The Effect of CAREX on muscle activation during a point-to-point reaching task

2015 ◽  
Author(s):  
Xin Jin ◽  
Viswanath Aluru ◽  
Preeti Raghavan ◽  
Sunil K. Agrawal
Keyword(s):  
Muscle Activation ◽  
Reaching Task ◽  
Point To Point

scholarly journals StartReact increases probability of muscle activity and distance in severe/moderate stroke survivors during two-dimensional reaching task

2019 ◽  
Author(s):  
Marziye Rahimi ◽  
Claire F. Honeycutt
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Stroke Survivors ◽  
Two Dimensional ◽  
Future Studies ◽  
Reaching Task ◽  
Movement Distance ◽  
Final Error ◽  
Activity Onset ◽  
Point To Point

AbstractObjectiveStartReact elicits faster, larger, and more appropriate muscle activation in stroke survivors but has been only cursorily studied to date during multi-jointed reaching. Our objective was to evaluate StartReact on unrestricted, two-dimensional point-to-point reaching tasks post-stroke.MethodData from 23 individuals with stroke was collected during point-to-point reaching. Voluntary and StartReact trials were compared between mild, severe/moderate, and the unimpaired arm.ResultsStartReact showed an increase in probability of muscle activity, larger muscle activity amplitude and faster muscle activity onset. Despite changes in muscle activity, metrics of movement (distance, final error, linear deviation) were largely the same between StartReact and Voluntary trials except in severe/moderate stroke who had larger reaching distances during StartReact.ConclusionWhile StartReact impacted many metrics of muscle activity, the most profound effect was on probability of muscle activity increasing 34% compared to Voluntary which allowed severe/moderate subjects to increase reaching distance but did not translate to decrease in final error suggesting that the additional movement was not always directed towards the appropriate target.SignificanceThese results indicate that SR has the capacity to activate paralyzed muscle in severe/moderate patients, but future studies are needed to explore the possible use of SR in the rehabilitation.

A Model of the Learning of Arm Trajectories from Spatial Deviations

1994 ◽  
Vol 6 (4) ◽  
pp. 359-376 ◽  
Author(s):  
Michael I. Jordan ◽  
Tamar Flash ◽  
Yoram Arnon
Keyword(s):  
Network Architecture ◽  
Muscle Activation ◽  
Human Subjects ◽  
Neural Network Architecture ◽  
Activation Patterns ◽  
Reaching Task ◽  
Hand Path ◽  
Muscle Activation Patterns ◽  
Point To Point ◽  
Simple Paths

Unconstrained point-to-point reaching movements performed in the horizontal plane tend to follow roughly straight hand paths with smooth, bell-shaped velocity profiles. The objective of the research reported here was to explore the hypothesis that these data reflect an underlying learning process that prefers simple paths in space. Under this hypothesis, movements are learned based only on spatial errors between the actual hand path and a desired hand path; temporally varying targets are not allowed. We designed a neural network architecture that learned to produce neural commands to a set of muscle-like actuators based only on information about spatial errors. Following repetitive executions of the reaching task, the network was able to generate point-to-point horizontal arm movements and the resulting muscle activation patterns and hand trajectories were found to be similar to those observed experimentally for human subjects. The implications of our results with respect to current theories of multijoint limb movement generation are discussed.

scholarly journals Primary motor cortex neurons classified in a postural task predict muscle activation patterns in a reaching task

2016 ◽  
Vol 115 (4) ◽  
pp. 2021-2032 ◽  
Author(s):  
Ethan A. Heming ◽  
Timothy P. Lillicrap ◽  
Mohsen Omrani ◽  
Troy M. Herter ◽  
J. Andrew Pruszynski ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Network Connectivity ◽  
Spatiotemporal Patterns ◽  
Neural Population ◽  
Activation Patterns ◽  
Reaching Task ◽  
Muscle Activation Patterns ◽  
Muscle Groups

Primary motor cortex (M1) activity correlates with many motor variables, making it difficult to demonstrate how it participates in motor control. We developed a two-stage process to separate the process of classifying the motor field of M1 neurons from the process of predicting the spatiotemporal patterns of its motor field during reaching. We tested our approach with a neural network model that controlled a two-joint arm to show the statistical relationship between network connectivity and neural activity across different motor tasks. In rhesus monkeys, M1 neurons classified by this method showed preferred reaching directions similar to their associated muscle groups. Importantly, the neural population signals predicted the spatiotemporal dynamics of their associated muscle groups, although a subgroup of atypical neurons reversed their directional preference, suggesting a selective role in antagonist control. These results highlight that M1 provides important details on the spatiotemporal patterns of muscle activity during motor skills such as reaching.

scholarly journals The Central Nervous System Does Not Minimize Energy Cost in Arm Movements

2010 ◽  
Vol 104 (6) ◽  
pp. 2985-2994 ◽  
Author(s):  
Dinant A. Kistemaker ◽  
Jeremy D. Wong ◽  
Paul L. Gribble
Keyword(s):  
Force Field ◽  
Energy Cost ◽  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Arm Movements ◽  
Dominant Factor ◽  
Minimal Energy ◽  
Null Field ◽  
Muscle Activation Patterns ◽  
Point To Point

It has been widely suggested that the many degrees of freedom of the musculoskeletal system may be exploited by the CNS to minimize energy cost. We tested this idea by having subjects making point-to-point movements while grasping a robotic manipulandum. The robot created a force field chosen such that the minimal energy hand path for reaching movements differed substantially from those observed in a null field. The results show that after extended exposure to the force field, subjects continued to move exactly as they did in the null field and thus used substantially more energy than needed. Even after practicing to move along the minimal energy path, subjects did not adapt their freely chosen hand paths to reduce energy expenditure. The results of this study indicate that for point-to-point arm movements minimization of energy cost is not a dominant factor that influences how the CNS arrives at kinematics and associated muscle activation patterns.

scholarly journals Saturated Muscle Activation Contributes to Compensatory Reaching Strategies After Stroke

2005 ◽  
Vol 94 (5) ◽  
pp. 2999-3008 ◽  
Author(s):  
Patrick H. McCrea ◽  
Janice J. Eng ◽  
Antony J. Hodgson
Keyword(s):  
Muscle Activation ◽  
Sagittal Plane ◽  
Reaching Movements ◽  
Abduction Angle ◽  
Task Completion ◽  
Shoulder Abduction ◽  
Reaching Task ◽  
Hand Motion ◽  
Control Subjects ◽  
Anterior Deltoid

The control and execution of movement could potentially be altered by the presence of stroke-induced weakness if muscles are incapable of generating sufficient power. The purpose of this study was to identify compensatory strategies during a forward (sagittal) reaching task for 20 persons with chronic stroke and 10 healthy age-matched controls. We hypothesized that the paretic anterior deltoid would be maximally activated (i.e., saturated) during a reaching task and that task completion would require activation of additional muscles, resulting in compensatory movements out of the sagittal plane. For reaching movements by control subjects, joint motion remained largely in the sagittal plane and hand trajectories were smooth and direct. Movement characteristics of the nonparetic arm of stroke subjects were similar to control subjects except for small increases in the abduction angle and the percentage that anterior deltoid was activated. In contrast, reaching movements of the paretic arm of stroke subjects were characterized by increased activation of all muscles, especially the lateral deltoid, in addition to the anterior deltoid, with resulting shoulder abduction power and segmented and indirect hand motion. For the paretic arm of stroke subjects, muscle and kinetic compensations increased with impairment severity and weaker muscles were used at a higher percentage of their available muscle activity. These results suggest that the inability to generate sufficient force with the typical agonists involved during a forward reaching task may necessitate compensatory muscle recruitment strategies to complete the task.

Experimental Observations on the Central Nervous System’s Governing Strategies on the Arm Reaching With Reduced Mobility

2012 ◽  
Author(s):  
Hyosang Moon ◽  
Nina P. Robson ◽  
Reza Langari ◽  
John J. Buchanan
Keyword(s):  
Motion Planning ◽  
Reaching Task ◽  
Dynamic Constraints ◽  
Hand Path ◽  
Minimum Jerk ◽  
Arm Reaching ◽  
Inverse Kinematics Problem ◽  
Planning Strategies ◽  
Point To Point ◽  
Reduced Mobility

For the motion planning of a point–to–point reaching task with a healthy arm, the CNS tends to plan the shortest hand path between two task points with a bell–shaped velocity profile. If any kinematic or dynamic constraints are imposed on the arm, the CNS adapts to the changes by incorporating learning mechanism into the motion planning. This paper seeks to identify the modified motion planning strategies of the CNS when the elbow joint is constrained to move. We present an experimental protocol, where subjects perform point–to–point reaching tasks with a lightweight elbow brace to restrict the joint kinematics with a minimal effect on the arm dynamics. From the experimental observations, the human strategies on each aspect of motion planning (i.e. hand path geometry, speed of the motion, and the arm posture selection) are hypothesized. The hypothesized strategies are developed as models and compared with the experimental data. As a result, we found that the hand path follows the rhumb line on the constraint workspace while the speed profile preserves a bell–shape, which can be roughly approximated by the minimum jerk model. In addition, by comparing the joint contributions data with and without the elbow constraint, it is hypothesized that the CNS resolves the redundancy of the inverse kinematics problem by reducing the kinetic energy of the limbs.

scholarly journals Effect of Visuomotor Colocation on 3D Fitts' Task Performance in Physical and Virtual Environments

2012 ◽  
Vol 21 (3) ◽  
pp. 305-320 ◽  
Author(s):  
Michael J. Fu ◽  
Andrew D. Hershberger ◽  
Kumiko Sano ◽  
M. Cenk Çavuşoğlu
Keyword(s):  
Virtual Environments ◽  
Task Performance ◽  
Performance Measures ◽  
Human Performance ◽  
Peak Velocity ◽  
Local Maximum ◽  
Reaching Task ◽  
Movement Error ◽  
Point To Point ◽  
Initial Movement

Given the ease that humans have with using a keyboard and mouse in typical, non-colocated computer interaction, many studies have investigated the value of colocating the visual field and motor workspaces using immersive display modalities. Significant understanding has been gained by previous work comparing physical tasks against virtual tasks, visuomotor colocation versus non-colocation, and even visuomotor rotational misalignments in virtual environments (VEs). However, few studies have explored all of these paradigms in context with each other, and it is difficult to perform interstudy comparisons because of the variation in tested motor tasks. Therefore, using a stereoscopic fish tank display setup, the goal for the current study was to characterize human performance of a 3D Fitts' point-to-point reaching task using a stylus-based haptic interface in the physical, colocated/non-colocated, and rotated VE visualization conditions. Five performance measures—throughput, efficiency, initial movement error, corrective movements, and peak velocity—were measured and used to evaluate task performance. These measures were studied in 22 subjects (11 male, 11 female, ages 20–32) performing a 3D variant of Fitts' serial task under 10 task conditions: physical, colocated VE, non-colocated VE, and rotated VEs from 45—315° in 45° increments. Hypotheses: All performance measures in the colocated VE were expected to reflect significantly reduced task performance over the real condition, but also reflect increased performance over the non-colocated VE condition. For rotational misalignments, all performance measures were expected to reflect the highest performance at 0°, reduce to the lowest performance at 90°, and rise again to a local maximum at 180° (symmetric about 0°). Results: All performance measures showed that the colocated VE condition resulted in significantly lower task performance than the physical condition and higher mean performance than the non-colocated VE condition, but the difference was not statistically significant. Also, rotation misalignments showed that task performance was mostly reduced to a minimum at 90°, 135°, and 225°. We conclude that colocated VEs may not significantly improve point-to-point reaching performance over non-colocated VEs. Also, visual rotations of ±45° affected throughput, efficiency, peak velocity, and initial movement error, but the number of corrective movements were not affected until ± 90°.

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