ELECTROMYOGRAPHIC CONTROL OF MOVEMENT TIME IN A RAPID AIMING MOVEMENT

2008 ◽  
Vol 107 (6) ◽  
pp. 353 ◽  
Author(s):  
DAVlD E. SHERWOOD
Keyword(s):  
Movement Time ◽  
Aiming Movement

Electromyographic Control of Movement Time in a Rapid Aiming Movement

2008 ◽  
Vol 107 (2) ◽  
pp. 353-364
Author(s):  
David E. Sherwood
Keyword(s):  
Movement Time ◽  
Elbow Flexion ◽  
Burst Duration ◽  
Emg Activity ◽  
Emg Amplitude ◽  
Large Numbers ◽  
The Central Nervous System ◽  
Human Limb ◽  
The Right ◽  
Aiming Movement

One of the major issues to emerge from research on human-limb movement is the manner in which the central nervous system regulates electromyographic (EMG) activity to produce movements that differ in duration and distance. Different models of control predict different relations between EMC characteristics and movement kinematics, particularly with regard to the role of EMC burst duration and movement time. However, models have been evaluated with means averaged over individuals and across large numbers of practice trials. The goal of this study was to assess how well individual subjects' data conform to the predictions of the control models. Participants ( n = 4) performed an elbow flexion and extension task over 45° in movement times between 90 and 260 msec. EMG amplitude and EMG burst duration from the right elbow flexors were correlated with movement time for each individual. As expected, movement time was positively correlated with EMG burst duration and negatively correlated with EMG amplitude, with wider ranges in the EMG burst duration–movement time correlations across participants. Data from all participants supported predictions of the impulse-timing control model, but the slopes of the studied relations varied across participants.

scholarly journals Fitts' law is not continuous in reciprocal aiming

2009 ◽  
Vol 277 (1685) ◽  
pp. 1179-1184 ◽  
Author(s):  
Raoul Huys ◽  
Laure Fernandez ◽  
Reinoud J. Bootsma ◽  
Viktor K. Jirsa
Keyword(s):  
Task Difficulty ◽  
Control Mechanism ◽  
Movement Time ◽  
Control Mechanisms ◽  
Rhythmic Movements ◽  
Discrete Movements ◽  
Explicit Formulation ◽  
Fitts Law ◽  
Aiming Movement ◽  
Human Nervous System

It takes longer to accomplish difficult tasks than easy ones. In the context of motor behaviour, Fitts' famous law states that the time needed to successfully execute an aiming movement increases linearly with task difficulty. While Fitts' explicit formulation has met criticism, the relation between task difficulty and movement time is invariantly portrayed as continuous. Here, we demonstrate that Fitts' law is discontinuous in reciprocal aiming owing to a transition in operative motor control mechanisms with increasing task difficulty. In particular, rhythmic movements are implemented in easy tasks and discrete movements in difficult ones. How movement time increases with task difficulty differs in both movement types. It appears, therefore, that the human nervous system abruptly engages a different control mechanism when task difficulty increases.

Effects of Practice and Unpredictable Distractors on Planning and Executing Aiming after Stroke

2003 ◽  
Vol 17 (2) ◽  
pp. 93-100 ◽  
Author(s):  
Patricia S. Pohl ◽  
Diane L. Filion ◽  
Seok Hun Kim
Keyword(s):  
Motor Performance ◽  
Comparison Group ◽  
Movement Time ◽  
Movement Planning ◽  
Aiming Movements ◽  
Visual Distractor ◽  
Secondary Purpose ◽  
Comparison Groups ◽  
The Right ◽  
Aiming Movement

The primary purpose of this study was to examine practice effects on the planning and execution of an aiming movement after right versus left stroke. A secondary purpose was to investigate the effects of a distractor that appeared randomly on motor performance after stroke. Right-hand dominant individuals, 15 with right stroke (right-sided brain damage), 16 with left stroke, and 30 without stroke, performed aiming movements to targets. Those with stroke used the ipsilesional upper extremity (UE). Right and left comparison groups used the right and left UE, respectively. Reaction time (RT) and movement time (MT) were collected to represent movement planning and execution, respectively. Individuals with right stroke improved RT with practice. Individuals with left stroke did not improve RT with practice and made more errors than their comparison group. Those with left stroke achieved faster MT with practice, but MT remained slower than their comparison group. There were no effects of the distractor on RT or MT. Adults with left stroke have persistent deficits in movement planning and execution. Further studies are needed to determine how the performance of older adults, with or without stroke, is affected by an unpredictable visual distractor.

Movement time when circumventing obstacles in a 3-D workspace

2009 ◽  
Author(s):  
Jonathan Vaughan ◽  
Deborah Barany ◽  
Anthony Sali ◽  
Steven Jax ◽  
David A. Rosenbaum
Keyword(s):  
Movement Time

Movement time as a determiner of timing accuracy.

1969 ◽  
Vol 79 (1, Pt.1) ◽  
pp. 43-47 ◽  
Author(s):  
Richard A. Schmidt
Keyword(s):  
Movement Time ◽  
Timing Accuracy

Generality of a Speed Factor in Simple Reaction and Movement Time

1960 ◽  
Vol 11 (2) ◽  
pp. 123-128 ◽  
Author(s):  
William R. Pierson ◽  
Philip J. Rasch
Keyword(s):  
Movement Time ◽  
Simple Reaction ◽  
Speed Factor

scholarly journals Risk Analysis of Road Tunnels: A Computational Fluid Dynamic Model for Assessing the Effects of Natural Ventilation

2020 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Ciro Caliendo ◽  
Gianluca Genovese ◽  
Isidoro Russo
Keyword(s):  
Natural Ventilation ◽  
Fluid Dynamic ◽  
Movement Time ◽  
Radiant Heat ◽  
Heat Fluxes ◽  
Maximum Heat ◽  
Road Tunnels ◽  
Maximum Heat Release ◽  
Computational Fluid Dynamics Cfd ◽  
Time Required

We have developed an appropriate Computational Fluid Dynamics (CFD) model for assessing the exposure to risk of tunnel users during their evacuation process in the event of fire. The effects on escaping users, which can be caused by fire from different types of vehicles located in various longitudinal positions within a one-way tunnel with natural ventilation only and length less than 1 km are shown. Simulated fires, in terms of maximum Heat Release Rate (HRR) are: 8, 30, 50, and 100 MW for two cars, a bus, and two types of Heavy Goods Vehicles (HGVs), respectively. With reference to environmental conditions (i.e., temperatures, radiant heat fluxes, visibility distances, and CO and CO2 concentrations) along the evacuation path, the results prove that these are always within the limits acceptable for user safety. The exposure to toxic gases and heat also confirms that the tunnel users can safely evacuate. The evacuation time was found to be higher when fire was related to the bus, which is due to a major pre-movement time required for leaving the vehicle. The findings show that mechanical ventilation is not necessary in the case of the tunnel investigated. It is to be emphasized that our modeling might represent a reference in investigating the effects of natural ventilation in tunnels.

scholarly journals Effect of post-stroke spasticity on voluntary movement of the upper limb

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Hadar Lackritz ◽  
Yisrael Parmet ◽  
Silvi Frenkel-Toledo ◽  
Melanie C. Baniña ◽  
Nachum Soroker ◽  
...  
Keyword(s):  
Upper Limb ◽  
Target Location ◽  
Distance Measure ◽  
Movement Time ◽  
Motor Impairment ◽  
Reach To Grasp ◽  
Motion Patterns ◽  
Post Stroke ◽  
The Impact ◽  
Elbow Motion

Abstract Background Hemiparesis following stroke is often accompanied by spasticity. Spasticity is one factor among the multiple components of the upper motor neuron syndrome that contributes to movement impairment. However, the specific contribution of spasticity is difficult to isolate and quantify. We propose a new method of quantification and evaluation of the impact of spasticity on the quality of movement following stroke. Methods Spasticity was assessed using the Tonic Stretch Reflex Threshold (TSRT). TSRT was analyzed in relation to stochastic models of motion to quantify the deviation of the hemiparetic upper limb motion from the normal motion patterns during a reaching task. Specifically, we assessed the impact of spasticity in the elbow flexors on reaching motion patterns using two distinct measures of the ‘distance’ between pathological and normal movement, (a) the bidirectional Kullback–Liebler divergence (BKLD) and (b) Hellinger’s distance (HD). These measures differ in their sensitivity to different confounding variables. Motor impairment was assessed clinically by the Fugl-Meyer assessment scale for the upper extremity (FMA-UE). Forty-two first-event stroke patients in the subacute phase and 13 healthy controls of similar age participated in the study. Elbow motion was analyzed in the context of repeated reach-to-grasp movements towards four differently located targets. Log-BKLD and HD along with movement time, final elbow extension angle, mean elbow velocity, peak elbow velocity, and the number of velocity peaks of the elbow motion were computed. Results Upper limb kinematics in patients with lower FMA-UE scores (greater impairment) showed greater deviation from normality when the distance between impaired and normal elbow motion was analyzed either with the BKLD or HD measures. The severity of spasticity, reflected by the TSRT, was related to the distance between impaired and normal elbow motion analyzed with either distance measure. Mean elbow velocity differed between targets, however HD was not sensitive to target location. This may point at effects of spasticity on motion quality that go beyond effects on velocity. Conclusions The two methods for analyzing pathological movement post-stroke provide new options for studying the relationship between spasticity and movement quality under different spatiotemporal constraints.

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