| Records |
| Author |
Levin, M.F.; Liebermann, D.G.; Parmet, Y.; Berman, S. |
| Title |
Compensatory Versus Noncompensatory Shoulder Movements Used for Reaching in Stroke |
Type |
Journal Article |
| Year |
2015 |
Publication |
Neurorehabilitation and Neural Repair |
Abbreviated Journal  |
Neurorehabil Neural Repair |
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Issue |
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Pages |
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| Keywords |
adaptation; arm movement; compensation; kinematics; recovery; rehabilitation |
| Abstract |
BACKGROUND: The extent to which the upper-limb flexor synergy constrains or compensates for arm motor impairment during reaching is controversial. This synergy can be quantified with a minimal marker set describing movements of the arm-plane. OBJECTIVES: To determine whether and how (a) upper-limb flexor synergy in patients with chronic stroke contributes to reaching movements to different arm workspace locations and (b) reaching deficits can be characterized by arm-plane motion. METHODS: Sixteen post-stroke and 8 healthy control subjects made unrestrained reaching movements to targets located in ipsilateral, central, and contralateral arm workspaces. Arm-plane, arm, and trunk motion, and their temporal and spatial linkages were analyzed. RESULTS: Individuals with moderate/severe stroke used greater arm-plane movement and compensatory trunk movement compared to those with mild stroke and control subjects. Arm-plane and trunk movements were more temporally coupled in stroke compared with controls. Reaching accuracy was related to different segment and joint combinations for each target and group: arm-plane movement in controls and mild stroke subjects, and trunk and elbow movements in moderate/severe stroke subjects. Arm-plane movement increased with time since stroke and when combined with trunk rotation, discriminated between different subject groups for reaching the central and contralateral targets. Trunk movement and arm-plane angle during target reaches predicted the subject group. CONCLUSIONS: The upper-limb flexor synergy was used adaptively for reaching accuracy by patients with mild, but not moderate/severe stroke. The flexor synergy, as parameterized by the amount of arm-plane motion, can be used by clinicians to identify levels of motor recovery in patients with stroke. |
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English |
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1545-9683 |
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| Notes |
PMID:26510934 |
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no |
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Serial |
79 |
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| Author |
Biess, A.; Flash, T.; Liebermann, D.G. |
| Title |
Riemannian geometric approach to human arm dynamics, movement optimization, and invariance |
Type |
Journal Article |
| Year |
2011 |
Publication |
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics |
Abbreviated Journal |
Phys Rev E Stat Nonlin Soft Matter Phys |
| Volume |
83 |
Issue |
3 Pt 1 |
Pages |
031927 |
| Keywords |
Arm/*physiology; Biomechanics; Computer Simulation; Humans; Kinetics; Male; Models, Biological; Models, Statistical; Models, Theoretical; *Movement; Psychomotor Performance/*physiology; Range of Motion, Articular/physiology; Reaction Time/physiology; Space Perception/*physiology; Torque |
| Abstract |
We present a generally covariant formulation of human arm dynamics and optimization principles in Riemannian configuration space. We extend the one-parameter family of mean-squared-derivative (MSD) cost functionals from Euclidean to Riemannian space, and we show that they are mathematically identical to the corresponding dynamic costs when formulated in a Riemannian space equipped with the kinetic energy metric. In particular, we derive the equivalence of the minimum-jerk and minimum-torque change models in this metric space. Solutions of the one-parameter family of MSD variational problems in Riemannian space are given by (reparameterized) geodesic paths, which correspond to movements with least muscular effort. Finally, movement invariants are derived from symmetries of the Riemannian manifold. We argue that the geometrical structure imposed on the arm's configuration space may provide insights into the emerging properties of the movements generated by the motor system. |
| Address |
Bernstein Center for Computational Neuroscience, DE-37073 Gottingen, Germany. armin@nld.ds.mpg.de |
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English |
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1539-3755 |
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PMID:21517543 |
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no |
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29 |
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| Author |
Friedman, J.; Amiaz, A.; Korman, M. |
| Title |
The online and offline effects of changing movement timing variability during training on a finger-opposition task |
Type |
Journal Article |
| Year |
2022 |
Publication |
Scientific Reports |
Abbreviated Journal |
Sci Rep |
| Volume |
12 |
Issue |
1 |
Pages |
13319 |
| Keywords |
Fingers; Humans; *Learning; *Motor Skills; Movement; Psychomotor Performance; Upper Extremity |
| Abstract |
In motor learning tasks, there is mixed evidence for whether increased task-relevant variability in early learning stages leads to improved outcomes. One problem is that there may be a connection between skill level and motor variability, such that participants who initially have more variability may also perform worse on the task, so will have more room to improve. To avoid this confound, we experimentally manipulated the amount of movement timing variability (MTV) during training to test whether it improves performance. Based on previous studies showing that most of the improvement in finger-opposition tasks comes from optimizing the relative onset time of the finger movements, we used auditory cues (beeps) to guide the onset times of sequential movements during a training session, and then assessed motor performance after the intervention. Participants were assigned to three groups that either: (a) followed a prescribed random rhythm for their finger touches (Variable MTV), (b) followed a fixed rhythm (Fixed control MTV), or (c) produced the entire sequence following a single beep (Unsupervised control MTV). While the intervention was successful in increasing MTV during training for the Variable group, it did not lead to improved outcomes post-training compared to either control group, and the use of fixed timing led to significantly worse performance compared to the Unsupervised control group. These results suggest that manipulating MTV through auditory cues does not produce greater learning than unconstrained training in motor sequence tasks. |
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2045-2322 |
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PMID:35922460; PMCID:PMC9349301 |
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no |
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Serial |
115 |
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