Examining contemporary motor control theories from the perspective of degrees of freedom

2012 ◽  
Vol 60 (2) ◽  
pp. 138-143 ◽  
Author(s):  
Kuan-Yi Li
Keyword(s):  
Motor Control ◽  
Degrees Of Freedom ◽  
Control Theories

scholarly journals Postural Synergy-Based Exoskeleton Reproducing Natural Human Movements to Improve Upper Limb Motor Control after Stroke

2020 ◽  
Author(s):  
Chang He ◽  
Cai-Hua Xiong ◽  
Ze-Jian Chen ◽  
Wei Fan ◽  
Xiao-Lin Huang
Keyword(s):  
Motor Control ◽  
Upper Limb ◽  
Degrees Of Freedom ◽  
Response Rate ◽  
Human Movement ◽  
Interaction Force ◽  
Human Anatomy ◽  
Clinical Trial Registration ◽  
Upper Limb Exoskeleton ◽  
Human Movements

Abstract Background: Upper limb exoskeletons have drawn significant attention in neurorehabilitation because of anthropomorphic mechanical structure analogous to human anatomy. Whereas, the training movements are typically underorganized because most exoskeletons only control the movement of the hand in space, without considering rehabilitation of joint motion, particularly inter-joint postural synergy. The purposes of this study were to explore the application of a postural synergy-based exoskeleton (Armule) reproducing natural human movements for robot-assisted neurorehabilitation and to preliminarily assess its effect on patients' upper limb motor control after stroke. Methods: We developed a novel upper limb exoskeleton based on the concept of postural synergy, which provided five degrees of freedom (DOF) , natural human movements of the upper limb. Eight participants with hemiplegia due to a first-ever, unilateral stroke were recruited and included. They participated in exoskeleton therapy sessions 45 minutes/day, 5 days/week for 4 weeks, with passive/active training under anthropomorphic trajectories and postures. The primary outcome was the Fugl-Meyer Assessment for Upper Extremities (FMA-UE). The secondary outcomes were the Action Research Arm Test(ARAT), modified Barthel Index (mBI) , and exoskeleton kinematic as well as interaction force metrics: motion smoothness in the joint space, postural synergy error, interaction force smoothness, and the intent response rate. Results: After the 4-weeks intervention, all subjects showed significant improvements in the following clinical measures: the FMA-UE ( p =0.02), the ARAT ( p =0.003), and the mBI score ( p <0.001). Besides, all subjects showed significant improvements in motion smoothness ( p =0.004), postural synergy error ( p =0.014), interaction force smoothness ( p =0.004), and the intent response rate ( p =0.008). Conclusions: The subjects were well adapted to our device that assisted in completing functional movements with natural human movement characteristics. The results of the preliminary clinical intervention indicate that the Armule exoskeleton improves individuals’ motor control and activities of daily living (ADL) function after stroke, which might be associated with kinematic and interaction force optimization and postural synergy modification during functional tasks. Clinical trial registration: ChiCTR, ChiCTR1900026656; Date of registration: October 17, 2019. http://www.chictr.org.cn/showproj.aspx?proj=44420

Motor Control Theories — Insights for therapists

Physiotherapy ◽  
1997 ◽  
Vol 83 (8) ◽  
pp. 397-405 ◽  
Author(s):  
Patricia Bate
Keyword(s):  
Motor Control ◽  
Control Theories

scholarly journals Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis

2008 ◽  
Vol 19 (1) ◽  
pp. 3-24 ◽  
Author(s):  
Mark Latash
Keyword(s):  
Motor Control ◽  
Equilibrium Point ◽  
Voluntary Movements ◽  
Motor Programs ◽  
Equilibrium Point Hypothesis ◽  
Motor Synergies ◽  
Recent Developments ◽  
Active Motor ◽  
Control Theories

Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point HypothesisThis brief review analyzes the evolution of motor control theories along two lines that emphasize active (motor programs) and reactive (reflexes) features of voluntary movements. It suggests that the only contemporary hypothesis that integrates both approaches in a fruitful way is the equilibrium-point hypothesis. Physical, physiological, and behavioral foundations of the EP-hypothesis are considered as well as relations between the EP-hypothesis and the recent developments of the notion of motor synergies. The paper ends with a brief review of the criticisms of the EP-hypothesis and challenges that the hypothesis faces at this time.

Adaptability of innate motor patterns and motor control mechanisms

1986 ◽  
Vol 9 (4) ◽  
pp. 585-599 ◽  
Author(s):  
M. B. Berkinblit ◽  
A. G. Feldman ◽  
O. I. Fukson
Keyword(s):  
Nervous System ◽  
Motor Control ◽  
Degrees Of Freedom ◽  
Behavioral Plasticity ◽  
Motor Behavior ◽  
Voluntary Control ◽  
Control Mechanisms ◽  
Motor Equivalence ◽  
Motor Patterns ◽  
Dynamic Components

AbstractThe following factors underlying behavioral plasticity are discussed: (1) reflex adaptability and its role in the voluntary control of movement, (2) degrees of freedom and motor equivalence, and (3) the problem of the discrete organization of motor behavior. Our discussion concerns a variety of innate motor patterns, with emphasis on the wiping reflex in the frog.It is proposed that central regulation of stretch reflex thresholds governs voluntary control over muscle force and length. This suggestion is an integral part of the equilibrium-point hypothesis, two versions of which are compared.Kinematic analysis of the wiping reflex in the spinal frog has shown that each stimulated skin site is associated with a group of different but equally effective trajectories directed to the target site. Such phenomena reflect the principle of motor equivalence -the capacity of the neuronal structures responsible for movement to select one or another of a set of possible trajectories leading to the goal. Redundancy of degrees of freedom at the neuronal level as well as at the mechanical level of the body's joints makes motor equivalence possible. This sort of equivalence accommodates the overall flexibility of motor behavior.An integrated behavioral act or a single movement consists of dynamic components. We distinguish six components for the wiping reflex, each associated with a certain functional goal, specific body positions, and motor-equivalent movement patterns. The nervous system can combine the available components in various ways in forming integrated behavioral sequences. The significance of command neuronal organization is discussed with respect to (1) the combinatory strategy of the nervous system and (2) the relation between continuous and discrete forms of motor control. We conclude that voluntary movements are effected by the central nervous system with the help of the mechanisms that underlie the variability and modifiability of innate motor patterns.

scholarly journals Computational approaches to motor learning by imitation

2003 ◽  
Vol 358 (1431) ◽  
pp. 537-547 ◽  
Author(s):  
Stefan Schaal ◽  
Auke Ijspeert ◽  
Aude Billard
Keyword(s):  
Motor Control ◽  
Degrees Of Freedom ◽  
Spatial Information ◽  
Point Of View ◽  
Performance Criteria ◽  
Future Research ◽  
Computational Point ◽  
Pose Tracking ◽  
Active Research ◽  
Learning By Imitation

Movement imitation requires a complex set of mechanisms that map an observed movement of a teacher onto one's own movement apparatus. Relevant problems include movement recognition, pose estimation, pose tracking, body correspondence, coordinate transformation from external to egocentric space, matching of observed against previously learned movement, resolution of redundant degrees–of–freedom that are unconstrained by the observation, suitable movement representations for imitation, modularization of motor control, etc. All of these topics by themselves are active research problems in computational and neurobiological sciences, such that their combination into a complete imitation system remains a daunting undertaking—indeed, one could argue that we need to understand the complete perception–action loop. As a strategy to untangle the complexity of imitation, this paper will examine imitation purely from a computational point of view, i.e. we will review statistical and mathematical approaches that have been suggested for tackling parts of the imitation problem, and discuss their merits, disadvantages and underlying principles. Given the focus on action recognition of other contributions in this special issue, this paper will primarily emphasize the motor side of imitation, assuming that a perceptual system has already identified important features of a demonstrated movement and created their corresponding spatial information. Based on the formalization of motor control in terms of control policies and their associated performance criteria, useful taxonomies of imitation learning can be generated that clarify different approaches and future research directions.

Motor Control and Learning in the North American Society for the Psychology of Sport and Physical Activity (NASPSPA): The First 40 Years

2017 ◽  
Vol 6 (3) ◽  
pp. 221-231 ◽  
Author(s):  
Robert W. Christina
Keyword(s):  
Motor Control ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Attentional Focus ◽  
Mental Practice ◽  
North American Society ◽  
Biological Mechanisms ◽  
The North ◽  
Human Motor ◽  
American Society

By 1967, motor control and learning researchers had adopted an information processing (IP) approach. Central to that research was understanding how movement information was processed, coded, stored, and represented in memory. It also was centered on understanding motor control and learning in terms of Fitts’ law, closed-loop and schema theories, motor programs, contextual interference, modeling, mental practice, attentional focus, and how practice and augmented feedback could be organized to optimize learning. Our constraints-based research from the 1980s into the 2000s searched for principles of “self-organization”, and answers to the degrees-of-freedom problem, that is, how the human motor system with so many independent parts could be controlled without the need for an executive decision maker as proposed by the IP approach. By 2007 we were thinking about where the IP and constraints-based views were divergent and complementary, and whether neural-based models could bring together the behavior and biological mechanisms underlying the processes of motor control and learning.

Two functionally different synergies during arm reaching movements involving the trunk

1995 ◽  
Vol 73 (5) ◽  
pp. 2120-2122 ◽  
Author(s):  
S. Ma ◽  
A. G. Feldman
Keyword(s):  
Motor Control ◽  
Degrees Of Freedom ◽  
Arm Movements ◽  
The Other ◽  
Reaching Movements ◽  
Positional Error ◽  
Trunk Motion ◽  
Arm Reaching ◽  
Trunk Movements ◽  
The Right

1. To address the problem of the coordination of a redundant number of degrees of freedom in motor control, we analyzed the influence of voluntary trunk movements on the arm endpoint trajectory during reaching. 2. Subjects made fast noncorrected planar movements of the right arm from a near to a far target located in the ipsilateral work space at a 45 degrees angle to the sagittal midline of the trunk. These reaching movements were combined with a forward or a backward sagittal motion of the trunk. 3. The direction, positional error, curvature, and velocity profile of the endpoint trajectory remained invariant regardless of trunk movements. Trunk motion preceded endpoint motion by approximately 175 ms, continued during endpoint movement to the target, and outlasted it by 200 ms. This sequence of trunk and arm movements was observed regardless of the direction of the endpoint trajectory (to or from the far target) or trunk movements (forward or backward). 4. Our data imply that reaching movements result from two control synergies: one coordinates trunk and arm movements leaving the position of the endpoint unchanged, and the other produces interjoint coordination shifting the arm endpoint to the target. The use of functionally different synergies may underlie a solution of the redundancy problem.

scholarly journals Functional connectivity between the cerebellum and somatosensory areas implements the attenuation of self-generated touch

2019 ◽  
Author(s):  
Konstantina Kilteni ◽  
H. Henrik Ehrsson
Keyword(s):  
Magnetic Resonance Imaging ◽  
Motor Control ◽  
Magnetic Resonance ◽  
Functional Connectivity ◽  
Functional Magnetic Resonance Imaging ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Neural Basis ◽  
Somatosensory Areas ◽  
Control Theories

AbstractSince the early 1970s, numerous behavioral studies have shown that self-generated touch feels less intense than the same touch applied externally. Computational motor control theories have suggested that cerebellar internal models predict the somatosensory consequences of our movements and that these predictions attenuate the perception of the actual touch. Despite this influential theoretical framework, little is known about the neural basis of this predictive attenuation. This is due to the limited number of neuroimaging studies, the presence of conflicting results about the role and the location of cerebellar activity, and the lack of behavioral measures accompanying the neural findings. Here, we combined psychophysics with functional magnetic resonance imaging to detect the neural processes underlying somatosensory attenuation in male and female healthy human participants. Activity in bilateral secondary somatosensory areas was attenuated when the touch was presented during a self-generated movement (self-generated touch) than in the absence of movement (external touch). An additional attenuation effect was observed in the cerebellum that is ipsilateral to the passive limb receiving the touch. Importantly, we further found that the degree of functional connectivity between the ipsilateral cerebellum and the contralateral primary and bilateral secondary somatosensory areas was linearly and positively related to the degree of behaviorally assessed attenuation; that is, the more participants perceptually attenuated their self-generated touches, the stronger this corticocerebellar coupling. Collectively, these results suggest that the ipsilateral cerebellum is fundamental in predicting self-generated touch and that this structure implements somatosensory attenuation via its functional connectivity with somatosensory areas.Significance statementWhen we touch our hand with the other, the resulting sensation feels less intense than when another person or a machine touches our hand with the same intensity. Early computational motor control theories have proposed that the cerebellum predicts and cancels the sensory consequences of our movements; however, the neural correlates of this cancelation remain unknown. By means of functional magnetic resonance imaging, we show that the more participants attenuate the perception of their self-generated touch, the stronger the functional connectivity between the cerebellum and the somatosensory cortical areas. This provides conclusive evidence about the role of the cerebellum in predicting the sensory feedback of our movements and in attenuating the associated percepts via its connections to early somatosensory areas.

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