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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. url  doi
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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
  Year 2019 Publication Neurorehabilitation and Neural Repair Abbreviated Journal Neurorehabil Neural Repair  
  Volume 33 Issue 2 Pages (up) 141-152  
  Keywords Gaussian mixture model; Kullback-Liebler divergence; spasticity; stroke; upper-limb kinematics  
  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.  
  Address 1 Ben-Gurion University of the Negev, Beer-Sheva, Israel  
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  ISSN 1545-9683 ISBN Medium  
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  Notes PMID:30744528 Approved no  
  Call Number Serial 93  
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Author Liebermann, D.G.; Issurin V. openurl 
  Title Effects of vibratory stimulation on the perception of effort during isotonic contractions Type Journal Article
  Year 1997 Publication Journal of Human Movement Studies Abbreviated Journal  
  Volume 32 Issue Pages (up) 171-186  
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  Call Number Serial 61  
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Author Liebermann, D.G.; Berman, S.; Weingarden H.; Levin, M.F.; Weiss, P.L. doi  openurl
  Title Kinematic features of arm and trunk movements in stroke patients and age-matched healthy controls during reaching in virtual and physical environments Type Conference Article
  Year 2009 Publication Virtual Rehabilitation International Conference Abbreviated Journal  
  Volume Issue Pages (up) 179-184  
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  Abstract Motor performance of stroke patients and healthy individuals was compared in terms of selected kinematic features of arm and trunk movements while subjects reached for visual targets in virtual (VR) and physical (PH) environments. In PH, the targets were placed at an extended arm distance, while in VR comparably placed virtual targets were presented via GestureTek's IREX system. Our goal was to obtain further insights into research methods related to VR-based rehabilitation. Eight right-hemiparetic stroke patients (age =46-87 years) and 8 healthy adults (age =51-73 years) completed 84 reaching movements in VR and PH environments while seated. The results showed that arm and trunk movements differed in the two environments in patients and to a lesser extent in healthy individuals. Arm motion of patients became jerkier in VR, with larger paths and longer movement durations, and presented greater arm torsion (i.e., larger elbow rotations around the hand-shoulder axis). Interestingly, patients also showed a significant reduction of compensatory trunk movements during VR reaching. The findings indicate that when targets were perceived to be beyond hand reach, stroke patients may be less able to estimate 3D virtual target locations obtained from the 2D TV planar displays. This was not the case for healthy participants.  
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  Notes Approved no  
  Call Number Serial 52  
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Author Liebermann, D.G.; Raz, T.; Dickinson, J. openurl 
  Title On Intentional and Incidental Learning and Estimation of Temporal and Spatial Information Type Journal Article
  Year 1988 Publication Journal of Human Movement Studies Abbreviated Journal  
  Volume 15 Issue Pages (up) 191-204  
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  Call Number Serial 54  
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Author Liebermann, D.G.; Goodman, D. url  doi
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  Title Pre-landing muscle timing and post-landing effects of falling with continuous vision and in blindfold conditions Type Journal Article
  Year 2007 Publication Journal of Electromyography and Kinesiology : Official Journal of the International Society of Electrophysiological Kinesiology Abbreviated Journal J Electromyogr Kinesiol  
  Volume 17 Issue 2 Pages (up) 212-227  
  Keywords Adult; Analysis of Variance; Biomechanics; *Blindness; *Electromyography; Humans; Joints/physiology; Lower Extremity/physiology; Male; Movement/*physiology; Muscle, Skeletal/*physiology; Orientation; *Vision, Ocular  
  Abstract The present study examined the effect of continuous vision and its occlusion in timing of pre-landing actions during free falls. When vision is occluded, muscle activation is hypothesized to start relative to onset of the fall. However, when continuous vision is available onset of action is hypothesized to be relative to the moment of touchdown. Six subjects performed 6 randomized sets of 6 trials after becoming familiar with the task. The 36 trials were divided in 2 visual conditions (vision and blindfold) and 3 heights of fall (15, 45 and 75 cm). EMG activity was recorded from the gastrocnemius and rectus femoris muscles during the falls. The latency of onset (L(o)) and the lapse from EMG onset to touchdown (T(c)) were obtained from these muscles. Vertical forces were recorded to assess the effects of pre-landing activity on the impacts at collision with and without continuous vision. Peak amplitude (F(max)), time to peak (T(max)) and peak impulse normalized to momentum (I(norm)) were used as outcome measures. Within flight time ranges of approximately 50-400 ms, the results showed that L(o) and T(c) follow a similar linear trend whether continuous vision was available or occluded. However, the variability of T(c) for each of the muscles was larger in the vision occluded condition. Analyses of variance showed that the rectus femoris muscle started consistently earlier in no vision trials. Finally, impact forces were not different in vision or blindfold conditions, and thus, they were not affected by minor differences in the timing of muscles prior to landing. Thus, it appears that knowing the surroundings before falling may help to reduce the need for a continuous visual input. The relevance of such input cannot be ruled out for falls from high landing heights, but cognitive factors (e.g., attention to specific cues and anticipation of a fall) may play a dominant role in timing actions during short duration falls encountered daily.  
  Address Physical Therapy Department, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel. dlieberm@post.tau.ac.il <dlieberm@post.tau.ac.il>  
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  ISSN 1050-6411 ISBN Medium  
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  Notes PMID:16600637 Approved no  
  Call Number Serial 37  
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