keyword
MENU ▼
Read by QxMD icon Read
search

Uncontrolled manifold

keyword
https://www.readbyqxmd.com/read/27866261/anticipatory-postural-adjustments-and-anticipatory-synergy-adjustments-preparing-to-a-postural-perturbation-with-predictable-and-unpredictable-direction
#1
Daniele Piscitelli, Ali Falaki, Stanislaw Solnik, Mark L Latash
We explored two aspects of feed-forward postural control, anticipatory postural adjustments (APAs) and anticipatory synergy adjustments (ASAs) seen prior to self-triggered unloading with known and unknown direction of the perturbation. In particular, we tested two main hypotheses predicting contrasting changes in APAs and ASAs. The first hypothesis predicted no major changes in ASAs. The second hypothesis predicted delayed APAs with predominance of co-contraction patterns when perturbation direction was unknown...
November 19, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/27778048/optimality-and-stability-of-intentional-and-unintentional-actions-ii-motor-equivalence-and-structure-of-variance
#2
Behnoosh Parsa, Vladimir M Zatsiorsky, Mark L Latash
We address the nature of unintentional changes in performance in two papers. This second paper tested hypotheses related to stability of task-specific performance variables estimated using the framework of the uncontrolled manifold (UCM) hypothesis. Our first hypothesis was that selective stability of performance variables would be observed even when the magnitudes of those variables drifted unintentionally because of the lack of visual feedback. Our second hypothesis was that stability of a variable would depend on the number of explicit task constraints...
October 24, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/27715488/changes-in-multidigit-synergies-and-their-feed-forward-adjustments-in-multiple-sclerosis
#3
Hang Jin Jo, Daniela Mattos, Elisabeth B Lucassen, Xuemei Huang, Mark L Latash
The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS) within the framework of the uncontrolled manifold hypothesis. The specific hypotheses were that both synergy indices and anticipatory synergy adjustments prior to the initiation of a self-paced quick action would be diminished in the patients compared to age-matched controls. The MS patients and age-matched controls (n = 13 in both groups) performed one-finger and multifinger force production tasks involving both accurate steady-state force production and quick force pulses...
August 11, 2016: Journal of Motor Behavior
https://www.readbyqxmd.com/read/27628205/functional-connectivity-in-the-neuromuscular-system-underlying-bimanual-coordination
#4
Ingmar E J de Vries, Andreas Daffertshofer, Dick F Stegeman, Tjeerd W Boonstra
Neural synchrony has been suggested as a mechanism for integrating distributed sensorimotor systems involved in coordinated movement. To test the role of corticomuscular and intermuscular coherence in bimanual coordination, we experimentally manipulated the degree of coordination between hand muscles by varying the sensitivity of the visual feedback to differences in bilateral force. In 16 healthy participants, cortical activity was measured using EEG and muscle activity of the flexor pollicis brevis of both hands using high-density electromyography (HDsEMG)...
December 1, 2016: Journal of Neurophysiology
https://www.readbyqxmd.com/read/27601252/the-synergic-control-of-multi-finger-force-production-stability-of-explicit-and-implicit-task-components
#5
Sasha Reschechtko, Vladimir M Zatsiorsky, Mark L Latash
Manipulating objects with the hands requires the accurate production of resultant forces including shear forces; effective control of these shear forces also requires the production of internal forces normal to the surface of the object(s) being manipulated. In the present study, we investigated multi-finger synergies stabilizing shear and normal components of force, as well as drifts in both components of force, during isometric pressing tasks requiring a specific magnitude of shear force production. We hypothesized that shear and normal forces would evolve similarly in time and also show similar stability properties as assessed by the decomposition of inter-trial variance within the uncontrolled manifold hypothesis...
September 6, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/27546821/anticipatory-synergy-adjustments-reflect-individual-performance-of-feedforward-force-control
#6
Shunta Togo, Hiroshi Imamizu
We grasp and dexterously manipulate an object through multi-digit synergy. In the framework of the uncontrolled manifold (UCM) hypothesis, multi-digit synergy is defined as the coordinated control mechanism of fingers to stabilize variable important for task success, e.g., total force. Previous studies reported anticipatory synergy adjustments (ASAs) that correspond to a drop of the synergy index before a quick change of the total force. The present study compared ASA's properties with individual performances of feedforward force control to investigate a relationship of those...
October 6, 2016: Neuroscience Letters
https://www.readbyqxmd.com/read/27462215/uncontrolled-manifold-reference-feedback-control-of-multi-joint-robot-arms
#7
Shunta Togo, Takahiro Kagawa, Yoji Uno
The brain must coordinate with redundant bodies to perform motion tasks. The aim of the present study is to propose a novel control model that predicts the characteristics of human joint coordination at a behavioral level. To evaluate the joint coordination, an uncontrolled manifold (UCM) analysis that focuses on the trial-to-trial variance of joints has been proposed. The UCM is a nonlinear manifold associated with redundant kinematics. In this study, we directly applied the notion of the UCM to our proposed control model called the "UCM reference feedback control...
2016: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/27334888/the-motor-and-the-brake-of-the-trailing-leg-in-human-walking-leg-force-control-through-ankle-modulation-and-knee-covariance
#8
Megan E Toney, Young-Hui Chang
Human walking is a complex task, and we lack a complete understanding of how the neuromuscular system organizes its numerous muscles and joints to achieve consistent and efficient walking mechanics. Focused control of select influential task-level variables may simplify the higher-level control of steady-state walking and reduce demand on the neuromuscular system. As trailing leg power generation and force application can affect the mechanical efficiency of step-to-step transitions, we investigated how joint torques are organized to control leg force and leg power during human walking...
October 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/27021074/interpersonal-synergies-static-prehension-tasks-performed-by-two-actors
#9
Stanislaw Solnik, Sasha Reschechtko, Yen-Hsun Wu, Vladimir M Zatsiorsky, Mark L Latash
We investigated multidigit synergies stabilizing components of the resultant force vector during joint performance of a static prehension task by two persons as compared to similar tasks performed by a single person using both hands. Subjects transferred the instrumented handle from the right hand to the left hand (one-person condition) or passed that handle to another person (two-person condition) while keeping the handle's position and orientation stationary. Only three digits were involved per hand, the thumb, the index finger, and the middle finger; the forces and moments produced by the digits were measured by six-component sensors...
August 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/26928946/trunk-muscle-coordination-during-upward-and-downward-reaching-in-stroke-survivors
#10
Geetanjali Gera, Kelsey E McGlade, Darcy S Reisman, John Peter Scholz
In this study, we investigated deficits in coordination of trunk muscle modes involved in the stabilization of the trunk's trajectory for reaching upward and downward beyond functional arm length. Trunk muscle activity from 10 stroke survivors (8 men, 2 women; 64.1 ± 10.5 years old) and 9 healthy control subjects (7 men, 2 women; 59.3 ± 9.3 years old) was analyzed. Coordination of trunk muscle modes to stabilize the trunk trajectory was investigated using the uncontrolled manifold (UCM) analysis. The UCM analysis decomposes the variability of muscle modes into good and bad variability...
January 2016: Motor Control
https://www.readbyqxmd.com/read/26898314/coordination-of-muscles-to-control-the-footpath-during-over-ground-walking-in-neurologically-intact-individuals-and-stroke-survivors
#11
Shraddha Srivastava, Pei-Chun Kao, Darcy S Reisman, Jill S Higginson, John P Scholz
The central nervous system (CNS) is believed to use the abundant degrees of freedom of muscles and joints to stabilize a particular task variable important for task success, such as footpath during walking. Stroke survivors often demonstrate impaired balance and high incidences of falls due to increased footpath variability during walking. In the current study, we use the uncontrolled manifold (UCM) approach to investigate the role of motor abundance in stabilizing footpath during swing phase in healthy individuals and stroke survivors...
July 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/26879770/coordination-of-muscle-torques-stabilizes-upright-standing-posture-an-ucm-analysis
#12
Eunse Park, Hendrik Reimann, Gregor Schöner
The control of upright stance is commonly explained on the basis of the single inverted pendulum model (ankle strategy) or the double inverted pendulum model (combination of ankle and hip strategy). Kinematic analysis using the uncontrolled manifold (UCM) approach suggests, however, that stability in upright standing results from coordinated movement of multiple joints. This is based on evidence that postural sway induces more variance in joint configurations that leave the body position in space invariant than in joint configurations that move the body in space...
June 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/26784706/motor-abundance-and-control-structure-in-the-golf-swing
#13
A Morrison, D McGrath, E S Wallace
Variability and control structure are under-represented areas of golf swing research. This study investigated the use of the abundant degrees of freedom in the golf swing of high and intermediate skilled golfers using uncontrolled manifold (UCM) analysis. The variance parallel to (VUCM) and orthogonal to (VOrth) the UCM with respect to the orientation and location of the clubhead were calculated. The higher skilled golfers had proportionally higher values of VUCM than lower skilled players for all measured outcome variables...
April 2016: Human Movement Science
https://www.readbyqxmd.com/read/26608514/relationship-of-diminished-interjoint-coordination-after-stroke-to-hand-path-consistency
#14
Geetanjali Gera, Sandra Maria Sbeghen Ferreira Freitas, John Peter Scholz
Differences between 12 left-brain (LCVA, 65.4 ± 11.7 years old) and 10 right-brain (RCVA, 61 ± 12.1 years old) chronic stroke survivors and 10 age-matched control adults in coordinating specific joint motions of the arm to stabilize hand path when reaching to a central target were investigated in this study. The importance of coordinating joints to stabilize hand path was tested by comparing results from uncontrolled manifold (UCM) analysis performed on experimental data versus simulated data where the covariation (coordination) between particular joint motions was removed from the original data set...
March 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/26474043/normalized-index-of-synergy-for-evaluating-the-coordination-of-motor-commands
#15
Shunta Togo, Hiroshi Imamizu
Humans perform various motor tasks by coordinating the redundant motor elements in their bodies. The coordination of motor outputs is produced by motor commands, as well properties of the musculoskeletal system. The aim of this study was to dissociate the coordination of motor commands from motor outputs. First, we conducted simulation experiments where the total elbow torque was generated by a model of a simple human right and left elbow with redundant muscles. The results demonstrated that muscle tension with signal-dependent noise formed a coordinated structure of trial-to-trial variability of muscle tension...
2015: PloS One
https://www.readbyqxmd.com/read/26052696/can-discrete-joint-action-be-synergistic-studying-the-stabilization-of-interpersonal-hand-coordination
#16
Veronica Romero, Rachel Kallen, Michael A Riley, Michael J Richardson
The human perceptual-motor system is tightly coupled to the physical and informational dynamics of a task environment. These dynamics operate to constrain the high-dimensional order of the human movement system into low-dimensional, task-specific synergies-functional groupings of structural elements that are temporarily constrained to act as a single coordinated unit. The aim of the current study was to determine whether synergistic processes operate when coacting individuals coordinate to perform a discrete joint-action task...
October 2015: Journal of Experimental Psychology. Human Perception and Performance
https://www.readbyqxmd.com/read/26003449/challenging-gait-leads-to-stronger-lower-limb-kinematic-synergies-the-effects-of-walking-within-a-more-narrow-pathway
#17
N J Rosenblatt, M L Latash, C P Hurt, M D Grabiner
Previous studies using the uncontrolled manifold (UCM) analysis demonstrated that during the swing phase of gait, multi-joint kinematic synergies act to stabilize, i.e., minimize the variance of, the mediolateral trajectory of the swinging limb. Importantly, these synergies are strongest during midswing, suggesting that during gait, individuals may employ strategies to avoid collisions between the limbs at this instance. The purpose of the current study was to test this hypothesis by quantifying whether the synergy index (ΔV) during the middle period of the swing phase of treadmill walking was affected when the width of the treadmill belt was narrowed, a task expected to increase the risk of limb collisions...
July 23, 2015: Neuroscience Letters
https://www.readbyqxmd.com/read/26003130/carry-over-coarticulation-in-joint-angles
#18
Eva Hansen, Britta Grimme, Hendrik Reimann, Gregor Schöner
Coarticulation indicates a dependence of a movement segment on a preceding segment (carry-over coarticulation) or on the segment that follows (anticipatory coarticulation). Here we study coarticulation in multidegrees of freedom human arm movements. We asked participants to transport a cylinder from a starting position to a center target and on to a final target. In this naturalistic setting, the human arm has ten degrees of freedom and is thus comfortably redundant for the task. We studied coarticulation by comparing movements between the same spatial locations that were either preceded by different end-effector paths (carry-over coarticulation) or followed by different end-effector paths (anticipatory coarticulation)...
September 2015: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/25970465/physical-demand-but-not-dexterity-is-associated-with-motor-flexibility-during-rapid-reaching-in-healthy-young-adults
#19
Christian Greve, Tibor Hortobàgyi, Raoul M Bongers
Healthy humans are able to place light and heavy objects in small and large target locations with remarkable accuracy. Here we examine how dexterity demand and physical demand affect flexibility in joint coordination and end-effector kinematics when healthy young adults perform an upper extremity reaching task. We manipulated dexterity demand by changing target size and physical demand by increasing external resistance to reaching. Uncontrolled manifold analysis was used to decompose variability in joint coordination patterns into variability stabilizing the end-effector and variability de-stabilizing the end-effector during reaching...
2015: PloS One
https://www.readbyqxmd.com/read/25931471/hand-motor-control-maturing-an-immature-science
#20
Kelly J Cole
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...
April 2015: Motor Control
keyword
keyword
36979
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"