Muscle Synergies-Based Characterization and Clustering of Poststroke Patients in Reaching Movements

Scano, Alessandro; Chiavenna, Andrea; Malosio, Matteo; Tosatti, Lorenzo Molinari; Molteni, Franco

doi:10.3389/fbioe.2017.00062

Cited by 32 publications

(31 citation statements)

References 51 publications

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“…These differences were also robust to using a less stringent level of 80% of VAF criterion. The variance differences are consistent with observations that central nervous system (CNS) injury causes fewer synergies to be required, with possible merging and collapse of synergies (27,(33)(34)(35)(36)(37)(38)(39)(40). The reduced numbers of higher-variance synergies in the ATX group here, with merging or collapse of parts of the patterns as consequences, would reduce flexibility and generate motor deficits in the ATX group of rats compared with the NTX and INTACT rats.…”

Section: Resultssupporting

confidence: 85%

“…Second, some synergies were not altered in weights but instead, ceased to be used strongly in patterns. Both of these types of changes are likely significant in motor drive infrastructure, pattern generation, and the pathologies and injury effects where synergies may have impact (27,(33)(34)(35)(36)(37)(38)(39)(40)(44)(45)(46)(47)(48)(49). Synergies normally weakly activated in intact CNS that become active in disease would interfere with normal function and be pathological.…”

Section: Discussionmentioning

confidence: 99%

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Motor primitives are determined in early development and are then robustly conserved into adulthood

Yang

Logan

Giszter

2019

Proc. Natl. Acad. Sci. U.S.A.

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Motor patterns in legged vertebrates show modularity in both young and adult animals, comprising motor synergies or primitives. Are such spinal modules observed in young mammals conserved into adulthood or altered? Conceivably, early circuit modules alter radically through experience and descending pathways' activity. We analyze lumbar motor patterns of intact adult rats and the same rats after spinal transection and compare these with adult rats spinal transected 5 days postnatally, before most motor experience, using only rats that never developed hind limb weight bearing. We use independent component analysis (ICA) to extract synergies from electromyography (EMG). ICA information-based methods identify both weakly active and strongly active synergies. We compare all spatial synergies and their activation/drive strengths as proxies of spinal modules and their underlying circuits. Remarkably, we find that spatial primitives/synergies of adult injured and neonatal injured rats differed insignificantly, despite different developmental histories. However, intact rats possess some synergies that differ significantly, although modestly, in spatial structure. Rats injured as adults were more similar in modularity to rats that had neonatal spinal transection than to themselves before injury. We surmise that spinal circuit modules for spatial synergy patterns may be determined early, before postnatal day 5 (P5), and remain largely unaltered by subsequent development or weight-bearing experience. An alternative explanation but equally important is that, after complete spinal transection, both neonatal and mature adult spinal cords rapidly converge to common synergy sets. This fundamental or convergent synergy circuitry, fully determined by P5, is revealed after spinal cord transection.motor primitives | muscle synergies | pattern generation | spinal cord injury | development M otor patterns can show significant modularity in legged vertebrates. Modularity can take several forms (1). Here, we examine modular motor drives in spinal systems. This approach combines both structural and functional neural components. The fundamental idea is that basic movement is largely composed of small numbers of synergies or motor primitives, which act as building blocks (1-5). Synergies for this study are defined as spatial synergies (1), which each represent a premotor drive to motor pools, causing covarying muscle activity in a specific balance. Such drives could arise from a well-defined neural substrate of sets of neurons with specific premotor connectivity. Indeed, some data in frogs and monkeys support this idea (6, 7). Such modularity could arise as follows: first, directly through evolutionarily determined processes in development; second, through plastic online optimizations during development; third, de novo during motor skill learning; or fourth, via some combinations of these (1,2,4,8). The collection of synergies resulting from any of these processes can form a library of compositional elements useful both for new movement con...

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Section: Resultssupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Motor primitives are determined in early development and are then robustly conserved into adulthood

Yang

Logan

Giszter

2019

Proc. Natl. Acad. Sci. U.S.A.

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“…Similarly to the results reported in d'Avella et al [12,14,41], the first synergy is related to elbow flexion, while synergies 2-4 are related to elbow extension and shoulder flexion.…”

Section: Discussionsupporting

confidence: 87%

The Effects of Motor Modularity on Performance, Learning, and Generalizability in Upper-Extremity Reaching: a Computational Analysis

Borno

Hicks

Delp

2019

Preprint

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It has been hypothesized that the central nervous system simplifies the production of movement by limiting motor commands to a small set of modules known as muscle synergies. Recently, investigators have questioned whether a low-dimensional controller can produce the rich and flexible behaviors seen in everyday movements. We implemented * Corresponding author: malborno@stanford.edu controllers could also accomplish new tasks-such as reaching to targets on a higher or lower plane, starting from an alternate initial pose, moving at a faster velocity, and holding a light weight-with average errors similar to a full-dimensional controller. We also found that for new tasks, the synergybased controllers converged to good solutions (as defined by a cost-function threshold) with lower computational cost than a full-dimensional controller.Our results show that a modular architecture based on muscle synergies can generate a wide variety of reaching behaviors for a high-dimensional musculoskeletal system without a significant degradation in performance.

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“…In more compromised patients, synergies appear to modify their spatial components, by splitting or merging different motor modules [20]. In a recent study [21], it was found that spatial synergies may be partially related to the patient motor functionality, in a small population of post-stroke patients.…”

Section: Introductionmentioning

confidence: 99%

A Multiparameter Approach to Evaluate Post-Stroke Patients: An Application on Robotic Rehabilitation

et al. 2018

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Multidomain instrumental evaluation of post-stroke chronic patients, coupled with standard clinical assessments, has rarely been exploited in the literature. Such an approach may be valuable to provide comprehensive insight regarding patients’ status, as well as orienting the rehabilitation therapies. Therefore, we propose a multidomain analysis including clinically compliant methods as electroencephalography (EEG), electromyography (EMG), kinematics, and clinical scales. The framework of upper-limb robot-assisted rehabilitation is selected as a challenging and promising scenario to test the multi-parameter evaluation, with the aim to assess whether and in which domains modifications may take place. Instrumental recordings and clinical scales were administered before and after a month of intensive robotic therapy of the impaired upper limb, on five post-stroke chronic hemiparetic patients. After therapy, all patients showed clinical improvement and presented pre/post modifications in one or several of the other domains as well. All patients performed the motor task in a smoother way; two of them appeared to change their muscle synergies activation strategies, and most subjects showed variations in their brain activity, both in the ipsi- and contralateral hemispheres. Changes highlighted by the new multiparametric instrumental approach suggest a recovery trend in agreement with clinical scales. In addition, by jointly demonstrating lateralization of brain activations, changes in muscle recruitment and the execution of smoother trajectories, the new approach may help distinguish between true functional recovery and the adoption of suboptimal compensatory strategies. In the light of these premises, the multi-domain approach may allow a finer patient characterization, providing a deeper insight into the mechanisms underlying the relearning procedure and the level (neuro/muscular) at which it occurred, at a relatively low expenditure. The role of this quantitative description in defining a personalized treatment strategy is of great interest and should be addressed in future studies.

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Muscle Synergies-Based Characterization and Clustering of Poststroke Patients in Reaching Movements

Cited by 32 publications

References 51 publications

Motor primitives are determined in early development and are then robustly conserved into adulthood

Motor primitives are determined in early development and are then robustly conserved into adulthood

The Effects of Motor Modularity on Performance, Learning, and Generalizability in Upper-Extremity Reaching: a Computational Analysis

A Multiparameter Approach to Evaluate Post-Stroke Patients: An Application on Robotic Rehabilitation

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