Kinematic analysis of the human wrist during pointing tasks

Campolo, Domenico; Formica, Domenico; Guglielmelli, Eugenio; Keller, Flavio

doi:10.1007/s00221-009-2073-1

Cited by 40 publications

(73 citation statements)

References 34 publications

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“…1-right, both the wrist pointing directions n i (red circles) and the rotation vectors r i (blue crosses) are represented. Our analysis confirmed previous results [6] in that the rotation vectors tend to lie on a 2-dimensional surface (Donders' law) which can be well approximated by a plane near the 'zero' position.…”

Section: Discussionsupporting

confidence: 90%

“…1) the position of a round cursor is determined, in real-time, directly by the orientation of the subject's wrist (the cursor is the projection of the pointing vector n i onto the screen plane). A more detailed description of the experimental setup can be found in [6].…”

Section: B Experimental Setupmentioning

confidence: 99%

“…In previous studies we showed that, similarly to eyes movements where Donders' law applies [10], CNS solves the redundancy of such kind of tasks by imposing a motor f.keller@unicampus.it strategy which constraints movements on 2-dimensional surfaces (called "Donders' surfaces") in the 3-D space of wrist and forearm configuration [6].…”

Section: Introductionmentioning

confidence: 99%

“…Here, we propose an experimental setup and protocol to address these issues. In particular we will assess motor learning during adaptation, analyzing the kinematics indices proposed by [11] and the motor strategies studied in [6], [12]- [13].…”

Section: Introductionmentioning

confidence: 99%

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Motor adaptation during redundant tasks with the wrist

Formica

Campolo

Taffoni

et al. 2011

2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Abstract-This study analyzes motor adaptation during a redundant tasks with the wrist. The goal is threefold: (i) understanding if motor adaptation also occurs when CNS is involved in the solution of the redundancy problem; (ii) addressing whether motor strategies used to solve redundancy (i.e Donders' law) are disrupted or not during adaptation; (iii) verifying if motor strategies remain the same during adaptation and washout or they themselves adapt. First of all, our data confirm that CNS adapts its movements to the perturbation also when it is committed in the execution of a redundant task. Secondly, we showed that motor strategies used to solve redundancy (i.e Donders' law) are not disrupted during adaptation, since absolute values of thickness during the whole protocol remain in the range of physiological values. Lastly, analysis of the curvature of Donders' surfaces suggests that motor strategies, such as Donders' law, remain invariant during motor adaptation in redundant tasks.

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Section: Discussionsupporting

confidence: 90%

Section: B Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Motor adaptation during redundant tasks with the wrist

Formica

Campolo

Taffoni

et al. 2011

2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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“…To make natural wrist rotations, the neuromuscular system must plan and/or control for the two-dimensional (2-D) stiffness encountered during the rotation. It has been suggested that wrist stiffness visibly affects the path shape of wrist rotations (Charles and Hogan 2010) and even influences pronation and supination of the forearm (Campolo et al 2010;Charles 2008). Therefore, understanding how the neuromuscular system plans and controls natural wrist rotations requires a knowledge of wrist stiffness in 2 DOF.…”

mentioning

confidence: 99%

The passive stiffness of the wrist and forearm

Formica

Charles

Zollo

et al. 2012

Journal of Neurophysiology

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108

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Because wrist rotation dynamics are dominated by stiffness (Charles SK, Hogan N. J Biomech 44: 614 -621, 2011), understanding how humans plan and execute coordinated wrist rotations requires knowledge of the stiffness characteristics of the wrist joint. In the past, the passive stiffness of the wrist joint has been measured in 1 degree of freedom (DOF). Although these 1-DOF measurements inform us of the dynamics the neuromuscular system must overcome to rotate the wrist in pure flexion-extension (FE) or pure radial-ulnar deviation (RUD), the wrist rarely rotates in pure FE or RUD. Instead, understanding natural wrist rotations requires knowledge of wrist stiffness in combinations of FE and RUD. The purpose of this report is to present measurements of passive wrist stiffness throughout the space spanned by FE and RUD. Using a rehabilitation robot designed for the wrist and forearm, we measured the passive stiffness of the wrist joint in 10 subjects in FE, RUD, and combinations. For comparison, we measured the passive stiffness of the forearm (in pronation-supination), as well. Our measurements in pure FE and RUD agreed well with previous 1-DOF measurements. We have linearized the 2-DOF stiffness measurements and present them in the form of stiffness ellipses and as stiffness matrices useful for modeling wrist rotation dynamics. We found that passive wrist stiffness was anisotropic, with greater stiffness in RUD than in FE. We also found that passive wrist stiffness did not align with the anatomical axes of the wrist; the major and minor axes of the stiffness ellipse were rotated with respect to the FE and RUD axes by ϳ20°. The direction of least stiffness was between ulnar flexion and radial extension, a direction used in many natural movements (known as the "dart-thrower's motion"), suggesting that the nervous system may take advantage of the direction of least stiffness for common wrist rotations. wrist stiffness; muscle tone; neuromuscular; motor control; spasticity GRACEFUL MOVEMENT REQUIRES that the neuromuscular system compensate for unwanted dynamics of the body. For example, it is well known that simple reaching movements require complex torques to compensate for the coupled inertial dynamics of the arm (Hollerbach and Flash 1982). Decades of research have shown that the compensation of unwanted limb dynamics is accomplished through a combination of feedback control (through muscles, reflex loops, and adaptation) and predictive control, and much effort has focused specifically on how the brain compensates for the coupled inertial dynamics of the arm during reaching movements (Bastian et al. 1996;Bastian 2006).Recent work has shown that the dynamics of wrist rotations are quite different from reaching movements: wrist rotations are dominated by stiffness, not inertia (Charles and Hogan 2011), suggesting that a major part of wrist control involves compensating for the stiffness of the wrist joint. Several studies have measured wrist stiffness in flexion and/or extension (Axelson and Hagbarth 2001;Cornu et a...

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Epistemological Foundation of Biometrics

Ghilardi

Keller

2012

The International Library of Ethics, Law and Technology

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Kinematic analysis of the human wrist during pointing tasks

Cited by 40 publications

References 34 publications

Motor adaptation during redundant tasks with the wrist

Motor adaptation during redundant tasks with the wrist

The passive stiffness of the wrist and forearm

Epistemological Foundation of Biometrics

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