Nondominant Arm Advantages in Load Compensation During Rapid Elbow Joint Movements

2003 ◽  
Vol 90 (3) ◽  
pp. 1503-1513 ◽  
Author(s):  
Leia B. Bagesteiro ◽  
Robert L. Sainburg
Keyword(s):  
Muscle Activity ◽  
Considerable Increase ◽  
Feedforward Control ◽  
Elbow Flexion ◽  
Control Mechanisms ◽  
Final Position ◽  
Flexor Muscle ◽  
Load Compensation ◽  
Air Jet

This study was designed to examine interlimb asymmetries in responding to unpredictable changes in inertial loads, which have implications for our understanding of the neural mechanisms underlying handedness. Subjects made repetitive single joint speed constrained 20° elbow flexion movements, while the arm was supported on a horizontal, frictionless, air-jet system. On random trials, a 2-kg mass was attached to the arm splint prior to the “go” signal. Subjects were not given explicit information about the mass prior to movement nor were they able to view their limb or the mass. Accordingly, muscle activity, recorded prior to peak tangential finger acceleration, was the same for loaded and baseline trials. After this point, substantial changes in muscle activity occurred. In both limbs, the load compensation response was associated with a reduction in extensor muscle activity, resulting in a prolonged flexion phase of motion. For the nondominant arm, this resulted in effective load compensation, such that no differences in final position accuracy occurred between loaded and baseline trials. However, the dominant arm response also included a considerable increase in flexor muscle activity. This substantially prolonged the flexor acceleration phase of motion, relative to that of the nondominant arm. As a result, the dominant arm overcompensated the effects of the load, producing a large and systematic overshoot of final position. These results indicate more effective load compensation responses for the nondominant arm; supporting a specialized role of the nondominant arm/hemisphere system in sensory feedback mediated error correction mechanisms. The results also suggest that specialization of the dominant arm system for controlling limb and task dynamics is specifically related to feedforward control mechanisms.

Learning Transfer from Flexion to Extension Movements: Importance of the Final Position

Motor Control ◽  
1998 ◽  
Vol 2 (3) ◽  
pp. 221-227 ◽  
Author(s):  
Dusko B. Ilic ◽  
Dragan M. Mirkov ◽  
Slobodan Jaric
Keyword(s):  
Elbow Flexion ◽  
Control Group ◽  
Final Position ◽  
Variable Error ◽  
Before And After ◽  
Movement Distance ◽  
Level Of Significance ◽  
Experimental Group ◽  
Flexion And Extension

Nine subjects (experimental group) were tested on rapid elbow flexion and extension movements performed in the same final position, before and after extensive practice of the movements. Nine additional subjects (control group) were also tested, but without any practice between the tests. Comparison of the pretest and posttest results suggested that the experimental group decreased their variable error (i.e., standard deviation of the final movement position) in both practiced (elbow flexion) and nonpracticed (elbow extension) movements. The control group, however, did not improve in either of tested movements. The experimental group demonstrated lower variable error in the nonpracticed elbow extensions than the control group, while the same difference for practiced elbow flexion movements was slightly below the level of significance. The results support the importance of the final position in programming of rapid, self-terminated movements; however, they do not rule out the role of other kinetic and kinematic variables (such as movement distance).

scholarly journals Tuning of feedforward control enables stable muscle force-length dynamics after loss of autogenic proprioceptive feedback

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Joanne C Gordon ◽  
Natalie C Holt ◽  
Andrew Biewener ◽  
Monica A Daley
Keyword(s):  
Steady State ◽  
Feedforward Control ◽  
Control Mechanisms ◽  
Leg Muscles ◽  
Similar Work ◽  
Numida Meleagris ◽  
Muscle Dynamics ◽  
Intact Muscle

Animals must integrate feedforward, feedback and intrinsic mechanical control mechanisms to maintain stable locomotion. Recent studies of guinea fowl (Numida meleagris) revealed that the distal leg muscles rapidly modulate force and work output to minimize perturbations in uneven terrain. Here we probe the role of reflexes in the rapid perturbation responses of muscle by studying the effects of proprioceptive loss. We induced bilateral loss of autogenic proprioception in the lateral gastrocnemius muscle (LG) using self-reinnervation. We compared in vivo muscle dynamics and ankle kinematics in birds with reinnervated and intact LG. Reinnervated and intact LG exhibit similar steady state mechanical function and similar work modulation in response to obstacle encounters. Reinnervated LG exhibits 23ms earlier steady-state activation, consistent with feedforward tuning of activation phase to compensate for lost proprioception. Modulation of activity duration is impaired in rLG, confirming the role of reflex feedback in regulating force duration in intact muscle.

scholarly journals Tuning of feedforward control enables stable muscle force-length dynamics after loss of autogenic proprioceptive feedback

2019 ◽  
Author(s):  
JC Gordon ◽  
NC Holt ◽  
AA Biewener ◽  
MA Daley
Keyword(s):  
Feedforward Control ◽  
Control Mechanisms ◽  
Uneven Terrain ◽  
Leg Muscles ◽  
Numida Meleagris ◽  
Muscle Dynamics ◽  
Ankle Kinematics ◽  
Intact Muscle

AbstractAnimals must integrate feedforward, feedback and intrinsic mechanical control mechanisms to maintain stable locomotion. Recent studies of guinea fowl (Numida meleagris) revealed that the distal leg muscles rapidly modulate force and work output to minimize perturbations in uneven terrain. Here we probe the role of reflexes in the rapid perturbation response of muscle by studying the effects of proprioceptive loss. We induced bilateral loss of autogenic proprioception in the lateral gastrocnemius muscle (LG) using self-reinnervation. We compared ankle kinematics and in vivo muscle dynamics in birds with reinnervated LG and intact LG. Reinnervated and intact muscles exhibit similar force-length dynamics, with rapid changes in work to stabilize running obstacle terrain. Reinnervated LG exhibits 23ms earlier steady-state activation, consistent with feedforward tuning of activation phase to compensate for lost proprioception. Modulation of force duration is impaired in rLG, confirming the role of reflex feedback in regulating force duration in intact muscle.

scholarly journals Using Regulatory Flexibility to Address Market Informality in Seed Systems: A Global Study

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 377
Author(s):  
Katrin Kuhlmann ◽  
Bhramar Dey
Keyword(s):  
Seed Quality ◽  
Regulatory Environment ◽  
Control Mechanisms ◽  
Seed Systems ◽  
High Quality ◽  
Design And Implementation ◽  
Key Dimensions ◽  
Regulatory Flexibility

Seed rules and regulations determine who can produce and sell seeds, which varieties will be available in the market, the quality of seed for sale, and where seed can be bought and sold. The legal and regulatory environment for seed impacts all stakeholders, including those in the informal sector, through shaping who can participate in the market and the quality and diversity of seed available. This paper addresses a gap in the current literature regarding the role of law and regulation in linking the informal and formal seed sectors and creating more inclusive and better governed seed systems. Drawing upon insights from the literature, global case studies, key expert consultations, and a methodology on the design and implementation of law and regulation, we present a framework that evaluates how regulatory flexibility can be built into seed systems to address farmers’ needs and engage stakeholders of all sizes. Our study focuses on two key dimensions: extending market frontiers and liberalizing seed quality control mechanisms. We find that flexible regulatory approaches and practices play a central role in building bridges between formal and informal seed systems, guaranteeing quality seed in the market, and encouraging market entry for high-quality traditional and farmer-preferred varieties.

Compensation Control Mechanisms in the American States

1989 ◽  
Vol 18 (3) ◽  
pp. 325-338 ◽  
Author(s):  
Wendell C. Lawther ◽  
Earle C. Traynham ◽  
Kenneth M. Jennings
Keyword(s):  
Collective Bargaining ◽  
State Government ◽  
Control Mechanisms ◽  
Compensation Control ◽  
Initial Analysis ◽  
Personnel Practices ◽  
State Compensation ◽  
American States

There are few studies which report on the personnel practices in the American states. A survey of state compensation analysts in the Summer of 1987 elicited information concerning the use of compensation controls in state government. Results indicate that with the exception of wage and salary surveys, data concerning compensation controls is rarely collected. Initial analysis indicates that the role of the legislature and the existence of collective bargaining may have an impact on the number of controls used.

Role of Muscle Activity in Nerve-Muscle Interaction in vitro

Nature ◽  
1974 ◽  
Vol 248 (5443) ◽  
pp. 70-71 ◽  
Author(s):  
J. H. STEINBACH
Keyword(s):  
Muscle Activity ◽  
Nerve Muscle

The Main Sequence of Human Optokinetic Afternystagmus (OKAN)

2009 ◽  
Vol 101 (6) ◽  
pp. 2889-2897 ◽  
Author(s):  
Andre Kaminiarz ◽  
Kerstin Königs ◽  
Frank Bremmer
Keyword(s):  
Neural Networks ◽  
Eye Movements ◽  
Main Sequence ◽  
Critical Role ◽  
Saccade Target ◽  
Control Mechanisms ◽  
Visually Guided ◽  
Background Characteristics ◽  
Optokinetic Afternystagmus

Different types of fast eye movements, including saccades and fast phases of optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN), are coded by only partially overlapping neural networks. This is a likely cause for the differences that have been reported for the dynamic parameters of fast eye movements. The dependence of two of these parameters—peak velocity and duration—on saccadic amplitude has been termed “main sequence.” The main sequence of OKAN fast phases has not yet been analyzed. These eye movements are unique in that they are generated by purely subcortical control mechanisms and that they occur in complete darkness. In this study, we recorded fast phases of OKAN and OKN as well as visually guided and spontaneous saccades under identical background conditions because background characteristics have been reported to influence the main sequence of saccades. Our data clearly show that fast phases of OKAN and OKN differ with respect to their main sequence. OKAN fast phases were characterized by their lower peak velocities and longer durations compared with those of OKN fast phases. Furthermore we found that the main sequence of spontaneous saccades depends heavily on background characteristics, with saccades in darkness being slower and lasting longer. On the contrary, the main sequence of visually guided saccades depended on background characteristics only very slightly. This implies that the existence of a visual saccade target largely cancels out the effect of background luminance. Our data underline the critical role of environmental conditions (light vs. darkness), behavioral tasks (e.g., spontaneous vs. visually guided), and the underlying neural networks for the exact spatiotemporal characteristics of fast eye movements.

Abstract 207: Unc-51-like Kinase 1 (ULK1) Plays A Crucial Role In Mitophagy In Cardiomyocytes

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Toshiro Saito ◽  
Junichi Sadoshima
Keyword(s):  
Glucose Deprivation ◽  
High Ratio ◽  
Control Mechanisms ◽  
Oxygen Species ◽  
Predominant Role ◽  
Mitochondrial Quality Control ◽  
Over Expression ◽  
Pathological Conditions

The mitochondrion is an essential organelle that supplies ATP in cardiomyocytes (CMs). However, damaged mitochondria are harmful via the production of reactive oxygen species and induction of apoptosis in pathological conditions. Therefore, quality of mitochondria should be controlled tightly through various mitochondrial quality control mechanisms. Mitochondrial autophagy (mitophagy) is considered an integral part of this mechanism, and recent investigations uncovered the role of PINK1 and Parkin in mitophagy. However, these observations were made under artificial conditions, such as over-expression of Parkin or treatment with CCCP, and thus the precise mechanism has not been fully elucidated in more pathophysiologically relevant conditions. Recent evidence suggests that mitophagy can take place independently of ATG7, a molecule essential for the conventional form of autophagy, and that this form of autophagy is ULK1-dependent. We investigated the role of ULK1 and ATG7 in mediating mitophagy using mitochondria-targeted Keima (Mito-Keima) in cultured rat neonatal CMs. Keima has a bimodal excitation spectrum peaking at 440 and 560 nm, corresponding to the neutral and acidic pH, respectively. In CMs transfected with Mito-Keima, the fluorescent dots with a high 560nm/440nm ratio represent the mitochondria incorporated into autolysosomes which indicate mitophagy. Here we report that ULK1 plays a more predominant role in glucose deprivation (GD) -induced mitophagy than ATG7. Control CMs exhibited 8.7±1.0 % of the area of high-ratio dots per cells after GD. Knockdown of ULK1 significantly reduced the area to 2.3±0.9 % in CMs after GD (p<0.01, vs sh-Control). The reduction was significantly greater in CMs with knockdown of ULK1 than that of ATG7 (7.0±1.6 %, p<0.05, sh-ULK1 vs sh-ATG7). In addition, knockdown of Beclin1 and Drp1 also significantly decreased the area of high-ratio dots (about 1.0 % and 0.5 %, respectively). Overexpression of ULK1 was sufficient to induce mitophagy without starvation, whereas that of ATG7 was not. These results suggest that ULK1, Beclin1 and Drp1 play an essential role in mediating GD-induced mitophagy in CMs.

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