scholarly journals Enhanced crosslimb transfer of force-field learning for dynamics that are identical in extrinsic and joint-based coordinates for both limbs

2016 ◽  
Vol 115 (1) ◽  
pp. 445-456 ◽  
Author(s):  
Timothy J. Carroll ◽  
Aymar de Rugy ◽  
Ian S. Howard ◽  
James N. Ingram ◽  
Daniel M. Wolpert
Keyword(s):  
Force Field ◽  
Mirror Symmetry ◽  
Sagittal Plane ◽  
Transverse Plane ◽  
Field Perturbation ◽  
Neural Representations ◽  
Initial Learning ◽  
The Right ◽  
Opposite Limb ◽  
Sensorimotor Representations

Humans are able to adapt their motor commands to make accurate movements in novel sensorimotor environments, such as when wielding tools that alter limb dynamics. However, it is unclear to what extent sensorimotor representations, obtained through experience with one limb, are available to the opposite, untrained limb and in which form they are available. Here, we compared crosslimb transfer of force-field compensation after participants adapted to a velocity-dependent curl field, oriented either in the sagittal or the transverse plane. Due to the mirror symmetry of the limbs, the force field had identical effects for both limbs in joint and extrinsic coordinates in the sagittal plane but conflicting joint-based effects in the transverse plane. The degree of force-field compensation exhibited by the opposite arm in probe trials immediately after initial learning was significantly greater after sagittal (26 ± 5%) than transverse plane adaptation (9 ± 4%; P < 0.001), irrespective of whether participants learned initially with the left or the right arm or via abrupt or gradual exposure to the force field. Thus transfer was impaired when the orientation of imposed dynamics conflicted in intrinsic coordinates for the two limbs. The data reveal that neural representations of novel dynamics are only partially available to the opposite limb, since transfer is incomplete even when force-field perturbation is spatially compatible for the two limbs, according to both intrinsic and extrinsic coordinates.

scholarly journals The effect of prosthetic torsional stiffness on the golf swing kinematics of a left and a right-sided trans-tibial amputee

2004 ◽  
Vol 28 (2) ◽  
pp. 121-131 ◽  
Author(s):  
J. P. Rogers ◽  
S. C. Strike ◽  
E. S. Wallace
Keyword(s):  
Ankle Joint ◽  
Perceived Stress ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Transverse Plane ◽  
Golf Swing ◽  
Torsional Stiffness ◽  
The Difference ◽  
The Right ◽  
Socket Interface

The golf swing is a biomechanically complex movement requiring three-dimensional movements at the ankle joint complex (AJC), the hips and shoulders. Trans-tibial amputees lose the natural AJC movements as many prostheses do not allow three dimensional foot movements. Torsion devices have been developed and incorporated into prostheses to facilitate internal and external transverse plane rotations. These devices can help amputees to compensate for the loss of movement and to reduce shearing stresses at the stump-socket interface. The primary aim of the present study was to investigate the effects of three torsion devices on body rotations during the golf swing. Two trans-tibial amputees (one right-sided and one left-sided) were analysed using three-dimensional video analysis at address (ADR), the top of the backswing (TBS) and at the end of the follow-through (EFT). The participants played shots with a 3-wood under three different prosthetic conditions (two with a torsion device set to different stiffness values, and one with no torsion device). The results showed that the torsion device served to improve the hip and shoulder rotations of the left-side amputee without increasing perceived stress at the stump. The torsion device had minimal effect on the hip and shoulder rotations of the right-side amputee, although perceived stress was reduced. The difference in results between the right-sided and left-sided amputees was due to the different requirements of each foot during the golf swing. The main problem faced by the right-side amputee was a loss of the sagittal plane movement of ankle joint plantarflexion at EFT, rather than the transverse plane movement.

scholarly journals Separate representations of dynamics in rhythmic and discrete movements: evidence from motor learning

2011 ◽  
Vol 105 (4) ◽  
pp. 1722-1731 ◽  
Author(s):  
Ian S. Howard ◽  
James N. Ingram ◽  
Daniel M. Wolpert
Keyword(s):  
Motor Learning ◽  
Force Field ◽  
Motor System ◽  
Neural Mechanisms ◽  
Control Mechanisms ◽  
Discrete Movements ◽  
Field Perturbation ◽  
Movement Path ◽  
Neural Representations ◽  
Separate Control

Rhythmic and discrete arm movements occur ubiquitously in everyday life, and there is a debate as to whether these two classes of movements arise from the same or different underlying neural mechanisms. Here we examine interference in a motor-learning paradigm to test whether rhythmic and discrete movements employ at least partially separate neural representations. Subjects were required to make circular movements of their right hand while they were exposed to a velocity-dependent force field that perturbed the circularity of the movement path. The direction of the force-field perturbation reversed at the end of each block of 20 revolutions. When subjects made only rhythmic or only discrete circular movements, interference was observed when switching between the two opposing force fields. However, when subjects alternated between blocks of rhythmic and discrete movements, such that each was uniquely associated with one of the perturbation directions, interference was significantly reduced. Only in this case did subjects learn to corepresent the two opposing perturbations, suggesting that different neural resources were employed for the two movement types. Our results provide further evidence that rhythmic and discrete movements employ at least partially separate control mechanisms in the motor system.

scholarly journals Neural alignment predicts learning outcomes in students taking an introduction to computer science course

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Meir Meshulam ◽  
Liat Hasenfratz ◽  
Hanna Hillman ◽  
Yun-Fei Liu ◽  
Mai Nguyen ◽  
...  
Keyword(s):  
Computer Science ◽  
Learning Outcomes ◽  
Brain Activity ◽  
Activity Patterns ◽  
Real Life ◽  
Final Exam ◽  
Neural Representations ◽  
Real Life Setting ◽  
The Right ◽  
Mri Study

AbstractDespite major advances in measuring human brain activity during and after educational experiences, it is unclear how learners internalize new content, especially in real-life and online settings. In this work, we introduce a neural approach to predicting and assessing learning outcomes in a real-life setting. Our approach hinges on the idea that successful learning involves forming the right set of neural representations, which are captured in canonical activity patterns shared across individuals. Specifically, we hypothesized that learning is mirrored in neural alignment: the degree to which an individual learner’s neural representations match those of experts, as well as those of other learners. We tested this hypothesis in a longitudinal functional MRI study that regularly scanned college students enrolled in an introduction to computer science course. We additionally scanned graduate student experts in computer science. We show that alignment among students successfully predicts overall performance in a final exam. Furthermore, within individual students, we find better learning outcomes for concepts that evoke better alignment with experts and with other students, revealing neural patterns associated with specific learned concepts in individuals.

scholarly journals IMU-Based Effects Assessment of the Use of Foot Orthoses in the Stance Phase during Running and Asymmetry between Extremities

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3277
Author(s):  
Juan Luis Florenciano Restoy ◽  
Jordi Solé-Casals ◽  
Xantal Borràs-Boix
Keyword(s):  
Contact Time ◽  
Stance Phase ◽  
Inertial Sensors ◽  
Sagittal Plane ◽  
Plantar Flexion ◽  
Foot Orthoses ◽  
Foot Kinematics ◽  
Running Injuries ◽  
The Right ◽  
Movement Differences

The objectives of this study were to determine the amplitude of movement differences and asymmetries between feet during the stance phase and to evaluate the effects of foot orthoses (FOs) on foot kinematics in the stance phase during running. In total, 40 males were recruited (age: 43.0 ± 13.8 years, weight: 72.0 ± 5.5 kg, height: 175.5 ± 7.0 cm). Participants ran on a running treadmill at 2.5 m/s using their own footwear, with and without the FOs. Two inertial sensors fixed on the instep of each of the participant’s footwear were used. Amplitude of movement along each axis, contact time and number of steps were considered in the analysis. The results indicate that the movement in the sagittal plane is symmetric, but that it is not in the frontal and transverse planes. The right foot displayed more degrees of movement amplitude than the left foot although these differences are only significant in the abduction case. When FOs are used, a decrease in amplitude of movement in the three axes is observed, except for the dorsi-plantar flexion in the left foot and both feet combined. The contact time and the total step time show a significant increase when FOs are used, but the number of steps is not altered, suggesting that FOs do not interfere in running technique. The reduction in the amplitude of movement would indicate that FOs could be used as a preventive tool. The FOs do not influence the asymmetry of the amplitude of movement observed between feet, and this risk factor is maintained. IMU devices are useful tools to detect risk factors related to running injuries. With its use, even more personalized FOs could be manufactured.

Sensitivity of Intersegmental Angles of the Spinal Column to Errors Due to Marker Misplacement

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Hossein Rouhani ◽  
Sara Mahallati ◽  
Richard Preuss ◽  
Kei Masani ◽  
Milos R. Popovic
Keyword(s):  
Relative Error ◽  
Sagittal Plane ◽  
Gaussian Function ◽  
Spinal Column ◽  
Transverse Plane ◽  
Lumbar Region ◽  
Experimental Errors ◽  
Rms Error ◽  
Lower Lumbar ◽  
Anterior Direction

The ranges of angular motion measured using multisegmented spinal column models are typically small, meaning that minor experimental errors can potentially affect the reliability of these measures. This study aimed to investigate the sensitivity of the 3D intersegmental angles, measured using a multisegmented spinal column model, to errors due to marker misplacement. Eleven healthy subjects performed trunk bending in five directions. Six cameras recorded the trajectory of 22 markers, representing seven spinal column segments. Misplacement error for each marker was modeled as a Gaussian function with a standard deviation of 6 mm, and constrained to a maximum value of 12 mm in each coordinate across the skin. The sensitivity of 3D intersegmental angles to these marker misplacement errors, added to the measured data, was evaluated. The errors in sagittal plane motions resulting from marker misplacement were small (RMS error less than 3.2 deg and relative error in the angular range less than 15%) during the five trunk bending direction. The errors in the frontal and transverse plane motions, induced by marker misplacement, however, were large (RMS error up to 10.2 deg and relative error in the range up to 58%), especially during trunk bending in anterior, anterior-left, and anterior-right directions, and were often comparable in size to the intersubject variability for those motions. The induced errors in the frontal and transverse plane motions tended to be the greatest at the intersegmental levels in the lower lumbar region. These observations questioned reliability of angle measures in the frontal and transverse planes particularly in the lower lumbar region during trunk bending in anterior direction, and thus did not recommend interpreting these measures for clinical evaluation and decision-making.

scholarly journals Reversal of Bimanual Feedback Responses With Changes in Task Goal

2009 ◽  
Vol 101 (1) ◽  
pp. 283-288 ◽  
Author(s):  
Jörn Diedrichsen ◽  
Samantha Gush
Keyword(s):  
Force Field ◽  
Covariance Structure ◽  
Direct Interaction ◽  
Virtual Object ◽  
Upward Movement ◽  
Finish Line ◽  
Task Goal ◽  
The Right ◽  
Task Goals ◽  
Feedback Responses

We show that fast bimanual coordinative feedback responses can be reversed with changes in task goals. Participants moved a flexible virtual object across a finish line with an upward movement of both hands. In one condition, the middle of the object had to be aligned with a spatial goal at the end of the movement. In the second condition, the object had to be kept at a specific length. During the movement, a velocity-dependent force field was applied randomly to one of the hands to the left or to the right. Depending on the task condition, the unperturbed hand showed fast feedback corrections, either in or against the direction of the force field on the other hand. In the object-length condition we found evidence for a mixture of task goals: early in the movement the correction of the unperturbed hand was aimed at stabilizing object length; later in the movement, the correction reversed direction to reach a symmetric body posture in the end of the movement. The observed differences in feedback responses between task conditions also influenced the covariance structure of unperturbed movements and the adaptation when a specific force field was applied repeatedly to one of the hands. The results are congruent with the notion that coordination is established flexibly through a representation of the task-relevant controlled variables, rather than through a direct interaction between motor commands.

scholarly journals A Novel Technique to Assess Rotational Deformities in Lower Extremities

2020 ◽  
Author(s):  
Peyman Bakhshayesh ◽  
Ugwunna Ihediwa ◽  
Sukha Sandher ◽  
Alexandros Vris ◽  
Nima Heidari ◽  
...  
Keyword(s):  
Moving Objects ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Contralateral Side ◽  
Ct Images ◽  
New Technique ◽  
X Rays ◽  
Digital Technique ◽  
The Right ◽  
Im Nailing

Abstract Introduction: Rotational deformities following IM nailing of tibia has a reported incidence of as high as 20%. Common techniques to measure deformities following IM nailing of tibia are either based on clinical assessment, plain X-rays or CT-scan comparing the treated leg with the uninjured contralateral side. All these techniques are based on examiners manual calculation inherently subject to bias. Following our previous rigorous motion analysis and symmetry studies on hemi pelvises, femurs and orthopaedic implants, we aimed to introduce a novel fully digital technique to measure rotational deformities in the lower legs.Material and Methods: Following formal institutional approval from the Imperial College, CT images of 10 pairs of human lower legs were retrieved. Images were anonymized and uploaded to a research server. Three dimensional CT images of the lower legs were bilaterally reconstructed. The mirrored images of the left side were merged with the right side proximally as stationary and distally as moving objects. Discrepancies in translation and rotation were automatically calculated.Results: Our study population had a mean age of 54 ± 20 years. There were six males and four females. We observed a greater variation in translation (mm) of Centre of Mass (COM) in sagittal plane (CI: -2.959--.292) which was also presented as rotational difference alongside the antero-posterior direction or Y axis (CI: .370-1.035). In other word the right lower legs in our study were more likely to be in varus compared to the left side. However, there were no statistically significant differences in coronal or axial planes.Conclusion: Using our proposed fully digital technique we found that lower legs of the human adults were symmetrical in axial and coronal plane. We found sagittal plane differences which need further addressing in future using bigger sample size. Our novel recommended technique is fully digital and commercially available. This new technique can be useful in clinical practice addressing rotational deformities following orthopaedic surgical intervention. This new technique can substitute the previously introduced techniques.

scholarly journals Motor learning in reaching tasks leads to homogenization of task space error distribution

2021 ◽  
Author(s):  
Puneet Singh ◽  
Oishee Ghosal ◽  
Aditya Murthy ◽  
Ashitava Ghodal
Keyword(s):  
Motor Learning ◽  
Force Field ◽  
Error Distribution ◽  
Task Space ◽  
Field Perturbation ◽  
Directional Dependence ◽  
Reaching Tasks ◽  
Space Error ◽  
Human Arm ◽  
Point To Point

A human arm, up to the wrist, is often modelled as a redundant 7 degree-of-freedom serial robot. Despite its inherent nonlinearity, we can perform point-to-point reaching tasks reasonably fast and with reasonable accuracy in the presence of external disturbances and noise. In this work, we take a closer look at the task space error during point-to-point reaching tasks and learning during an external force-field perturbation. From experiments and quantitative data, we confirm a directional dependence of the peak task space error with certain directions showing larger errors than others at the start of a force-field perturbation, and the larger errors are reduced with repeated trials implying learning. The analysis of the experimental data further shows that a) the distribution of the peak error is made more uniform across directions with trials and the error magnitude and distribution approaches the value when no perturbation is applied, b) the redundancy present in the human arm is used more in the direction of the larger error, and c) homogenization of the error distribution is not seen when the reaching task is performed with the non-dominant hand. The results support the hypothesis that not only magnitude of task space error, but the directional dependence is reduced during motor learning and the workspace is homogenized possibly to increase the control efficiency and accuracy in point-to-point reaching tasks. The results also imply that redundancy in the arm is used to homogenize the workspace, and additionally since the bio-mechanically similar dominant and non-dominant arms show different behaviours, the homogenizing is actively done in the central nervous system.

scholarly journals Mirror symmetry of higher order aberrations between right and left eyes

2014 ◽  
Vol 73 (1) ◽  
Author(s):  
M. Oberholzer ◽  
W.D.H. Gillan ◽  
A. Rubin
Keyword(s):  
Wave Front ◽  
South African ◽  
Visual Function ◽  
Mirror Symmetry ◽  
Correlation Coefficients ◽  
Higher Order ◽  
Pearson Product Moment Correlation ◽  
Scatter Plots ◽  
The Right ◽  
High Order Aberrations

Introduction: There is evidence that certain measures of visual function show some type of relationship between right and left eyes in the same individual.  Similarly, particular ocular maladies may be related, or be symmetric, in the right and left eyes of the same person. There is also evidence to suggest that certain relationships do not exist between eyes in an individual. For example, diseases such as glaucoma are often asymmetric in their progression in the two eyes of an afflicted individual. Inter-ocular mirror symmetry between right and left eyes, when considering ocular wave-front aberrations (WAs), has been shown to exist by some authors. This study investigates whether mirror symmetry of high order aberrations (HOAs) exists between the right and left eyes in a cohort of South African subjects. Method: Third to 5th order Zernike coefficients (HOAs) were measured on both eyes of 66 subjects (132 eyes) using a Zywave aberrometer. A total of 15 Zernike coefficients for each eye were obtained. Mirror symmetry was investigated using correlation coefficients between the various measurements obtained from each eye. Results: Pearson product-moment correlation coefficients provide evidence that the majority of the 15 Zernike coefficients suggest the presence of mirror symmetry between right and left eyes of the 66 subjects. Examples of individual scatter plots comparing right and left eyes are presented.  Conclusion: The results of this study suggest that mirror symmetry exists in the HOAs obtained from the 132 eyes measured and thus care should be exercised when combining eyes of individuals for analysis. (S Afr Optom 2013 73(1) 39-44)

Dynamics of Within-, Inter-, and Cross-Modal Attentional Modulation

2011 ◽  
Vol 105 (2) ◽  
pp. 674-686 ◽  
Author(s):  
Tetsuo Kida ◽  
Koji Inui ◽  
Emi Tanaka ◽  
Ryusuke Kakigi
Keyword(s):  
Spatial Attention ◽  
Interstimulus Interval ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
The Other ◽  
Neural Representations ◽  
Tactile Stimuli ◽  
Sensory Modalities ◽  
The Right ◽  
Directing Attention

Numerous studies have demonstrated effects of spatial attention within single sensory modalities (within-modal spatial attention) and the effect of directing attention to one sense compared with the other senses (intermodal attention) on cortical neuronal activity. Furthermore, recent studies have been revealing that the effects of spatial attention directed to a certain location in a certain sense spread to the other senses at the same location in space (cross-modal spatial attention). The present study used magnetoencephalography to examine the temporal dynamics of the effects of within-modal and cross-modal spatial and intermodal attention on cortical processes responsive to visual stimuli. Visual or tactile stimuli were randomly presented on the left or right side at a random interstimulus interval and subjects directed attention to the left or right when vision or touch was a task-relevant modality. Sensor-space analysis showed that a response around the occipitotemporal region at around 150 ms after visual stimulation was significantly enhanced by within-modal, cross-modal spatial, and intermodal attention. A later response over the right frontal region at around 200 ms was enhanced by within-modal spatial and intermodal attention, but not by cross-modal spatial attention. These effects were estimated to originate from the occipitotemporal and lateral frontal areas, respectively. Thus the results suggest different spatiotemporal dynamics of neural representations of cross-modal attention and intermodal or within-modal attention.

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