keyword
MENU ▼
Read by QxMD icon Read
search

Uncontrolled manifold

keyword
https://www.readbyqxmd.com/read/28939197/uncontrolled-manifold-hypothesis-organization-of-leg-joint-variance-in-humans-while-walking-in-a-wide-range-of-speeds
#1
Monaco Vito, Tropea Peppino, Lucio A Rinaldi, Micera Silvestro
This study aimed at investigating the organization of joint angle variability during walking by using the uncontrolled manifold (UCM) theory. We tested two hypotheses: i. the coordinative mechanism underlying joint angle variance during the stance phase is compatible with a kinematic synergy that stabilizes the centre of mass (CoM) position; ii. the walking speed affects the variance components onto and orthogonal to the UCM. Eight healthy subjects (26.0±2.0years old) steadily walked on a treadmill at five normalised speeds (from 0...
September 19, 2017: Human Movement Science
https://www.readbyqxmd.com/read/28936720/development-of-finger-force-coordination-in-children
#2
Sharon Shaklai, Aviva Mimouni-Bloch, Moran Levin, Jason Friedman
Coordination is often observed as body parts moving together. However, when producing force with multiple fingers, the optimal coordination is not to produce similar forces with each finger, but rather for each finger to correct mistakes of other fingers. In this study, we aim to determine whether and how this skill develops in children aged 4-12 years. We measured this sort of coordination using the uncontrolled manifold hypothesis (UCM). We recorded finger forces produced by 60 typically developing children aged between 4 and 12 years in a finger-pressing task...
September 21, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28931612/cue-induced-changes-in-the-stability-of-finger-force-production-tasks-revealed-by-the-uncontrolled-manifold-analysis
#3
Satyajit S Ambike, Mitchell Tillman
A motor system configured to maximize the stability of its current state cannot dexterously transition between states. Yet, we routinely resolve the stability-dexterity conflict and rapidly change our current behavior without allowing it to become unstable prior to the desired transition. The phenomenon called anticipatory synergy adjustment (ASA) partly describes how the central nervous system handles this conflict. ASA is a continuous decrease in the stability of the current motor state beginning 150-400 ms prior to a rapid state transition accomplished using redundant sets of motor inputs (more input variables than task-specific output variables)...
September 20, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28924748/a-multi-joint-model-of-quiet-upright-stance-accounts-for-the-uncontrolled-manifold-structure-of-joint-variance
#4
Hendrik Reimann, Gregor Schöner
The upright body in quiet stance is usually modeled as a single-link inverted pendulum. This agrees with most of the relevant sensory organs being at the far end of the pendulum, i.e., the eyes and the vestibular system in the head. Movement of the body in quiet stance has often been explained in terms of the "ankle strategy," where most movement is generated by the ankle musculature, while more proximal muscle groups are only rarely activated for faster movements or in response to perturbations, for instance, by flexing at the hips in what has been called the "hip strategy...
September 18, 2017: Biological Cybernetics
https://www.readbyqxmd.com/read/28915097/synergies-and-motor-equivalence-in-voluntary-sway-tasks-the-effects-of-visual-and-mechanical-constraints
#5
Mariusz P Furmanek, Stanisław Solnik, Daniele Piscitelli, Omid Rasouli, Ali Falaki, Mark L Latash
The authors used two analyses developed within the framework of the uncontrolled manifold hypothesis to quantify multimuscle synergies during voluntary body sway: analysis of intertrial variance and analysis of motor equivalence with respect to the center of pressure (COP) trajectory. Participants performed voluntary sway tasks in the anteroposterior direction at 0.33 and 0.66 Hz. Muscle groups were identified in the space of muscle activations and used as elemental variables in the synergy analyses. Changing mechanical and vision feedback-based constraints led to significant changes in indices of sway performance such as COP deviations in the uninstructed, mediolateral direction and indices of spontaneous postural sway...
September 15, 2017: Journal of Motor Behavior
https://www.readbyqxmd.com/read/28904102/stability-of-hand-force-production-i-hand-level-control-variables-and-multi-finger-synergies
#6
Sasha Reschechtko, Mark L Latash
We combined the theory of neural control of movement with referent coordinates and the uncontrolled manifold hypothesis to explore synergies stabilizing the hand action in accurate four-finger pressing tasks. In particular, we tested a hypothesis on two classes of synergies - those among the four fingers and those within a pair of control variables - stabilizing hand action under visual feedback and disappearing without visual feedback. Subjects performed four-finger total force and moment production tasks under visual feedback; the feedback was later partially or completely removed...
September 13, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28869185/gait-variability-and-motor-control-in-patients-with-knee-osteoarthritis-as-measured-by-the-uncontrolled-manifold-technique
#7
Gwenllian Fflur Tawy, Philip Rowe, Leela Biant
Knee osteoarthritis (OA) causes pain, reduced muscular strength and stiffness of the affected joint. In response, the motor control mechanism is altered, potentially compromising stability during acts of daily living. Reduced walking stability can be quantified in terms of gait variability. This study therefore aimed to identify and quantify the effects of knee arthritis on gait variability. Fifty adults (25 males/25 females) with end-stage OA of the knee sufficiently symptomatic to require joint replacement, walked on a self-paced treadmill for 2min...
August 18, 2017: Gait & Posture
https://www.readbyqxmd.com/read/28674489/multi-finger-interaction-and-synergies-in-finger-flexion-and-extension-force-production
#8
Jaebum Park, Dayuan Xu
The aim of this study was to discover finger interaction indices during single-finger ramp tasks and multi-finger coordination during a steady state force production in two directions, flexion, and extension. Furthermore, the indices of anticipatory adjustment of elemental variables (i.e., finger forces) prior to a quick pulse force production were quantified. It is currently unknown whether the organization and anticipatory modulation of stability properties are affected by force directions and strengths of in multi-finger actions...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28455740/motor-equivalence-and-structure-of-variance-multi-muscle-postural-synergies-in-parkinson-s-disease
#9
Ali Falaki, Xuemei Huang, Mechelle M Lewis, Mark L Latash
We explored posture-stabilizing multi-muscle synergies with two methods of analysis of multi-element, abundant systems: (1) Analysis of inter-cycle variance; and (2) Analysis of motor equivalence, both quantified within the framework of the uncontrolled manifold (UCM) hypothesis. Data collected in two earlier studies of patients with Parkinson's disease (PD) were re-analyzed. One study compared synergies in the space of muscle modes (muscle groups with parallel scaling of activation) during tasks performed by early-stage PD patients and controls...
July 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28425057/quantifying-synergies-in-two-versus-one-situations-in-team-sports-an-example-from-rugby-union
#10
P Passos, J Milho, C Button
Collective behaviors in team sports result in players forming interpersonal synergies that contribute to performance goals. Because of the huge amount of variables that continuously constrain players' behavior during a game, the way that these synergies are formed remain unclear. Our aim was to quantify interpersonal synergies in the team sport of Rugby Union. For that purpose we used the Uncontrolled Manifold Hypothesis (UCM) to identify interpersonal synergies that are formed between ball carrier and support player in two-versus-one situations in Rugby Union...
April 19, 2017: Behavior Research Methods
https://www.readbyqxmd.com/read/28423977/age-associated-differences-in-motor-output-variability-and-coordination-during-the-simultaneous-dorsiflexion-of-both-feet
#11
Amanda Marchini, Rafael Pereira, Wellington Pedroso, Evangelos Christou, Osmar Pinto Neto
Older adults are more variable than young adults on tasks that demand the simultaneous control of more than one effector, and the difference between age groups may be related to their different capacity of coordinating the force output of the involved effectors. The goal of this study was to determine whether age-associated differences in motor output variability during tasks involving the simultaneous dorsiflexion of two feet can be partially explained by differences in coordination and possibly attenuated by physical training...
April 19, 2017: Somatosensory & Motor Research
https://www.readbyqxmd.com/read/28293798/old-adults-preserve-motor-flexibility-during-rapid-reaching
#12
Christian Greve, Tibor Hortobágyi, Raoul M Bongers
PURPOSE: Our ability to flexibly coordinate the available degrees of freedom allows us to perform activities of daily living under various task constraints. Healthy old adults exhibit subclinical peripheral and central nervous system dysfunctions, possibly compromising the flexibility in inter-joint coordination during voluntary movements and the ability to adapt to varying task constraints. METHOD: We examined how healthy old (75.4 ± 5.2 years, n = 14) compared with young adults (24...
May 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28246971/bilateral-synergy-as-an-index-of-force-coordination-in-chronic-stroke
#13
Nyeonju Kang, James H Cauraugh
Dysfunction in bilateral coordination post-stroke is responsible for impaired bilateral movements. This study examined bilateral synergies using the uncontrolled manifold (UCM) approach while individuals in a chronic stage after stroke executed bilateral isometric force control at three submaximal force levels. Nine patients with stroke and nine age-matched healthy controls performed 24 trials of wrist and fingers extension at 5, 25, and 50% of MVC. The UCM findings revealed: (a) decreased bilateral synergies in patients with stroke as compared to controls at 50% of MVC and (b) reduced good variability and increased bad variability components in patients with stroke at 50% of MVC...
May 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28149390/biomechanics-as-a-window-into-the-neural-control-of-movement
#14
Mark L Latash
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...
September 1, 2016: Journal of Human Kinetics
https://www.readbyqxmd.com/read/28004203/aging-effect-on-muscle-synergies-in-stepping-forth-during-a-forward-perturbation
#15
Yun Wang, Kazuhiko Watanabe, Tadayoshi Asaka
PURPOSE: We explored changes in muscle interactions during healthy aging as a window into neural control strategies of postural preparation to action/perturbation. In particular, we quantified the strength of multi-muscle synergies stabilizing the center of pressure (COP) displacement during the preparation for making a step associated with support surface translations. METHODS: Young and elderly subjects were required to make a step in response to support surface perturbations...
January 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/27999535/dynamic-determinants-of-the-uncontrolled-manifold-during-human-quiet-stance
#16
Yasuyuki Suzuki, Hiroki Morimoto, Ken Kiyono, Pietro G Morasso, Taishin Nomura
Human postural sway during stance arises from coordinated multi-joint movements. Thus, a sway trajectory represented by a time-varying postural vector in the multiple-joint-angle-space tends to be constrained to a low-dimensional subspace. It has been proposed that the subspace corresponds to a manifold defined by a kinematic constraint, such that the position of the center of mass (CoM) of the whole body is constant in time, referred to as the kinematic uncontrolled manifold (kinematic-UCM). A control strategy related to this hypothesis (CoM-control-strategy) claims that the central nervous system (CNS) aims to keep the posture close to the kinematic-UCM using a continuous feedback controller, leading to sway patterns that mostly occur within the kinematic-UCM, where no corrective control is exerted...
2016: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/27866261/anticipatory-postural-adjustments-and-anticipatory-synergy-adjustments-preparing-to-a-postural-perturbation-with-predictable-and-unpredictable-direction
#17
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...
March 2017: 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
#18
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...
February 2017: 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
#19
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...
March 2017: Journal of Motor Behavior
https://www.readbyqxmd.com/read/27628205/functional-connectivity-in-the-neuromuscular-system-underlying-bimanual-coordination
#20
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
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"