scholarly journals Number of Trials Necessary to Apply Analysis within the Framework of the Uncontrolled Manifold Hypothesis at Different Levels of Hierarchical Synergy Control

2021 ◽  
Vol 76 (1) ◽  
pp. 131-143
Author(s):  
Michał Pawłowski ◽  
Mariusz P. Furmanek ◽  
Grzegorz Sobota ◽  
Wojciech Marszałek ◽  
Kajetan J. Słomka ◽  
...  
Keyword(s):  
Intraclass Correlation ◽  
Hierarchical Control ◽  
Large Body ◽  
Elbow Flexion ◽  
Uncontrolled Manifold ◽  
Uncontrolled Manifold Hypothesis ◽  
Motor Synergies ◽  
Minimum Number ◽  
Motor Actions ◽  
Different Levels

Abstract The uncontrolled manifold hypothesis is a method used to quantify motor synergies, defined as a specific central nervous system organization that maintains the task-specific stability of motor actions. The UCM allows for inter-trial variance analysis between consecutive trials. However, despite the large body of literature within this framework, there is no report on the number of movement repetitions required for reliable results. Based on the hypothetical hierarchical control of motor synergies, this study aims to determine the minimum number of trials necessary to achieve a good to excellent level of reliability. Thirteen young, healthy participants performed fifteen bilateral isometric contractions of elbow flexion when visual feedback was provided. The force and electromyography data were recorded to investigate synergies at different levels of hierarchical control. The intraclass correlation coefficient was used to determine the reliability of the variance indices. Based on the obtained results, at least twelve trials are required to analyze the inter-trial variance in both force and muscle synergies within the UCM framework.

Performance-Stabilizing Synergies in a Complex Motor Skill: Analysis Based on the Uncontrolled Manifold Hypothesis

Motor Control ◽  
2020 ◽  
Vol 24 (2) ◽  
pp. 238-252
Author(s):  
Fariba Hasanbarani ◽  
Mark L. Latash
Keyword(s):  
Hierarchical Control ◽  
Uncontrolled Manifold ◽  
Time Varying ◽  
Uncontrolled Manifold Hypothesis ◽  
Small Ball ◽  
Complex Motor ◽  
Eyes Open ◽  
Skill Analysis ◽  
Joint Velocity ◽  
Different Levels

The authors studied indices of stability (ΔV) of two time-varying variables, hand coordinate and velocity, during accurate throw of a small ball into the basket. Ten participants performed the throwing task with eyes-open (vision) and -closed (no vision) conditions. In the latter condition, participants closed their eyes prior to initiating the throw. The intertrial variance in the joint configuration space (and joint velocity space) was analyzed based on the uncontrolled manifold hypothesis. The results confirmed the presence of both coordinate- and velocity-stabilizing synergies (ΔV > 0). Intertrial variance was larger in the no-vision condition compared with the vision condition. Over the movement duration, ΔV did not change for the coordinate-related analysis but dropped consistently for the velocity-related analysis. The authors interpret the findings within the idea of hierarchical control and trade-off between synergy indices at different levels of the hierarchy.

scholarly journals The Hand: Shall We Ever Understand How It Works?

Motor Control ◽  
2015 ◽  
Vol 19 (2) ◽  
pp. 108-126 ◽  
Author(s):  
Mark L. Latash
Keyword(s):  
Motor Control ◽  
Equilibrium Point ◽  
Neurological Disorder ◽  
Neural Control ◽  
Hierarchical Control ◽  
Uncontrolled Manifold ◽  
Human Hand ◽  
Uncontrolled Manifold Hypothesis ◽  
Target Article ◽  
Point Control

The target article presents a review of the neural control of the human hand. The review emphasizes the physical approach to motor control. It focuses on such concepts as equilibrium-point control, control with referent body configurations, uncontrolled manifold hypothesis, principle of abundance, hierarchical control, multidigit synergies, and anticipatory synergy adjustments. Changes in aspects of the hand neural control with age and neurological disorder are discussed. The target article is followed by six commentaries written by Alexander Aruin, Kelly Cole, Monica Perez, Robert Sainburg, Marco Sanello, and Wei Zhang.

Abundant Degrees of Freedom Are Not a Problem

2018 ◽  
Vol 7 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Mark L. Latash
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Methods ◽  
Uncontrolled Manifold ◽  
Motor Tasks ◽  
Uncontrolled Manifold Hypothesis ◽  
Motor Synergies ◽  
External Forces ◽  
Applied Fields ◽  
The Brain ◽  
Additional Constraints

The problem of motor redundancy has been one of the fundamental, albeit elusive, problems in motor control. Traditionally, it has been viewed as a computational problem for the brain, solved with either optimization methods or by introducing additional constraints to motor tasks. This review suggests that the problem was wrongly formulated, and that the abundant degrees of freedom are not to be eliminated but used to ensure dynamic stability of motor performance, which is vital given the unpredictable intrinsic states and external forces. The idea of synergies as mechanisms ensuring action stability is introduced based on the uncontrolled manifold hypothesis and the theory of control with spatial referent coordinates. The importance of controlled stability is illustrated with the phenomena of anticipatory synergy adjustments. This approach is productive for both basic and applied fields as illustrated, in particular, by changes in motor synergies with neurological disorder and exercise.

scholarly journals Scarcity of scale-free topology is universal across biochemical networks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Harrison B. Smith ◽  
Hyunju Kim ◽  
Sara I. Walker
Keyword(s):  
Large Body ◽  
Biochemical Networks ◽  
Biological Organization ◽  
Scale Free ◽  
Levels Of Organization ◽  
Common Structure ◽  
Domains Of Life ◽  
Ecosystem Level ◽  
Different Levels ◽  
Organizing Principles

AbstractBiochemical reactions underlie the functioning of all life. Like many examples of biology or technology, the complex set of interactions among molecules within cells and ecosystems poses a challenge for quantification within simple mathematical objects. A large body of research has indicated many real-world biological and technological systems, including biochemistry, can be described by power-law relationships between the numbers of nodes and edges, often described as “scale-free”. Recently, new statistical analyses have revealed true scale-free networks are rare. We provide a first application of these methods to data sampled from across two distinct levels of biological organization: individuals and ecosystems. We analyze a large ensemble of biochemical networks including networks generated from data of 785 metagenomes and 1082 genomes (sampled from the three domains of life). The results confirm no more than a few biochemical networks are any more than super-weakly scale-free. Additionally, we test the distinguishability of individual and ecosystem-level biochemical networks and show there is no sharp transition in the structure of biochemical networks across these levels of organization moving from individuals to ecosystems. This result holds across different network projections. Our results indicate that while biochemical networks are not scale-free, they nonetheless exhibit common structure across different levels of organization, independent of the projection chosen, suggestive of shared organizing principles across all biochemical networks.

New Models for Motor Control

1989 ◽  
Vol 1 (2) ◽  
pp. 173-183 ◽  
Author(s):  
Jennifer S. Altman ◽  
Jenny Kien
Keyword(s):  
Distributed Control ◽  
Hierarchical Control ◽  
Sensory Information ◽  
Striking Similarity ◽  
Maximum Efficiency ◽  
Behavioral Choice ◽  
Modular Control ◽  
Superficial Resemblance ◽  
Different Levels ◽  
Command Center

What do a prototype robot (Brooks 1989) and a model for the control of behavioral choice in insects (Altman and Kien 1987a) have in common? And what do they share with a scratching cat (Shadmehr 1989)? The answer is distributed control systems that do not depend on a central command center for the execution of behavioral outputs. The first two in particular are examples of a growing trend to replace the long-held concept of linear hierarchical control of motor output with one of decentralized, distributed control, with inputs at many levels and the output a consensus of the activity in several centers. Brooks (1989) describes a six-legged machine that, in its most advanced form, can walk over rough terrain and prowl around following a source of warmth, such as a person. The six legs, chosen as a compromise between stability and ease of coordination, give the robot a superficial resemblance to an insect — but the similarity goes deeper. The modular control system, designed strictly on engineering principles for maximum efficiency and economy, bears a striking similarity to the model we have proposed elsewhere (Altman and Kien 1987a) to describe the organization of the motor system in insects such as the locust. In both systems, the same set of components can generate different behaviors, depending on the context, and similar principles govern the generation of different levels of behavior, from movements of a single leg to coordinated responses of the whole beast. Neither requires a single center for integrating all sensory information and conflicts tend to be resolved by consensus at the motor level.

scholarly journals Synergies in coordination: a comprehensive overview of neural, computational, and behavioral approaches

2018 ◽  
Vol 120 (6) ◽  
pp. 2761-2774 ◽  
Author(s):  
Michaela Bruton ◽  
Nicholas O’Dwyer
Keyword(s):  
Motor Control ◽  
Hierarchical Control ◽  
Research Approach ◽  
Comprehensive Overview ◽  
Control Scheme ◽  
The One ◽  
Explanatory Concept ◽  
Different Levels ◽  
And Task

At face value, the term “synergy” provides a unifying concept within a fractured field that encompasses complementary neural, computational, and behavioral approaches. However, the term is not used synonymously by different researchers but has substantially different meanings depending on the research approach. With so many operational definitions for the one term, it becomes difficult to use as either a descriptive or explanatory concept, yet it remains pervasive and apparently indispensable. Here we provide a summary of different approaches that invoke synergies in a descriptive or explanatory context, summarizing progress, not within the one approach, but across the theoretical landscape. Bernstein’s framework of flexible hierarchical control may provide a unifying framework here, since it can incorporate divergent ideas about synergies. In the current motor control literature, synergy may refer to conceptually different processes that could potentially operate in parallel, across different levels within the same hierarchical control scheme. There is evidence for the concurrent existence of synergies with different features, both “hard-wired” and “soft-wired,” and task independent and task dependent. By providing a comprehensive overview of the multifaceted ideas about synergies, our goal is to move away from the compartmentalization and narrow the focus on one level and promote a broader perspective on the control and coordination of movement.

Crossmodal Association Between Linguistic Sounds and Motion Imagery: Voicing in Obstruents Connects With Different Strengths of Motor Execution

Perception ◽  
2019 ◽  
Vol 48 (6) ◽  
pp. 530-540 ◽  
Author(s):  
Naoto Yamauchi ◽  
Kazuko Shinohara ◽  
Hideyuki Tanaka
Keyword(s):  
Auditory Perception ◽  
Implicit Association Test ◽  
Implicit Association ◽  
Motor Execution ◽  
Experimental Support ◽  
Motion Imagery ◽  
Static Pictures ◽  
Crossmodal Associations ◽  
Motor Actions ◽  
Different Levels

The present study investigates whether obstruent voicing may or may not affect the imagery of different strengths of motor execution. In a modified version of the implicit association test, participants responded to discrimination tasks that include viewing static pictures of athletes in motion and hearing mono-syllabic linguistic sounds. The results suggest that voiced obstruents are compatible with the motion imagery that implies stronger motor executions, whereas voiceless obstruents are compatible with the imagery that implies weaker motor executions. These results provide experimental support for crossmodal associations between the auditory perception of linguistic sounds, namely, the voicing of obstruents, and the visually induced imagery of different levels of strength in motor actions.

scholarly journals Optimizing design to estimate genetic correlations between environments with common environmental effects

2020 ◽  
Vol 98 (2) ◽  
Author(s):  
Maria Lozano-Jaramillo ◽  
Hans Komen ◽  
Yvonne C J Wientjes ◽  
Han A Mulder ◽  
John W M Bastiaansen
Keyword(s):  
Genetic Correlation ◽  
Environmental Effects ◽  
Genetic Correlations ◽  
Improve Performance ◽  
Breeding Programs ◽  
Genotype By Environment ◽  
Optimizing Design ◽  
Minimum Number ◽  
Optimal Population ◽  
Different Levels

Abstract Breeding programs for different species aim to improve performance by testing members of full-sib (FS) and half-sib (HS) families in different environments. When genotypes respond differently to changes in the environment, this is defined as genotype by environment (G × E) interaction. The presence of common environmental effects within families generates covariance between siblings, and these effects should be taken into account when estimating a genetic correlation. Therefore, an optimal design should be established to accurately estimate the genetic correlation between environments in the presence of common environmental effects. We used stochastic simulation to find the optimal population structure using a combination of FS and HS groups with different levels of common environmental effects. Results show that in a population with a constant population size of 2,000 individuals per environment, ignoring common environmental effects when they are present in the population will lead to an upward bias in the estimated genetic correlation of on average 0.3 when the true genetic correlation is 0.5. When no common environmental effects are present in the population, the lowest standard error (SE) of the estimated genetic correlation was observed with a mating ratio of one dam per sire, and 10 offspring per sire per environment. When common environmental effects are present in the population and are included in the model, the lowest SE is obtained with mating ratios of at least 5 dams per sire and with a minimum number of 10 offspring per sire per environment. We recommend that studies that aim to estimate the magnitude of G × E in pigs, chicken, and fish should acknowledge the potential presence of common environmental effects and adjust the mating ratio accordingly.

scholarly journals Standardising the measurement of physical activity in people receiving haemodialysis: considerations for research and practice

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Hannah M. L. Young ◽  
Mark W. Orme ◽  
Yan Song ◽  
Maurice Dungey ◽  
James O. Burton ◽  
...  
Keyword(s):  
Physical Activity ◽  
Sample Size ◽  
Repeated Measures ◽  
A Priori ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Future Research ◽  
Wear Time ◽  
Minimum Number ◽  
The Uk

Abstract Background Physical activity (PA) is exceptionally low amongst the haemodialysis (HD) population, and physical inactivity is a powerful predictor of mortality, making it a prime focus for intervention. Objective measurement of PA using accelerometers is increasing, but standard reporting guidelines essential to effectively evaluate, compare and synthesise the effects of PA interventions are lacking. This study aims to (i) determine the measurement and processing guidance required to ensure representative PA data amongst a diverse HD population, and; (ii) to assess adherence to PA monitor wear amongst HD patients. Methods Clinically stable HD patients from the UK and China wore a SenseWear Armband accelerometer for 7 days. Step count between days (HD, Weekday, Weekend) were compared using repeated measures ANCOVA. Intraclass correlation coefficients (ICCs) determined reliability (≥0.80 acceptable). Spearman-Brown prophecy formula, in conjunction with a priori ≥  80% sample size retention, identified the minimum number of days required for representative PA data. Results Seventy-seven patients (64% men, mean ± SD age 56 ± 14 years, median (interquartile range) time on HD 40 (19–72) months, 40% Chinese, 60% British) participated. Participants took fewer steps on HD days compared with non-HD weekdays and weekend days (3402 [95% CI 2665–4140], 4914 [95% CI 3940–5887], 4633 [95% CI 3558–5707] steps/day, respectively, p < 0.001). PA on HD days were less variable than non-HD days, (ICC 0.723–0.839 versus 0.559–0.611) with ≥ 1 HD day and ≥  3 non-HD days required to provide representative data. Using these criteria, the most stringent wear-time retaining ≥ 80% of the sample was ≥7 h. Conclusions At group level, a wear-time of ≥7 h on ≥1HD day and ≥ 3 non-HD days is required to provide reliable PA data whilst retaining an acceptable sample size. PA is low across both HD and non- HD days and future research should focus on interventions designed to increase physical activity in both the intra and interdialytic period.

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