126:1698-1709. [PMID: 34644124 DOI: 10.1152/jn.00023.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the role of task constraints on interpersonal interactions. Twenty-one pairs of coworkers performed a finger force production task on force sensors placed at two ends of a seesaw-like apparatus and matched a combined target force of 20 N for 23 s over 10 trials. There were two experimental conditions: 1) FIXED: the seesaw apparatus was mechanically held in place so that the only task constraint was to match the 20 N resultant force, and 2) MOVING: the lever in the apparatus was allowed to rotate freely around its fulcrum, acting like a seesaw, so an additional task constraint to (implicitly) balance the resultant moment was added. We hypothesized that the additional task constraint of moment stabilization imposed on the MOVING condition would deteriorate task performance compared with the FIXED condition; however, this was rejected, as the performance of the force matching task was similar between two conditions. We also hypothesized that the central nervous systems (CNSs) would employ distinct coworking strategies or interpersonal motor synergy (IPMS) between conditions to satisfy different task constraints, which was supported by our results. Negative covariance between coworker's forces in the FIXED condition suggested a force stabilization strategy, whereas positive covariance in the MOVING condition suggested a moment stabilization strategy, implying that independent CNSs adopt distinct IPMSs depending on task constraints. We speculate that in the absence of a central neural controller, shared visual and mechanical connections between coworkers may suffice to trigger modulations in the cerebellum of each CNS to satisfy competing task constraints.NEW & NOTEWORTHY To the best of our knowledge, this is the first study to investigate the coworking behavior or IPMS when an additional task constraint is imposed. Our proposed analytical framework quantifies IPMS and allows for investigating variability in offline (i.e., across multiple repetitions) and online (i.e., across time) control, which is novel in coworking research. Understanding variability while performing a task is essential, as repeating a task is not always possible, as in therapeutic contexts.
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Affiliation(s)
- Sara Honarvar
- Department of Kinesiology, University of Maryland, College Park, Maryland.,Department of Mechanical Engineering, University of Maryland, College Park, Maryland
| | - Mia Caminita
- Department of Kinesiology, University of Maryland, College Park, Maryland
| | - Hossein Ehsani
- Department of Kinesiology, University of Maryland, College Park, Maryland
| | - Hyun Jun Kwon
- Department of Kinesiology, University of Maryland, College Park, Maryland
| | - Yancy Diaz-Mercado
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland
| | - Jin-Oh Hahn
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland
| | - Tim Kiemel
- Department of Kinesiology, University of Maryland, College Park, Maryland.,Program in Neuroscience & Cognitive Science, University of Maryland, College Park, Maryland
| | - Jae Kun Shim
- Department of Kinesiology, University of Maryland, College Park, Maryland.,Department of Mechanical Engineering, University of Maryland, College Park, Maryland.,Program in Neuroscience & Cognitive Science, University of Maryland, College Park, Maryland.,Department of Mechanical Engineering, Kyung Hee University, Yongin-si, South Korea
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Koh K, Park YS, Park DW, Shim JK. Dance training improves the CNS's ability to utilize the redundant degrees of freedom of the whole body. Sci Rep 2020; 10:22197. [PMID: 33335153 PMCID: PMC7747644 DOI: 10.1038/s41598-020-79081-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 11/30/2020] [Indexed: 11/09/2022] Open
Abstract
Professional dancers demonstrate an amazing ability to control their balance. However, little is known about how they coordinate their body segments for such superior control. In this study, we investigated how dancers coordinate body segments when a physical perturbation is given to their body. A custom-made machine was used to provide a short pulling impulse at the waist in the anterior direction to ten dancers and ten non-dancers. We used Uncontrolled Manifold analysis to quantify the variability in the task-relevant space and task-irrelevant space within the multi-dimensional space made up of individual segments’ centers of mass with a velocity adjustment. The dancers demonstrated greater utilization of redundant degrees of freedom (DoFs) supported by the greater task-irrelevant variability as compared to non-dancers. These findings suggest that long-term specialized dance training can improve the central nervous system’s ability to utilize the redundant DoFs in the whole-body system.
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Affiliation(s)
- Kyung Koh
- Department of Kinesiology, University of Maryland, College Park, MD, USA.,Department of Physical Therapy and Rehabilitation Science, University of Maryland, Baltimore, MD, USA
| | - Yang Sun Park
- Department of Sports Welfare, Korea National University of Transportation, Chungcheongbuk-do, South Korea.
| | - Da Won Park
- Department of Kinesiology, Seoul National University, Seoul, South Korea
| | - Jae Kun Shim
- Department of Kinesiology, University of Maryland, College Park, MD, USA. .,Department of Mechanical Engineering, Kyung Hee University, Yongin-Si, Gyeonggi-do, South Korea. .,Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD, USA. .,Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.
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