scholarly journals Assessing User Transparency with Muscle Synergies during Exoskeleton-Assisted Movements: A Pilot Study on the LIGHTarm Device for Neurorehabilitation

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Andrea Chiavenna ◽  
Alessandro Scano ◽  
Matteo Malosio ◽  
Lorenzo Molinari Tosatti ◽  
Franco Molteni
Keyword(s):  
Pilot Study ◽  
Upper Limb ◽  
Surface Electromyography ◽  
Healthy Subjects ◽  
Daily Life ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Gravity Compensation ◽  
Weight Support ◽  
Desirable Feature

Exoskeleton devices for upper limb neurorehabilitation are one of the most exploited solutions for the recovery of lost motor functions. By providing weight support, passively compensated exoskeletons allow patients to experience upper limb training. Transparency is a desirable feature of exoskeletons that describes how the device alters free movements or interferes with spontaneous muscle patterns. A pilot study on healthy subjects was conducted to evaluate the feasibility of assessing transparency in the framework of muscle synergies. For such purpose, the LIGHTarm exoskeleton prototype was used. LIGHTarm provides gravity support to the upper limb during the execution of movements in the tridimensional workspace. Surface electromyography was acquired during the execution of three daily life movements (reaching, hand-to-mouth, and hand-to-nape) in three different conditions: free movement, exoskeleton-assisted (without gravity compensation), and exoskeleton-assisted (with gravity compensation) on healthy people. Preliminary results suggest that the muscle synergy framework may provide valuable assessment of user transparency and weight support features of devices aimed at rehabilitation.

scholarly journals Upper-Limb Muscle Synergy Features in Human-Robot Interaction with Circle-Drawing Movements

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Cheng Wang ◽  
Shutao Zhang ◽  
Jingyan Hu ◽  
Zhejing Huang ◽  
Changcheng Shi
Keyword(s):  
Motor Function ◽  
Upper Limb ◽  
Healthy Subjects ◽  
Human Robot Interaction ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Robot Interaction ◽  
Rehabilitation Robots ◽  
Circle Drawing ◽  
Semg Signals

The upper-limb rehabilitation robots can be developed as an efficient tool for motor function assessments. Circle-drawing has been used as a specific task for robot-based motor function measurement. The upper-limb movement-related kinematic and kinetic parameters measured by motion and force sensors embedded in the rehabilitation robots have been widely studied. However, the muscle synergies characterized by multiple surface electromyographic (sEMG) signals in upper limbs during human-robot interaction (HRI) with circle-drawing movements are rarely investigated. In this research, the robot-assisted and constrained circle-drawing movements for upper limb were used to increase the consistency of muscle synergy features. Both clockwise and counterclockwise circle-drawing tasks were implemented by all healthy subjects using right hands. The sEMG signals were recorded from six muscles in upper limb, and nonnegative matrix factorization (NMF) analysis was utilized to obtain muscle synergy information. Both synergy pattern and activation coefficient were calculated to represent the spatial and temporal features of muscle synergies, respectively. The results obtained from the experimental study confirmed that high structural similarity of muscle synergies was found among the subjects during HRI with circle-drawing movement by healthy subjects, which indicates healthy people may share a common underlying muscle control mechanism during constrained upper-limb circle-drawing movement. This study indicates the muscle synergy analysis during the HRI with constrained circle-drawing movement could be considered as a task for upper-limb motor function assessment.

scholarly journals The effect of arm weight support on upper limb muscle synergies during reaching movements

2014 ◽  
Vol 11 (1) ◽  
pp. 22 ◽  
Author(s):  
Martina Coscia ◽  
Vincent CK Cheung ◽  
Peppino Tropea ◽  
Alexander Koenig ◽  
Vito Monaco ◽  
...  
Keyword(s):  
Upper Limb ◽  
Reaching Movements ◽  
Muscle Synergies ◽  
Limb Muscle ◽  
Weight Support ◽  
Arm Weight Support

scholarly journals A Comprehensive Spatial Mapping of Muscle Synergies in Highly Variable Upper-Limb Movements of Healthy Subjects

2019 ◽  
Vol 10 ◽  
Author(s):  
Alessandro Scano ◽  
Luca Dardari ◽  
Franco Molteni ◽  
Hermes Giberti ◽  
Lorenzo Molinari Tosatti ◽  
...  
Keyword(s):  
Upper Limb ◽  
Healthy Subjects ◽  
Spatial Mapping ◽  
Muscle Synergies ◽  
Limb Movements ◽  
Upper Limb Movements

scholarly journals Is the Neuromuscular Organization of Throwing Unchanged in Virtual Reality? Implications for Upper Limb Rehabilitation

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1495
Author(s):  
Emilia Scalona ◽  
Juri Taborri ◽  
Darren Richard Hayes ◽  
Zaccaria Del Prete ◽  
Stefano Rossi ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Healthy Subjects ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Virtual Reality Environment ◽  
Upper Limb Rehabilitation ◽  
Deceleration Phase ◽  
Research Challenge ◽  
Limb Rehabilitation ◽  
Non Negative Matrix Factorization

Virtual reality (VR) is an appealing approach for increasing the engagement and attention of patients during rehabilitation. Understanding how motor control changes in real vs. virtual scenarios is a research challenge in terms of validating its administration. This study evaluates muscle synergies when subjects conduct throwing tasks in virtual reality. Seventeen healthy subjects performed 20 throws both in a virtual environment and in real one as they threw a ball with both dominant and nondominant arms. The electromyography (EMG) signals of 11 muscles of the upper limbs were recorded. Non-negative matrix factorization was used to extract muscle synergies. The cosine similarity was computed to assess the consistence of muscle synergy organization between virtual and real tasks. The same parameter was used to establish the inter-subject similarity. A three-synergy model was selected as the most likely. No effects of virtual reality and arm side on neuromuscular organization were found. Forearm muscles, not necessary for ball holding and release, were comprised in the activation synergies in the virtual reality environment. Finally, the synergies were consistent across subjects, especially during the deceleration phase. Results are encouraging for the application of virtual reality to complement conventional therapy, improve engagement, and facilitate objective measurements of pathology progression.

scholarly journals Absence of postural muscle synergies for balance after spinal cord transection

2013 ◽  
Vol 110 (6) ◽  
pp. 1301-1310 ◽  
Author(s):  
Stacie A. Chvatal ◽  
Jane M. Macpherson ◽  
Gelsy Torres-Oviedo ◽  
Lena H. Ting
Keyword(s):  
Spinal Cord ◽  
Muscle Activity ◽  
Balance Control ◽  
Neural Mechanisms ◽  
Spinal Cord Transection ◽  
Muscle Synergy ◽  
Modular Organization ◽  
Muscle Synergies ◽  
Weight Support ◽  
Postural Muscle

Although cats that have been spinalized can also be trained to stand and step with full weight support, directionally appropriate long-latency responses to perturbations are impaired, suggesting that these behaviors are mediated by distinct neural mechanisms. However, it remains unclear whether these responses reflect an attenuated postural response using the appropriate muscular coordination patterns for balance or are due to fundamentally different neural mechanisms such as increased muscular cocontraction or short-latency stretch responses. Here we used muscle synergy analysis on previously collected data to identify whether there are changes in the spatial organization of muscle activity for balance within an animal after spinalization. We hypothesized that the modular organization of muscle activity for balance control is disrupted by spinal cord transection. In each of four animals, muscle synergies were extracted from postural muscle activity both before and after spinalization with nonnegative matrix factorization. Muscle synergy number was reduced after spinalization in three animals and increased in one animal. However, muscle synergy structure was greatly altered after spinalization with reduced direction tuning, suggesting little consistent organization of muscle activity. Furthermore, muscle synergy recruitment was correlated to subsequent force production in the intact but not spinalized condition. Our results demonstrate that the modular structure of sensorimotor feedback responses for balance control is severely disrupted after spinalization, suggesting that the muscle synergies for balance control are not accessible by spinal circuits alone. Moreover, we demonstrate that spinal mechanisms underlying weight support are distinct from brain stem mechanisms underlying directional balance control.

scholarly journals Muscle Synergies and Clinical Outcome Measures Describe Different Factors of Upper Limb Motor Function in Stroke Survivors Undergoing Rehabilitation in a Virtual Reality Environment

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 8002
Author(s):  
Lorenza Maistrello ◽  
Daniele Rimini ◽  
Vincent C. K. Cheung ◽  
Giorgia Pregnolato ◽  
Andrea Turolla
Keyword(s):  
Factor Analysis ◽  
Regression Model ◽  
Upper Limb ◽  
Motor Impairment ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Clinical Scales ◽  
Clinical Variables ◽  
Rehabilitation Protocols ◽  
General Linear Regression Model

Recent studies have investigated muscle synergies as biomarkers for stroke, but it remains controversial if muscle synergies and clinical observation convey the same information on motor impairment. We aim to identify whether muscle synergies and clinical scales convey the same information or not. Post-stroke patients were administered an upper limb treatment. Before (T0) and after (T1) treatment, we assessed motor performance with clinical scales and motor output with EMG-derived muscle synergies. We implemented an exploratory factor analysis (EFA) and a confirmatory factor analysis (CFA) to identify the underlying relationships among all variables, at T0 and T1, and a general linear regression model to infer any relationships between the similarity between the affected and unaffected synergies (Median-sp) and clinical outcomes at T0. Clinical variables improved with rehabilitation whereas muscle-synergy parameters did not show any significant change. EFA and CFA showed that clinical variables and muscle-synergy parameters (except Median-sp) were grouped into different factors. Regression model showed that Median-sp could be well predicted by clinical scales. The information underlying clinical scales and muscle synergies are therefore different. However, clinical scales well predicted the similarity between the affected and unaffected synergies. Our results may have implications on personalizing rehabilitation protocols.

scholarly journals Modular motor control of the sound limb in gait of people with trans-femoral amputation

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Cristiano De Marchis ◽  
Simone Ranaldi ◽  
Mariano Serrao ◽  
Alberto Ranavolo ◽  
Francesco Draicchio ◽  
...  
Keyword(s):  
Motor Control ◽  
Lower Limb ◽  
Muscle Activity ◽  
Healthy Subjects ◽  
Spatial Organization ◽  
Adaptation Strategy ◽  
Muscle Synergy ◽  
Heel Strike ◽  
Muscle Synergies ◽  
Control Schemes

Abstract Background The above-knee amputation of a lower limb is a severe impairment that affects significantly the ability to walk; considering this, a complex adaptation strategy at the neuromuscular level is needed in order to be able to move safely with a prosthetic knee. In literature, it has been demonstrated that muscle activity during walking can be described via the activation of a small set of muscle synergies. The analysis of the composition and the time activation profiles of such synergies have been found to be a valid tool for the description of the motor control schemes in pathological subjects. Methods In this study, we used muscle synergy analysis techniques to characterize the differences in the modular motor control schemes between a population of 14 people with trans-femoral amputation and 12 healthy subjects walking at two different (slow and normal self-selected) speeds. Muscle synergies were extracted from a 12 lower-limb muscles sEMG recording via non-negative matrix factorization. Equivalence of the synergy vectors was quantified by a cross-validation procedure, while differences in terms of time activation coefficients were evaluated through the analysis of the activity in the different gait sub-phases. Results Four synergies were able to reconstruct the muscle activity in all subjects. The spatial component of the synergy vectors did not change in all the analysed populations, while differences were present in the activity during the sound limb’s stance phase. Main features of people with trans-femoral amputation’s muscle synergy recruitment are a prolonged activation of the module composed of calf muscles and an additional activity of the hamstrings’ module before and after the prosthetic heel strike. Conclusions Synergy-based results highlight how, although the complexity and the spatial organization of motor control schemes are the same found in healthy subjects, substantial differences are present in the synergies’ recruitment of people with trans femoral amputation. In particular, the most critical task during the gait cycle is the weight transfer from the sound limb to the prosthetic one. Future studies will integrate these results with the dynamics of movement, aiming to a complete neuro-mechanical characterization of people with trans-femoral amputation’s walking strategies that can be used to improve the rehabilitation therapies.

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