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Muscle synergies

Benjamin R Shuman, Marije Goudriaan, Kaat Desloovere, Michael H Schwartz, Katherine M Steele
OBJECTIVE: To determine whether patient-specific differences in motor control quantified using muscle synergy analysis were associated with changes in gait after treatment in cerebral palsy across two clinical centers with different treatments and clinical protocols. DESIGN: Retrospective Cohort Study. SETTING: Clinical Medical Center. PARTICIPANTS: Center 1: 473 children with cerebral palsy and 84 typically-developing children...
April 9, 2018: Archives of Physical Medicine and Rehabilitation
Luigino Calzetta, Maria Gabriella Matera, Mario Cazzola
Long-acting β2 adrenoceptor agonists (LABAs) in combination with long-acting muscarinic antagonists (LAMAs) can elicit functional and clinical benefits in chronic obstructive pulmonary disease (COPD). LABA/LAMA combinations synergistically relax human isolated airways at the level of the medium and small bronchi. LABAs and LAMAs both modulate the bronchial tone via different pathways localized at the level of presynaptic parasympathetic fibers and airway smooth muscle cells. The exact nature of the interactions between these pathways is not completely understood, but there is cross-talk at many levels in airway smooth muscle cells that is also regulated by the activity of calcium-activated potassium channels and protein tyrosine kinases...
April 4, 2018: Current Opinion in Pharmacology
Kyuengbo Min, Duk Shin, Jongho Lee, Shinji Kakei
Electromyogram signal (EMG) measurement frequently experiences uncertainty attributed to issues caused by technical constraints such as cross talk and maximum voluntary contraction. Due to these problems, individual EMGs exhibit uncertainty in representing their corresponding muscle activations. To regulate this uncertainty, we proposed an EMG refinement, which refines EMGs with regulating the contribution redundancy of the signals from EMGs to approximating torques through EMG-driven torque estimation (EDTE) using the muscular skeletal forward dynamic model...
March 17, 2018: Journal of Biomechanics
Kun Liu, Yong Liu, Jianchao Yan, Zhenyuan Sun
Partial body weight support or loading sit-to-stand (STS) rehabilitation can be useful for persons with lower limb dysfunction to achieve movement again based on the internal residual muscle force and external assistance. To explicate how the muscles contribute to the kinetics and kinematics of STS performance by non-invasive in vitro detection and to nondestructively estimate the muscle contributions to STS training with different loadings, a wearable sensor system was developed with ground reaction force (GRF) platforms, motion capture inertial sensors and electromyography (EMG) sensors...
March 25, 2018: Sensors
Ali Falaki, Hang Jin Jo, Mechelle M Lewis, Barbara O'Connell, Sol De Jesus, James McInerney, Xuemei Huang, Mark L Latash
OBJECTIVE: We explored effects of deep brain stimulation (DBS) in patients with Parkinson's disease (PD) on the synergic control of fingers in a multi-finger force production task and of muscles in a task involving vertical posture. METHODS: The finger task involved the four fingers of a hand producing accurate total force followed by a targeted quick force pulse. The postural task involved releasing a load from extended arms. The analysis of synergies was performed within the framework of the uncontrolled manifold hypothesis...
March 9, 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Momoko Yamagata, Ali Falaki, Mark L Latash
We explored the relations between indices of mechanical stability of vertical posture and synergy indices under unexpected perturbations. The main hypotheses predicted higher posture-stabilizing synergy indices and higher mechanical indices of center of pressure stability during perturbations perceived by subjects as less challenging. Healthy subjects stood on a force platform and held in fully extended arms a bar attached to two loads acting downward and upward. One of the loads was unexpectedly released by the experimenter causing a postural perturbations...
March 21, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Cristian Cuadra, Angelo Bartsch, Paula Tiemann, Sasha Reschechtko, Mark L Latash
We explored whether the synergic control of the hand during multi-finger force production tasks depends on the hand muscles involved. Healthy subjects performed accurate force production tasks and targeted force pulses while pressing against loops positioned at the level of fingertips, middle phalanges, and proximal phalanges. This varied the involvement of the extrinsic and intrinsic finger flexors. The framework of the uncontrolled manifold (UCM) hypothesis was used to analyze the structure of inter-trial variance, motor equivalence, and anticipatory synergy adjustments prior to the force pulse in the spaces of finger forces and finger modes (hypothetical finger-specific control signals)...
March 12, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Sharon Israely, Gerry Leisman, Chay C Machluf, Eli Carmeli
Purpose: A muscle synergies model was suggested to represent a simplifying motor control mechanism by the brainstem and spinal cord. The aim of the study was to investigate the feasibility of such control mechanisms in the rehabilitation of post-stroke individuals during the execution of hand-reaching movements in multiple directions, compared to non-stroke individuals. Methods: Twelve non-stroke and 13 post-stroke individuals participated in the study. Muscle synergies were extracted from EMG data that was recorded during hand reaching tasks, using the NMF algorithm...
2018: Frontiers in Computational Neuroscience
J Iskander, M Hossny, S Nahavandi, L Del Porto
Simulating and analysing eye movement is useful for assessing visual system contribution to discomfort with respect to body movements, especially in virtual environments where simulation sickness might occur. It can also be used in the design of eye prosthesis or humanoid robot eye. In this paper, we present two biomechanic ocular models that are easily integrated into the available musculoskeletal models. The model was previously used to simulate eye-head coordination. The models are used to simulate and analyse eye movements...
February 16, 2018: Journal of Biomechanics
Qing Ji, Fei Wang, Rui Zhou, Jianhua Li, Jian Wang, Xuesong Ye
Impaired ankle dorsal and plantar flexor function is a frequent sequela of stroke. A better assessment of ankle muscle activation would be highly significant for stroke rehabilitation. The challenge in implementing current electromyography (EMG)-based assessments is due to problems with the variability and individuality of ankle muscle EMG profiles during walking. We have been studying a new technique using the muscle synergy method to quantify the characteristics that underlie ankle muscle activation to address this issue...
February 28, 2018: Physiological Measurement
Jacob G McPherson, Albert Chen, Michael D Ellis, Jun Yao, C J Heckman, Julius P A Dewald
KEY POINTS: Activation of the shoulder abductor muscles in the arm opposite a unilateral brain injury causes involuntary increases in elbow, wrist and finger flexion in the same arm, a phenomenon referred to as the flexion synergy. It has been proposed that flexion synergy expression is related to reduced output from ipsilesional motor cortex and corticospinal pathways. In this human subjects study, we provide evidence that the magnitude of flexion synergy expression is instead related to a progressive, task-dependent recruitment of contralesional cortex...
February 19, 2018: Journal of Physiology
Marije Goudriaan, Benjamin R Shuman, Katherine M Steele, Marleen Van den Hauwe, Nathalie Goemans, Guy Molenaers, Kaat Desloovere
Cerebral palsy (CP) and Duchenne muscular dystrophy (DMD) are neuromuscular disorders characterized by muscle weakness. Weakness in CP has neural and non-neural components, whereas in DMD, weakness can be considered as a predominantly non-neural problem. Despite the different underlying causes, weakness is a constraint for the central nervous system when controlling gait. CP demonstrates decreased complexity of motor control during gait from muscle synergy analysis, which is reflected by a higher total variance accounted for by one synergy (tVAF1 )...
2018: Frontiers in Human Neuroscience
Alessandro Santuz, Antonis Ekizos, Nils Eckardt, Armin Kibele, Adamantios Arampatzis
The need to move over uneven terrain is a daily challenge. In order to face unexpected perturbations due to changes in the morphology of the terrain, the central nervous system must flexibly modify its control strategies. We analysed the local dynamic stability and the modular organisation of muscle activation (muscle synergies) during walking and running on an even- and an uneven-surface treadmill. We hypothesized a reduced stability during uneven-surface locomotion and a reorganisation of the modular control...
February 9, 2018: Scientific Reports
Benio Kibushi, Shota Hagio, Toshio Moritani, Motoki Kouzaki
The regulation of walking speed is easily achieved. However, the central nervous system (CNS) must coordinate numerous muscles in order to achieve a smooth and continuous control of walking speed. To control walking speed appropriately, the CNS may need to utilize a simplified system for the control of numerous muscles. Previous studies have revealed that the CNS may control walking via muscle synergies that simplify the control of muscles by modularly organizing several muscles. We hypothesized that the CNS controls the walking speed by flexibly modulating activation of muscle synergies within one gait cycle...
2018: Frontiers in Human Neuroscience
Clare C Maguire, Judith M Sieben, Robert A De Bie
Current knowledge of neural and neuromuscular processes controlling gait and movement as well as an understanding of how these mechanisms change following stroke is an important basis for the development of effective rehabilitation interventions. To support the translation of findings from basic research into useful treatments in clinical practice, up-to-date neuroscience should be presented in forms accessible to all members of the multidisciplinary team. In this review we discuss aspects of cortical control of gait and movement, muscle synergies as a way of translating cortical commands into specific muscle activity and as an efficient means of reducing neural and musculoskeletal redundancy...
February 5, 2018: Physiotherapy Theory and Practice
Sharon Israely, Gerry Leisman, Eli Carmeli
Muscle synergies are proposed to function as motor primitives that are modulated by frontal brain areas to construct a large repertoire of movement. This paper reviews the history of the development of our current theoretical understanding of nervous system-based motor control mechanisms and more specifically the concept of muscle synergies. Computational models of muscle synergies, especially the nonnegative matrix factorization algorithm, are discussed with specific reference to the changes in synergy control post-central nervous system (CNS) lesions...
February 5, 2018: Reviews in the Neurosciences
Laura Pellegrino, Martina Coscia, Margit Muller, Claudio Solaro, Maura Casadio
Multiple sclerosis is a chronic, autoimmune and neurodegenerative disease affecting multiple functional systems and resulting in motor impairments associated with muscle weakness and lack of movement coordination. We quantified upper limb motor deficits with a robot-based assessment including behavioral and muscle synergy analysis in 11 multiple sclerosis subjects with mild to moderate upper limb impairment (9 female; 50 ± 10 years) compared to 11 age- and gender- matched controls (9 female; 50 ± 9 years)...
February 1, 2018: Scientific Reports
Kyuengbo Min, Masami Iwamoto, Shinji Kakei, Hideyuki Kimpara
Humans are able to robustly maintain desired motion and posture under dynamically changing circumstances, including novel conditions. To accomplish this, the brain needs to optimize the synergistic control between muscles against external dynamic factors. However, previous related studies have usually simplified the control of multiple muscles using two opposing muscles, which are minimum actuators to simulate linear feedback control. As a result, they have been unable to analyze how muscle synergy contributes to motion control robustness in a biological system...
January 30, 2018: Neural Computation
Sandra Rutting, Dia Xenaki, Edmund Lau, Jay C Horvat, Lisa G Wood, Philip M Hansbro, Brian G Oliver
Obesity is an important risk factor for developing severe asthma. Dietary fatty acids which are increased in sera of obese individuals and after high fat meals, activate the innate immune system and induce inflammation. This study investigated whether dietary fatty acids directly cause inflammation and/or synergise with obesity-induced cytokines in primary human pulmonary fibroblasts in vitro. Fibroblasts were challenged with BSA-conjugated fatty acids (ω-6 PUFAs, ω-3 PUFAs or SFAs) with or without TNFα and release of the pro-inflammatory cytokines, IL-6 and CXCL8, was measured...
January 25, 2018: American Journal of Physiology. Lung Cellular and Molecular Physiology
Luigi Iuppariello, Giovanni D'Addio, Maria Romano, Paolo Bifulco, Nicola Pappone, Bernardo Lanzillo, Mario Cesarelli
BACKGROUND: The recovery of the functional limb mobility of patients with cerebral damages can take great benefit of the role offered by proprioceptive rehabilitation. Recently have been developed a special Regent Suit (RS) for rehabilitative applications. Actually, there are preliminary studies which describes the effects of RS on gait recovery of stroke patients in acute stage, but none in chronic stage. Moreover, it is known that motor recovery does not always reflect improvements of the muscle activity and coactivity...
January 11, 2018: European Journal of Physical and Rehabilitation Medicine
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