The human sensorimotor cortex fosters muscle synergies through cortico-synergy coherence

Zandvoort, Coen S.; Dieën, Jaap H. van; Dominici, Nadia; Daffertshofer, Andreas

doi:10.1016/j.neuroimage.2019.05.041

Cited by 57 publications

(54 citation statements)

References 49 publications

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“…Several studies already revealed the phasic modulation of corticomuscular coherence ( Gwin et al, 2011 ; Gwin and Ferris, 2012 ; Roeder et al, 2018 ) and their importance of stabilizing modes of coordination ( Bruijn et al, 2015 ). Interestingly, a recent experiment by Zandvoort et al (2019) successfully identified cortical contributions to synergy formation by combining electroencephalography with EMG-based synergy analysis. Future work may adopt this approach to substantiate our suggestions about high-frequency, long-distant neural activation in the context of interlimb coordination and their sources in the central nervous system.…”

Section: Discussionmentioning

confidence: 99%

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Muscle Synergies and Coherence Networks Reflect Different Modes of Coordination During Walking

et al. 2020

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When walking speed is increased, the frequency ratio between the arm and leg swing switches spontaneously from 2:1 to 1:1. We examined whether these switches are accompanied by changes in functional connectivity between multiple muscles. Subjects walked on a treadmill with their arms swinging along their body while kinematics and surface electromyography (EMG) of 26 bilateral muscles across the body were recorded. Walking speed was varied from very slow to normal. We decomposed EMG envelopes and intermuscular coherence spectra using non-negative matrix factorization (NMF), and the resulting modes were combined into multiplex networks and analyzed for their community structure. We found five relevant muscle synergies that significantly differed in activation patterns between 1:1 and 2:1 arm-leg coordination and the transition period between them. The corresponding multiplex network contained a single module indicating pronounced muscle co-activation patterns across the whole body during a gait cycle. NMF of the coherence spectra distinguished three EMG frequency bands: 4–8, 8–22, and 22–60 Hz. The community structure of the multiplex network revealed four modules, which clustered functional and anatomical linked muscles across modes of coordination. Intermuscular coherence at 4–22 Hz between upper and lower body and within the legs was particularly pronounced for 1:1 arm-leg coordination and was diminished when switching between modes of coordination. These findings suggest that the stability of arm-leg coordination is associated with modulations in long-distant neuromuscular connectivity.

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Section: Discussionmentioning

confidence: 99%

“…and required λ (m) ≥ λ cutoff = 80% ( Zandvoort et al, 2019 ) and, additionally, λ (m) −λ ( m–1 ) ≥ Δλ cutoff = 1.5%. This notion let us also define the contribution of every synergy to the representation of W (m) A (m) by realizing that W (m) = [w 1 ,…, w m ] and A (m) = [ a 1 ,…, a m ].…”

Section: Methodsmentioning

confidence: 99%

Muscle Synergies and Coherence Networks Reflect Different Modes of Coordination During Walking

et al. 2020

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“…Despite the increasing number of studies investigating muscle synergies, the underlying mechanisms of muscle synergies remain unknown. It is still a topic of debate whether muscle synergies have a neural or non-neural origin (Bizzi and Cheung, 2013 ; Zandvoort et al, 2019 ). Muscle synergies in neonates were shown to mainly reflect spinal cord and brainstem activity, with an increase of the integration of supraspinal and sensory control during development (Dominici et al, 2011 ).…”

Section: Discussionmentioning

confidence: 99%

Muscle Synergies During Walking in Children With Cerebral Palsy: A Systematic Review

et al. 2020

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Background: Walking problems in children with cerebral palsy (CP) can in part be explained by limited selective motor control. Muscle synergy analysis is increasingly used to quantify altered neuromuscular control during walking. The early brain injury in children with CP may lead to a different development of muscle synergies compared to typically developing (TD) children, which might characterize the abnormal walking patterns. Objective: The overarching aim of this review is to give an overview of the existing studies investigating muscle synergies during walking in children with CP compared to TD children. The main focus is on how muscle synergies differ between children with CP and TD children, and we examine the potential of muscle synergies as a measure to quantify and predict treatment outcomes. Methods: Bibliographic databases were searched by two independent reviewers up to 22 April 2019. Studies were included if the focus was on muscle synergies of the lower limbs during walking, obtained by a matrix factorization algorithm, in children with CP. Results: The majority (n = 12) of the 16 included studies found that children with CP recruited fewer muscle synergies during walking compared to TD children, and several studies (n = 8) showed that either the spatial or temporal structure of the muscle synergies differed between children with CP and TD children. Variability within and between subjects was larger in children with CP than in TD children, especially in more involved children. Muscle synergy characteristics before treatments to improve walking function could predict treatment outcomes (n = 3). Only minimal changes in synergies were found after treatment. Conclusions: The findings in this systematic review support the idea that children with CP use a simpler motor control strategy compared to TD children. The use of muscle synergy analysis as a clinical tool to quantify altered neuromuscular control and predict clinical outcomes seems promising. Further investigation on this topic is necessary, and the use of muscle synergies as a target for development of novel therapies in children with CP could be explored.

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“…The modulation of CC and GE with HAL also suggests modulated control of muscles by the central nervous system during walking with HAL. Recent studies on the cortical control of muscle synergies discuss that beta-band frequency (13-30 Hz) and piper rhythm frequency (around 40 Hz) are used for communication between the cortical networks and the spinal cord for the purpose of formation, control, and maintenance of muscle synergies (79,80). Our muscle network analysis used a frequency band of 22-44 Hz as the higher part of frequency band based on the PSD of each muscle.…”

Section: Discussionmentioning

confidence: 99%

Muscular Activity Modulation During Post-operative Walking With Hybrid Assistive Limb (HAL) in a Patient With Thoracic Myelopathy Due to Ossification of Posterior Longitudinal Ligament: A Case Report

et al. 2020

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Disorders of the central nervous system sometimes cause severe sensory motor paralysis accompanied by gait impairment. Recently, there are several reports on the effectiveness of robot-assisted gait training for patients experiencing these issues. The purpose of this case report was to assess the neuromechanical effect of a wearable robot suit HAL (Hybrid Assistive Limb) during post-operative gait training in a patient with gait impairment due to compressive myelopathy caused by ossification of the posterior longitudinal ligament (OPLL). For this purpose, we compared lower limb muscular activities while the patient was walking with and without the robot through a course of treatment sessions by (i) gait phase-dependent muscle usage analysis, (ii) muscle synergy analysis, and (iii) muscle network analysis. The results show (i) enhanced activity of the extensor muscles for weight-bearing in the initial sessions by using HAL and reduced knee extensor and increased hip extensor activations for achieving larger steps and faster gait in the later sessions; (ii) involvement of a greater number of synergies during walking with HAL than without HAL; and (iii) modulated muscle network property during walking with HAL remaining until the next HAL session. The patient's gait was improved after completing HAL sessions, acquiring close to normal joint profile with greater range of joint movement, faster walking speed, and larger step length. We discuss that the muscular activity modulation during walking with HAL suggests altered control of the muscles by the central nervous system during post-operative walking. Activity-dependent sensorimotor augmentation by HAL is discussed in the context of recovery of gait control by the central nervous system. The relationship between the altered control and the achieved gait recovery requires further investigation.

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The human sensorimotor cortex fosters muscle synergies through cortico-synergy coherence

Cited by 57 publications

References 49 publications

Muscle Synergies and Coherence Networks Reflect Different Modes of Coordination During Walking

Muscle Synergies and Coherence Networks Reflect Different Modes of Coordination During Walking

Muscle Synergies During Walking in Children With Cerebral Palsy: A Systematic Review

Muscular Activity Modulation During Post-operative Walking With Hybrid Assistive Limb (HAL) in a Patient With Thoracic Myelopathy Due to Ossification of Posterior Longitudinal Ligament: A Case Report

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