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Author Noy, L.; Alon, U.; Friedman, J. pdf  url
doi  openurl
  Title Corrective jitter motion shows similar individual frequencies for the arm and the finger Type Journal Article
  Year 2015 Publication Experimental Brain Research Abbreviated Journal Exp Brain Res  
  Volume 233 Issue 4 Pages 1307-1320  
  Keywords (up)  
  Abstract A characteristic of visuomotor tracking of non-regular oscillating stimuli are high-frequency jittery corrective motions, oscillating around the tracked stimuli. However, the properties of these corrective jitter responses are not well understood. For example, does the jitter response show an idiosyncratic signature? What is the relationship between stimuli properties and jitter properties? Is the jitter response similar across effectors with different inertial properties? To answer these questions, we measured participants' jitter frequencies in two tracking tasks in the arm and the finger. Thirty participants tracked the same set of eleven non-regular oscillating stimuli, vertically moving on a screen, once with forward-backward arm movements (holding a tablet stylus) and once with upward-downward index finger movements (with a motion tracker attached). Participants' jitter frequencies and tracking errors varied systematically as a function of stimuli frequency and amplitude. Additionally, there were clear individual differences in average jitter frequencies between participants, ranging from 0.7 to 1.15 Hz, similar to values reported previously. A comparison of individual jitter frequencies in the two tasks showed a strong correlation between participants' jitter frequencies in the finger and the arm, despite the very different inertial properties of the two effectors. This result suggests that the corrective jitter response stems from common neural processes.  
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  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0014-4819 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:25630905 Approved no  
  Call Number Serial 76  
Permanent link to this record
 

 
Author Levin, M.F.; Liebermann, D.G.; Parmet, Y.; Berman, S. url  doi
openurl 
  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  
  Volume Issue Pages  
  Keywords (up) 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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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1545-9683 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:26510934 Approved no  
  Call Number Serial 79  
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Author Portnoy, S.; Rosenberg, L.; Alazraki, T.; Elyakim, E.; Friedman, J. pdf  url
doi  openurl
  Title Differences in Muscle Activity Patterns and Graphical Product Quality in Children Copying and Tracing Activities on Horizontal or Vertical Surfaces Type Journal Article
  Year 2015 Publication Journal of Electromyography and Kinesiology Abbreviated Journal Journal of Electromyography and Kinesiology  
  Volume 25 Issue 3 Pages 540�547  
  Keywords (up) Motor equivalence; Electromyography; Tablet; Occupational Therapy; Muscle fatigue; Motor control  
  Abstract The observation that a given task, e.g. producing a signature, looks similar when created by different motor commands and different muscles groups is known as motor equivalence. Relatively little data exists regarding the characteristics of motor equivalence in children. In this study, we compared the level of performance when performing a tracing task and copying figures in two common postures: while sitting at a desk and while standing in front of a wall, among preschool children. In addition, we compared muscle activity patterns in both postures. Specifically, we compared the movements of 35 five- to six-year old children, recording the same movements of copying figures and path tracing on an electronic tablet in both a horizontal orientation, while sitting, and a vertical orientation, while standing. Different muscle activation patterns were observed between the postures, however no significant difference in the performance level was found, providing evidence of motor equivalence at this young age. The study presents a straightforward method of assessing motor equivalence that can be extended to other stages of development as well as motor disorders.  
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  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1050-6411 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 77  
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Author Zopf, R.; Friedman, J.; Williams, M.A. pdf  url
doi  openurl
  Title The plausibility of visual information for hand ownership modulates multisensory synchrony perception Type Journal Article
  Year 2015 Publication Abbreviated Journal Experimental Brain Research  
  Volume 233 Issue 8 Pages 2311-2321  
  Keywords (up) Multisensory perception; Temporal synchrony perception; Virtual hand; Body representations; Body ownership; Sensory predictions  
  Abstract We are frequently changing the position of our bodies and body parts within complex environments. How does the brain keep track of one’s own body? Current models of body ownership state that visual body ownership cues such as viewed object form and orientation are combined with multisensory information to correctly identify one’s own body, estimate its current location and evoke an experience of body ownership. Within this framework, it may be possible that the brain relies on a separate perceptual analysis of body ownership cues (e.g. form, orientation, multisensory synchrony). Alternatively, these cues may interact in earlier stages of perceptual processing—visually derived body form and orientation cues may, for example, directly modulate temporal synchrony perception. The aim of the present study was to distinguish between these two alternatives. We employed a virtual hand set-up and psychophysical methods. In a two-interval force-choice task, participants were asked to detect temporal delays between executed index finger movements and observed movements. We found that body-specifying cues interact in perceptual processing. Specifically, we show that plausible visual information (both form and orientation) for one’s own body led to significantly better detection performance for small multisensory asynchronies compared to implausible visual information. We suggest that this perceptual modulation when visual information plausible for one’s own body is present is a consequence of body-specific sensory predictions.  
  Address  
  Corporate Author Thesis  
  Publisher Springer Berlin Heidelberg Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0014-4819 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 78  
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