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Author |
Lowenthal-Raz, J.; Liebermann, D.G.; Friedman, J.; Soroker, N. |
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Title |
Kinematic descriptors of arm reaching movement are sensitive to hemisphere-specific immediate neuromodulatory effects of transcranial direct current stimulation post stroke |
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Journal Article |
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Year |
2024 |
Publication |
Scientific Reports |
Abbreviated Journal |
Sci Rep |
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Volume |
14 |
Issue |
1 |
Pages |
11971 |
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Keywords |
Humans; *Transcranial Direct Current Stimulation/methods; Male; Female; Middle Aged; *Stroke/physiopathology/therapy; Biomechanical Phenomena; Aged; *Arm/physiopathology; *Movement/physiology; *Stroke Rehabilitation/methods; Single-Blind Method; Cross-Over Studies |
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Abstract |
Transcranial direct current stimulation (tDCS) exerts beneficial effects on motor recovery after stroke, presumably by enhancement of adaptive neural plasticity. However, patients with extensive damage may experience null or deleterious effects with the predominant application mode of anodal (excitatory) stimulation of the damaged hemisphere. In such cases, excitatory stimulation of the non-damaged hemisphere might be considered. Here we asked whether tDCS exerts a measurable effect on movement quality of the hemiparetic upper limb, following just a single treatment session. Such effect may inform on the hemisphere that should be excited. Using a single-blinded crossover experimental design, stroke patients and healthy control subjects were assessed before and after anodal, cathodal and sham tDCS, each provided during a single session of reaching training (repeated point-to-point hand movement on an electronic tablet). Group comparisons of endpoint kinematics at baseline-number of peaks in the speed profile (NoP; smoothness), hand-path deviations from the straight line (SLD; accuracy) and movement time (MT; speed)-disclosed greater NoP, larger SLD and longer MT in the stroke group. NoP and MT revealed an advantage for anodal compared to sham stimulation of the lesioned hemisphere. NoP and MT improvements under anodal stimulation of the non-lesioned hemisphere correlated positively with the severity of hemiparesis. Damage to specific cortical regions and white-matter tracts was associated with lower kinematic gains from tDCS. The study shows that simple descriptors of movement kinematics of the hemiparetic upper limb are sensitive enough to demonstrate gain from neuromodulation by tDCS, following just a single session of reaching training. Moreover, the results show that tDCS-related gain is affected by the severity of baseline motor impairment, and by lesion topography. |
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Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel. nachum@soroker.online |
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2045-2322 |
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PMID:38796610; PMCID:PMC11127956 |
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125 |
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Author |
Davidowitz, I.; Parmet, Y.; Frenkel-Toledo, S.; Banina, M.C.; Soroker, N.; Solomon, J.M.; Liebermann, D.G.; Levin, M.F.; Berman, S. |
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Title |
Relationship Between Spasticity and Upper-Limb Movement Disorders in Individuals With Subacute Stroke Using Stochastic Spatiotemporal Modeling |
Type |
Journal Article |
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Year |
2019 |
Publication |
Neurorehabilitation and Neural Repair |
Abbreviated Journal |
Neurorehabil Neural Repair |
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Volume |
33 |
Issue |
2 |
Pages |
141-152 |
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Keywords |
Gaussian mixture model; Kullback-Liebler divergence; spasticity; stroke; upper-limb kinematics |
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Abstract |
BACKGROUND: Spasticity is common in patients with stroke, yet current quantification methods are insufficient for determining the relationship between spasticity and voluntary movement deficits. This is partly a result of the effects of spasticity on spatiotemporal characteristics of movement and the variability of voluntary movement. These can be captured by Gaussian mixture models (GMMs). OBJECTIVES: To determine the influence of spasticity on upper-limb voluntary motion, as assessed by the bidirectional Kullback-Liebler divergence (BKLD) between motion GMMs. METHODS: A total of 16 individuals with subacute stroke and 13 healthy aged-equivalent controls reached to grasp 4 targets (near-center, contralateral, far-center, and ipsilateral). Two-dimensional GMMs (angle and time) were estimated for elbow extension motion. BKLD was computed for each individual and target, within the control group and between the control and stroke groups. Movement time, final elbow angle, average elbow velocity, and velocity smoothness were computed. RESULTS: Between-group BKLDs were much larger than within control-group BKLDs. Between-group BKLDs for the near-center target were lower than those for the far-center and contralateral targets, but similar to that for the ipsilateral target. For those with stroke, the final angle was lower for the near-center target, and the average velocity was higher. Velocity smoothness was lower for the near-center than for the ipsilateral target. Elbow flexor and extensor passive muscle resistance (Modified Ashworth Scale) strongly explained BKLD values. CONCLUSIONS: Results support the view that individuals with poststroke spasticity have a velocity-dependent reduction in active elbow joint range and that BKLD can be used as an objective measure of the effects of spasticity on reaching kinematics. |
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1 Ben-Gurion University of the Negev, Beer-Sheva, Israel |
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1545-9683 |
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PMID:30744528 |
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93 |
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Author |
Frenkel-Toledo, S.; Yamanaka, J.; Friedman, J.; Feldman, A.G.; Levin, M.F. |
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Title |
Referent control of anticipatory grip force during reaching in stroke: an experimental and modeling study |
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Journal Article |
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Year |
2019 |
Publication |
Experimental Brain Research |
Abbreviated Journal |
Exp Brain Res |
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Volume |
237 |
Issue |
7 |
Pages |
1655-1672 |
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Keywords |
Anticipatory grip force; Referent control; Stroke |
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To evaluate normal and impaired control of anticipatory grip force (GF) modulation, we compared GF production during horizontal arm movements in healthy and post-stroke subjects, and, based on a physiologically feasible dynamic model, determined referent control variables underlying the GF-arm motion coordination in each group. 63% of 13 healthy and 48% of 13 stroke subjects produced low sustained initial force (< 10 N) and increased GF prior to arm movement. Movement-related GF increases were higher during fast compared to self-paced arm extension movements only in the healthy group. Differences in the patterns of anticipatory GF increases before the arm movement onset between groups occurred during fast extension arm movement only. In the stroke group, longer delays between the onset of GF change and elbow motion were related to clinical upper limb deficits. Simulations showed that GFs could emerge from the difference between the actual and the referent hand aperture (Ra) specified by the CNS. Similarly, arm movement could result from changes in the referent elbow position (Re) and could be affected by the co-activation (C) command. A subgroup of stroke subjects, who increased GF before arm movement, could specify different patterns of the referent variables while reproducing the healthy typical pattern of GF-arm coordination. Stroke subjects, who increased GF after arm movement onset, also used different referent strategies than controls. Thus, altered anticipatory GF behavior in stroke subjects may be explained by deficits in referent control. |
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0014-4819 |
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PMID:30976821 |
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98 |
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