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.

scholarly journals Motor control theories and their applications

Medicina ◽  
2010 ◽  
Vol 46 (6) ◽  
pp. 382 ◽  
Author(s):  
Mark Latash ◽  
Mindy Levin ◽  
John Scholz ◽  
Gregor Schöner
Keyword(s):  
Motor Control ◽  
Equilibrium Point ◽  
Movement Disorders ◽  
Stretch Reflex ◽  
Uncontrolled Manifold ◽  
Uncontrolled Manifold Hypothesis ◽  
Equilibrium Point Hypothesis ◽  
Performance Variables ◽  
Neural Computations ◽  
Technical Details

We describe several infl uential hypotheses in the field of motor control including the equilibrium-point (referent confi guration) hypothesis, the uncontrolled manifold hypothesis, and the idea of synergies based on the principle of motor abundance. The equilibrium-point hypothesis is based on the idea of control with thresholds for activation of neuronal pools; it provides a framework for analysis of both voluntary and involuntary movements. In particular, control of a single muscle can be adequately described with changes in the threshold of motor unit recruitment during slow muscle stretch (threshold of the tonic stretch reflex). Unlike the ideas of internal models, the equilibrium-point hypothesis does not assume neural computations of mechanical variables. The uncontrolled manifold hypothesis is based on the dynamic system approach to movements; it offers a toolbox to analyze synergic changes within redundant sets of elements related to stabilization of potentially important performance variables. The referent confi guration hypothesis and the principle of abundance can be naturally combined into a single coherent scheme of control of multi-element systems. A body of experimental data on healthy persons and patients with movement disorders are reviewed in support of the mentioned hypotheses. In particular, movement disorders associated with spasticity are considered as consequences of an impaired ability to shift threshold of the tonic stretch reflex within the whole normal range. Technical details and applications of the mentioned hypo theses to studies of motor learning are described. We view the mentioned hypotheses as the most promising ones in the field of motor control, based on a solid physical and neurophysiological foundation.

Further explorations of the empirical and theoretical aspects of the emulation theory

2004 ◽  
Vol 27 (3) ◽  
pp. 425-435 ◽  
Author(s):  
Rick Grush
Keyword(s):  
Motor Control ◽  
Equilibrium Point ◽  
Kalman Filtering ◽  
Empirical Data ◽  
Empirical Support ◽  
Target Article

The emulation theory of representation articulated in the target article is further explained and explored in this response to commentaries. Major topics include: the irrelevance of equilibrium-point and related models of motor control to the theory; clarification of the particular sense of “representation” which the emulation theory of representation is an account of; the relation between the emulation framework and Kalman filtering; and addressing the empirical data considered to be in conflict with the emulation theory. In addition, I discuss the further empirical support for the emulation theory provided by some commentators, as well as a number of suggested theoretical applications.

scholarly journals Understanding and Synergy: A Single Concept at Different Levels of Analysis?

2021 ◽  
Vol 15 ◽  
Author(s):  
Mark L. Latash
Keyword(s):  
Neural Control ◽  
Laws Of Nature ◽  
Hierarchical Control ◽  
Motor Units ◽  
Optimality Criteria ◽  
Uncontrolled Manifold ◽  
Biological Phenomena ◽  
Atypical Development ◽  
High Level ◽  
Large Groups

Biological systems differ from the inanimate world in their behaviors ranging from simple movements to coordinated purposeful actions by large groups of muscles, to perception of the world based on signals of different modalities, to cognitive acts, and to the role of self-imposed constraints such as laws of ethics. Respectively, depending on the behavior of interest, studies of biological objects based on laws of nature (physics) have to deal with different salient sets of variables and parameters. Understanding is a high-level concept, and its analysis has been linked to other high-level concepts such as “mental model” and “meaning”. Attempts to analyze understanding based on laws of nature are an example of the top-down approach. Studies of the neural control of movements represent an opposite, bottom-up approach, which starts at the interface with classical physics of the inanimate world and operates with traditional concepts such as forces, coordinates, etc. There are common features shared by the two approaches. In particular, both assume organizations of large groups of elements into task-specific groups, which can be described with only a handful of salient variables. Both assume optimality criteria that allow the emergence of families of solutions to typical tasks. Both assume predictive processes reflected in anticipatory adjustments to actions (motor and non-motor). Both recognize the importance of generating dynamically stable solutions. The recent progress in studies of the neural control of movements has led to a theory of hierarchical control with spatial referent coordinates for the effectors. This theory, in combination with the uncontrolled manifold hypothesis, allows quantifying the stability of actions with respect to salient variables. This approach has been used in the analysis of motor learning, changes in movements with typical and atypical development and with aging, and impaired actions by patients with various neurological disorders. It has been developed to address issues of kinesthetic perception. There seems to be hope that the two counter-directional approaches will meet and result in a single theoretical scheme encompassing biological phenomena from figuring out the best next move in a chess position to activating motor units appropriate for implementing that move on the chessboard.

Hand Motor Control: Maturing an Immature Science

Motor Control ◽  
2015 ◽  
Vol 19 (2) ◽  
pp. 131-134 ◽  
Author(s):  
Kelly J. Cole
Keyword(s):  
Motor Control ◽  
Early Stage ◽  
Uncontrolled Manifold ◽  
Configuration Theory ◽  
Referent Configuration ◽  
Target Article ◽  
Bona Fide ◽  
Hand Motor Control

In the target article Mark Latash has argued that there is but a single bona-fide theory for hand motor control (referent configuration theory). If this is true, and research is often phenomenological, then we must admit that the science of hand motor control is immature. While describing observations under varying conditions is a crucial (but early) stage of the science of any field, it is also true that the key to maturing any science is to vigorously subject extant theories and budding laws to critical experimentation. If competing theories are absent at the present time is it time for scientists to focus their efforts on maturing the science of hand motor control through critical testing of this long-standing theory (and related collections of knowledge such as the uncontrolled manifold)?

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.

Motor Control: Creating a Natural Science of Biological Movement

2021 ◽  
pp. 1-7
Author(s):  
Mark L. Latash
Keyword(s):  
Motor Control ◽  
Natural Science ◽  
Uncontrolled Manifold ◽  
Uncontrolled Manifold Hypothesis ◽  
The Past ◽  
Spatial Coordinates ◽  
Applied Fields ◽  
The Brain ◽  
Recent Version ◽  
Theoretical Developments

Motor control is a young and aspiring field of natural science. Over the past 40 years, it has become an established field of study with several important theoretical developments, including the equilibrium-point hypothesis and its more recent version known as the control with referent spatial coordinates, the principle of abundance, the uncontrolled manifold hypothesis, and the concept of dynamic neural field as the means of task formulation. Important experimental advances have included the exploration of the notion of synergies, the links between descending signals from the brain and referent coordinates of the effectors, and applications of motor control principles to analysis of disordered movements. Further maturation of motor control requires focusing on theory-driven studies. It promises fruitful applications to applied fields such as movement disorders and rehabilitation.

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 Biomechanics as a window into the neural control of movement

2016 ◽  
Vol 52 (1) ◽  
pp. 7-20 ◽  
Author(s):  
Mark L. Latash
Keyword(s):  
Motor Control ◽  
Neural Control ◽  
Laws Of Nature ◽  
Motor Program ◽  
Uncontrolled Manifold ◽  
Living Systems ◽  
Motor Synergies ◽  
The Central Nervous System ◽  
Definition Of ◽  
Neural Control Of Movement

Abstract Biomechanics and motor control are discussed as parts of a more general science, physics of living systems. Major problems of biomechanics deal with exact definition of variables and their experimental measurement. In motor control, major problems are associated with formulating currently unknown laws of nature specific for movements by biological objects. Mechanics-based hypotheses in motor control, such as those originating from notions of a generalized motor program and internal models, are non-physical. The famous problem of motor redundancy is wrongly formulated; it has to be replaced by the principle of abundance, which does not pose computational problems for the central nervous system. Biomechanical methods play a central role in motor control studies. This is illustrated with studies with the reconstruction of hypothetical control variables and those exploring motor synergies within the framework of the uncontrolled manifold hypothesis. Biomechanics and motor control have to merge into physics of living systems, and the earlier this process starts the better.

scholarly journals NEURAL ACTIVITY PROFILES ASSOCIATED WITH ACL INJURY-RISK MECHANICS IN ECOLOGICAL SPORT SPECIFIC VIRTUAL REALITY

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0015
Author(s):  
Dustin R. Grooms ◽  
Jed A. Diekfuss ◽  
Alexis B. Slutsky-Ganesh ◽  
Cody R. Criss ◽  
Manish Anand ◽  
...  
Keyword(s):  
Motor Control ◽  
Neural Activity ◽  
Injury Risk ◽  
Neural Control ◽  
Acl Injury ◽  
Initial Contact ◽  
Leg Press ◽  
Visual Spatial ◽  
Peak Knee ◽  
Acl Injury Risk

Background: Anterior cruciate ligament (ACL) injury is secondary to a multifactorial etiology encompassing anatomical, biological, mechanical, and neurological factors. The nature of the injury being primarily due to non-contact mechanics further implicates neural control as a key injury-risk factor, though it has received considerably less study. Purpose: To determine the contribution of neural activity to injury-risk mechanics in ecological sport-specific VR landing scenarios. Methods: Ten female high-school soccer players (15.5±0.85 years; 165.0±6.09 cm; 59.1±11.84 kg) completed a neuroimaging session to capture neural activity during a bilateral leg press and a 3D biomechanics session performing a header within a VR soccer scenario. The bilateral leg press involved four 30 s blocks of repeated bilateral leg presses paced to a metronome beat of 1.2 Hz with 30 s rest between blocks. The VR soccer scenario simulated a corner-kick, requiring the participant to jump and head a virtual soccer ball into a virtual goal (Figure 1A-E). Initial contact and peak knee flexion and abduction angles were extracted during the landing from the header as injury-risk variables of interest and were correlated with neural activity. Results: Evidenced in Table 1 and Figure 1 (bottom row), increased initial contact abduction, increased peak abduction, and decreased peak flexion were associated with increased sensory, visual-spatial, and cerebellar activity (r2= 0.42-0.57, p corrected < .05, z max > 3.1, table & figure 1). Decreased initial contact flexion was associated with increased frontal cortex activity (r2= 0.68, p corrected < .05, z max > 3.1). Conclusion: Reduced neural efficiency (increased activation) of key regions that integrate proprioceptive, visual-spatial, and neurocognitive activity for motor control may influence injury-risk mechanics in sport. The regions found to increase in activity in relation to higher injury-risk mechanics are typically activated to assist with spatial navigation, environmental interaction, and precise motor control. The requirement for athletes to increase their activity for more basic knee motor control may result in fewer neural resources available to maintain knee joint alignment, allocate environmental attention, and handle increased motor coordination demands. These data indicate that strategies to enhance efficiency of visual-spatial and cognitive-motor control during high demand sporting activities is warranted to improve ACL injury-risk reduction. [Figure: see text][Table: see text]

Does the nervous system use equilibrium-point control to guide single and multiple joint movements?

1992 ◽  
Vol 15 (04) ◽  
pp. 603-613 ◽  
Author(s):  
E. Bizzi ◽  
N. Hogan ◽  
F. A. Mussa-Ivaldi ◽  
S. Giszter
Keyword(s):  
Nervous System ◽  
Equilibrium Point ◽  
System Use ◽  
Point Control
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