scholarly journals Flexible Recruitments of Fundamental Muscle Synergies in the Trunk and Lower Limbs for Highly Variable Movements and Postures

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6186
Author(s):  
Hiroki Saito ◽  
Hikaru Yokoyama ◽  
Atsushi Sasaki ◽  
Tatsuya Kato ◽  
Kimitaka Nakazawa
Keyword(s):  
Neural Control ◽  
Static Stability ◽  
Neural Representation ◽  
Lower Limbs ◽  
Muscle Synergies ◽  
Functional Roles ◽  
Lower Limb Muscles ◽  
Low Dimensionality ◽  
The Central Nervous System ◽  
Almost All

The extent to which muscle synergies represent the neural control of human behavior remains unknown. Here, we tested whether certain sets of muscle synergies that are fundamentally necessary across behaviors exist. We measured the electromyographic activities of 26 muscles, including bilateral trunk and lower limb muscles, during 24 locomotion, dynamic and static stability tasks, and we extracted the muscle synergies using non-negative matrix factorization. Our results show that 13 muscle synergies that may have unique functional roles accounted for almost all 24 tasks by combinations of single and/or merging of synergies. Therefore, our results may support the notion of the low dimensionality in motor outputs, in which the central nervous system flexibly recruits fundamental muscle synergies to execute diverse human behaviors. Further studies are required to validate the neural representation of the fundamental components of muscle synergies.

scholarly journals Flexible recruitments of fundamental muscle synergies in the trunk and lower limbs for highly variable movements and postures

2021 ◽  
Author(s):  
Hiroki Saito ◽  
Hikaru Yokoyama ◽  
Atsushi Sasaki ◽  
Tatsuya Kato ◽  
Kimitaka Nakazawa
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neural Control ◽  
Static Stability ◽  
Neural Representation ◽  
Lower Limbs ◽  
Muscle Synergies ◽  
Lower Limb Muscles ◽  
The Central Nervous System ◽  
Almost All

The extent to which muscle synergies represent the neural control of human behavior remains unknown. Here, we tested whether certain sets of muscle synergies that are fundamentally necessary across behaviors exist. We measured the electromyographic activities of 26 muscles including bilateral trunk and lower limb muscles during 24 locomotion, dynamic and static stability tasks, and extracted the muscle synergies using non-negative matrix factorization. Our results showed that 13 muscle synergies that may have unique functional roles accounted for almost all 24 tasks by combinations of single and/or merging of synergies. Therefore, our results may support the notion of the low dimensionality in motor outputs, in which the central nervous system flexibly recruits fundamental muscle synergies to execute diverse human behaviors. Further studies using manipulations of the central nervous system and/or neural recording are required the neural representation with such fundamental components of muscle synergies.

Consistency of muscle synergies during pedaling across different mechanical constraints

2011 ◽  
Vol 106 (1) ◽  
pp. 91-103 ◽  
Author(s):  
François Hug ◽  
Nicolas A. Turpin ◽  
Antoine Couturier ◽  
Sylvain Dorel
Keyword(s):  
Neural Control ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Mechanical Constraints ◽  
Relative Contribution ◽  
Lower Limb Muscles ◽  
Emg Patterns ◽  
Mean Variance ◽  
Relative Weighting ◽  
Non Negative Matrix Factorization

The purpose of the present study was to determine whether muscle synergies are constrained by changes in the mechanics of pedaling. The decomposition algorithm used to identify muscle synergies was based on two components: “muscle synergy vectors,” which represent the relative weighting of each muscle within each synergy, and “synergy activation coefficients,” which represent the relative contribution of muscle synergy to the overall muscle activity pattern. We hypothesized that muscle synergy vectors would remain fixed but that synergy activation coefficients could vary, resulting in observed variations in individual electromyographic (EMG) patterns. Eleven cyclists were tested during a submaximal pedaling exercise and five all-out sprints. The effects of torque, maximal torque-velocity combination, and posture were studied. First, muscle synergies were extracted from each pedaling exercise independently using non-negative matrix factorization. Then, to cross-validate the results, muscle synergies were extracted from the entire data pooled across all conditions, and muscle synergy vectors extracted from the submaximal exercise were used to reconstruct EMG patterns of the five all-out sprints. Whatever the mechanical constraints, three muscle synergies accounted for the majority of variability [mean variance accounted for (VAF) = 93.3 ± 1.6%, VAF muscle > 82.5%] in the EMG signals of 11 lower limb muscles. In addition, there was a robust consistency in the muscle synergy vectors. This high similarity in the composition of the three extracted synergies was accompanied by slight adaptations in their activation coefficients in response to extreme changes in torque and posture. Thus, our results support the hypothesis that these muscle synergies reflect a neural control strategy, with only a few timing adjustments in their activation regarding the mechanical constraints.

scholarly journals Modules in the brain stem and spinal cord underlying motor behaviors

2011 ◽  
Vol 106 (3) ◽  
pp. 1363-1378 ◽  
Author(s):  
Jinsook Roh ◽  
Vincent C. K. Cheung ◽  
Emilio Bizzi
Keyword(s):  
Spinal Cord ◽  
Brain Stem ◽  
Muscle Synergies ◽  
Motor Behaviors ◽  
Leg Muscles ◽  
Before And After ◽  
The Central Nervous System ◽  
Almost All ◽  
Open Question ◽  
The Brain

Previous studies using intact and spinalized animals have suggested that coordinated movements can be generated by appropriate combinations of muscle synergies controlled by the central nervous system (CNS). However, which CNS regions are responsible for expressing muscle synergies remains an open question. We address whether the brain stem and spinal cord are involved in expressing muscle synergies used for executing a range of natural movements. We analyzed the electromyographic (EMG) data recorded from frog leg muscles before and after transection at different levels of the neuraxis—rostral midbrain (brain stem preparations), rostral medulla (medullary preparations), and the spinal-medullary junction (spinal preparations). Brain stem frogs could jump, swim, kick, and step, while medullary frogs could perform only a partial repertoire of movements. In spinal frogs, cutaneous reflexes could be elicited. Systematic EMG analysis found two different synergy types: 1) synergies shared between pre- and posttransection states and 2) synergies specific to individual states. Almost all synergies found in natural movements persisted after transection at rostral midbrain or medulla but not at the spinal-medullary junction for swim and step. Some pretransection- and posttransection-specific synergies for a certain behavior appeared as shared synergies for other motor behaviors of the same animal. These results suggest that the medulla and spinal cord are sufficient for the expression of most muscle synergies in frog behaviors. Overall, this study provides further evidence supporting the idea that motor behaviors may be constructed by muscle synergies organized within the brain stem and spinal cord and activated by descending commands from supraspinal areas.

MUSCULOSKELETAL TRAINING AND MECHANICAL CHARACTERISTICS OF ATHLETES

2021 ◽  
Vol 27 (7) ◽  
pp. 750-752
Author(s):  
Bo Han ◽  
Baosen Wang
Keyword(s):  
Lower Limb ◽  
Mechanical Characteristics ◽  
Exercise Physiology ◽  
Deformation Energy ◽  
Point Of View ◽  
Lower Limbs ◽  
Level Of Evidence ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
The Central Nervous System

ABSTRACT Introduction: Studying the biomechanical characteristics of lower limb muscles during depth jumps is of great significance, but it is also important in meeting the practical needs of strength training. Objective: To explore the musculoskeletal exercise training and mechanical characteristics of athletes’ lower limbs. Methods: Analysis and discussion of the test results of kinematics, dynamics and the EMG of 8 muscles of the lower extremity when athletes jump at different falling heights and different motion states. Results: only by using different falling heights in a certain proportion can training efficiency be improved and the training effect of depth jumps reach the practical purpose of sports training. Conclusions: from the point of view of exercise physiology, the generation, storage and reuse of muscle elastic deformation energy and the reflex regulation of the central nervous system are the main reasons for the economic and efficient contractive ability of the extensor muscle group of lower limbs during depth jumps. From the point of view of muscle mechanical properties, the centrifugal contractility of lower limb muscles is the primary factor that determines the athletes’ lower limb muscle explosive push ability. Level of evidence II; Therapeutic studies - investigation of treatment results.

scholarly journals Unilateral and Bilateral Strength Asymmetry among Young Elite Athletes of Various Sports

Medicina ◽  
2020 ◽  
Vol 56 (12) ◽  
pp. 683
Author(s):  
Maros Kalata ◽  
Tomas Maly ◽  
Mikulas Hank ◽  
Jakub Michalek ◽  
David Bujnovsky ◽  
...  
Keyword(s):  
Lower Limb ◽  
Elite Athletes ◽  
Lower Limbs ◽  
Knee Extensors ◽  
Young Athletes ◽  
Lower Limb Muscles ◽  
Significant Difference ◽  
Strength Asymmetry ◽  
Main Factor ◽  
Objective Type

Background and objective: Type of physical activity may influence morphological and muscular asymmetries in the young population. However, less is known about the size of this effect when comparing various sports. The aim of this study was to identify the degree of bilateral asymmetry (BA) and the level of unilateral ratio (UR) between isokinetic strength of knee extensors (KE) and flexors (KF) among athletes of three different types of predominant locomotion in various sports (symmetric, asymmetric and hybrid). Material and methods: The analyzed group consisted of young elite athletes (n = 50). The maximum peak muscle torque of the KE and KF in both the dominant (DL) and non-dominant (NL) lower limb during concentric muscle contraction at an angular velocity of 60°·s−1 was measured with an isokinetic dynamometer. Results: Data analysis showed a significant effect of the main factor (the type of sport) on the level of monitored variables (p = 0.004). The type of sport revealed a significant difference in the bilateral ratio (p = 0.01). The group of symmetric and hybrid sports achieved lower values (p = 0.01) of BA in their lower limb muscles than those who played asymmetric sports. The hybrid sports group achieved higher UR values (p = 0.01) in both lower limbs. Conclusions: The results indicate that sports with predominantly symmetrical, asymmetrical, and hybrid types of locomotion affected the size of the BA, as well as the UR between KE and KF in both legs in young athletes. We recommend paying attention to regular KE and KF strength diagnostics in young athletes and optimizing individual compensatory exercises if a higher ratio of strength asymmetry is discovered.

Muscle Function and Coordination of Stair Ascent

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Nicole G. Harper ◽  
Jason M. Wilken ◽  
Richard R. Neptune
Keyword(s):  
Three Dimensional ◽  
Gluteus Maximus ◽  
Gluteus Medius ◽  
Patient Specific ◽  
Functional Roles ◽  
Stair Ascent ◽  
Lower Limb Muscles ◽  
Ankle Joints ◽  
Community Environments ◽  
Antagonistic Muscles

Stair ascent is an activity of daily living and necessary for maintaining independence in community environments. One challenge to improving an individual's ability to ascend stairs is a limited understanding of how lower-limb muscles work in synergy to perform stair ascent. Through dynamic coupling, muscles can perform multiple functions and require contributions from other muscles to perform a task successfully. The purpose of this study was to identify the functional roles of individual muscles during stair ascent and the mechanisms by which muscles work together to perform specific subtasks. A three-dimensional (3D) muscle-actuated simulation of stair ascent was generated to identify individual muscle contributions to the biomechanical subtasks of vertical propulsion, anteroposterior (AP) braking and propulsion, mediolateral control and leg swing. The vasti and plantarflexors were the primary contributors to vertical propulsion during the first and second halves of stance, respectively, while gluteus maximus and hamstrings were the primary contributors to forward propulsion during the first and second halves of stance, respectively. The anterior and posterior components of gluteus medius were the primary contributors to medial control, while vasti and hamstrings were the primary contributors to lateral control during the first and second halves of stance, respectively. To control leg swing, antagonistic muscles spanning the hip, knee, and ankle joints distributed power from the leg to the remaining body segments. These results compliment previous studies analyzing stair ascent and provide further rationale for developing targeted rehabilitation strategies to address patient-specific deficits in stair ascent.

Deficits in anticipatory inhibition of postural muscle activity associated with load release while standing in individuals with spastic diplegic cerebral palsy

2013 ◽  
Vol 109 (8) ◽  
pp. 1996-2006 ◽  
Author(s):  
Hidehito Tomita ◽  
Yoshiki Fukaya ◽  
Kenji Totsuka ◽  
Yuri Tsukahara
Keyword(s):  
Cerebral Palsy ◽  
Lower Limb ◽  
Muscle Activity ◽  
Erector Spinae ◽  
Lower Limbs ◽  
Control Group ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Postural Muscle ◽  
Load Release

This study aimed to determine whether individuals with spastic diplegic cerebral palsy (SDCP) have deficits in anticipatory inhibition of postural muscle activity. Nine individuals with SDCP (SDCP group, 3 female and 6 male, 13–24 yr of age) and nine age- and sex-matched individuals without disability (control group) participated in this study. Participants stood on a force platform, which was used to measure the position of the center of pressure (CoP), while holding a light or heavy load in front of their bodies. They then released the load by abducting both shoulders. Surface electromyograms were recorded from the rectus abdominis, erector spinae (ES), rectus femoris (RF), medial hamstring (MH), tibialis anterior (TA), and gastrocnemius (GcM) muscles. In the control group, anticipatory inhibition before load release and load-related modulation of the inhibition were observed in all the dorsal muscles recorded (ES, MH, and GcM). In the SDCP group, similar results were obtained in the trunk muscle (ES) but not in the lower limb muscles (MH and GcM), although individual differences were seen, especially in MH. Anticipatory activation of the ventral lower limb muscles (RF and TA) and load-related modulation of the activation were observed in both participant groups. CoP path length during load release was longer in the SDCP group than in the control group. The present findings suggest that individuals with SDCP exhibit deficits in anticipatory inhibition of postural muscles at the dorsal part of the lower limbs, which is likely to result in a larger disturbance of postural equilibrium.

scholarly journals Neural Prosthetics:A Review of Empirical vs. Systems Engineering Strategies

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Gerald E. Loeb
Keyword(s):  
Nervous System ◽  
Systems Engineering ◽  
Neural Control ◽  
Cardiac Pacemaker ◽  
Clinical Problem ◽  
Neural Prosthetic ◽  
The Many ◽  
Almost All ◽  
Electronic Technologies ◽  
Interface Materials

Implantable electrical interfaces with the nervous system were first enabled by cardiac pacemaker technology over 50 years ago and have since diverged into almost all of the physiological functions controlled by the nervous system. There have been a few major clinical and commercial successes, many contentious claims, and some outright failures. These tend to be reviewed within each clinical subspecialty, obscuring the many commonalities of neural control, biophysics, interface materials, electronic technologies, and medical device regulation that they share. This review cites a selection of foundational and recent journal articles and reviews for all major applications of neural prosthetic interfaces in clinical use, trials, or development. The hard-won knowledge and experience across all of these fields can now be amalgamated and distilled into more systematic processes for development of clinical products instead of the often empirical (trial and error) approaches to date. These include a frank assessment of a specific clinical problem, the state of its underlying science, the identification of feasible targets, the availability of suitable technologies, and the path to regulatory and reimbursement approval. Increasing commercial interest and investment facilitates this systematic approach, but it also motivates projects and products whose claims are dubious.

scholarly journals Ocular Autonomic Nervous System: An Update from Anatomy to Physiological Functions

Vision ◽  
2022 ◽  
Vol 6 (1) ◽  
pp. 6
Author(s):  
Feipeng Wu ◽  
Yin Zhao ◽  
Hong Zhang
Keyword(s):  
Nervous System ◽  
Autonomic Nervous System ◽  
Neural Control ◽  
Entire Body ◽  
Physiological Functions ◽  
Autonomic Nervous ◽  
Parasympathetic Nerves ◽  
Physiological Processes ◽  
New Research ◽  
Almost All

The autonomic nervous system (ANS) confers neural control of the entire body, mainly through the sympathetic and parasympathetic nerves. Several studies have observed that the physiological functions of the eye (pupil size, lens accommodation, ocular circulation, and intraocular pressure regulation) are precisely regulated by the ANS. Almost all parts of the eye have autonomic innervation for the regulation of local homeostasis through synergy and antagonism. With the advent of new research methods, novel anatomical characteristics and numerous physiological processes have been elucidated. Herein, we summarize the anatomical and physiological functions of the ANS in the eye within the context of its intrinsic connections. This review provides novel insights into ocular studies.

scholarly journals Gaseous neurotransmitter nitric oxide: Its role in experimental models of epilepsy

2012 ◽  
Vol 64 (3) ◽  
pp. 1207-1216 ◽  
Author(s):  
D. Hrncic ◽  
Aleksandra Rasic-Markovic ◽  
Jelica Bjekic-Macut ◽  
Veselinka Susic ◽  
D. Mladenovic ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Experimental Studies ◽  
Experimental Models ◽  
Initiation And Propagation ◽  
Organ Systems ◽  
The Central Nervous System ◽  
Animal Models Of Epilepsy ◽  
Almost All ◽  
Gaseous Neurotransmitter ◽  
Models Of Epilepsy

Epilepsy is one of the leading neurological disorders and affects 1-2% of the world?s population. Generally, it is a result of an imbalance between excitatory and inhibitory phenomena in the central nervous system (CNS), but the mechanisms of its initiation and propagation still require further investigations. Experimental models represent one of the most powerful tools to better understand the mechanisms of epileptogenesis. Nitric oxide (NO) is gaseous molecule with pleiotropic physiological and pathological effects in almost all organ systems and intriguing biological relevance, especially in the CNS where it acts as a gaseous neurotransmitter. The role of NO in the generation of epilepsy is highly contradictory, since there is evidence of its anticonvulsive, as well as proconvulsive properties. Therefore, we will discuss in this review the involvement of NO-mediated signaling pathways in the mechanisms of epileptogenesis, taking into account the findings revealed in experimental studies on animal models of epilepsy.

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