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Author Frenkel-Toledo, S.; Yamanaka, J.; Friedman, J.; Feldman, A.G.; Levin, M.F. pdf  url
doi  openurl
  Title (up) Referent control of anticipatory grip force during reaching in stroke: an experimental and modeling study Type Journal Article
  Year 2019 Publication Experimental Brain Research Abbreviated Journal Exp Brain Res  
  Volume 237 Issue 7 Pages 1655-1672  
  Keywords Anticipatory grip force; Referent control; Stroke  
  Abstract 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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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 0014-4819 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30976821 Approved no  
  Call Number Serial 98  
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Author Krasovsky, T.; Keren-Capelovitch, T.; Friedman, J.; Weiss, P.L. pdf  url
doi  openurl
  Title (up) Self-feeding kinematics in an ecological setting: typically developing children and children with cerebral palsy Type Journal Article
  Year 2021 Publication IEEE Transactions on Neural Systems and Rehabilitation Engineering : a Publication of the IEEE Engineering in Medicine and Biology Society Abbreviated Journal IEEE Trans Neural Syst Rehabil Eng  
  Volume 29 Issue Pages 1462-1469  
  Keywords  
  Abstract Assessment of self-feeding kinematics is seldom performed in an ecological setting. In preparation for development of an instrumented spoon for measurement of self-feeding in children with cerebral palsy (CP), the current work aimed to evaluate upper extremity kinematics of self-feeding in young children with typical development (TD) and a small, age-matched group of children with CP in a familiar setting, while eating with a spoon. METHODS: Sixty-five TD participants and six children diagnosed with spastic CP, aged 3-9 years, fed themselves while feeding was measured using miniature three-dimensional motion capture sensors (trakStar). Kinematic variables associated with different phases of self-feeding cycle (movement time, curvature, time to peak velocity and smoothness) were compared across age-groups in the TD sample and between TD children and those with CP. RESULTS: Significant between-age group differences were identified in movement times, time to peak velocity and curvature. Children with CP demonstrated slower, less smooth self-feeding movements, potentially related to activity limitations. CONCLUSIONS: The identified kinematic variables form a basis for implementation of self-feeding performance assessment in children of different ages, including those with CP, which can be deployed via an instrumented spoon.  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1534-4320 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:34280104 Approved no  
  Call Number Serial 110  
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Author Swissa, Y.; Hacohen, S.; Friedman, J.; Frenkel-Toledo, S. pdf  url
doi  openurl
  Title (up) Sensorimotor performance after high-definition transcranial direct current stimulation over the primary somatosensory or motor cortices in men versus women Type Journal Article
  Year 2022 Publication Scientific Reports Abbreviated Journal Sci Rep  
  Volume 12 Issue Pages 11117  
  Keywords  
  Abstract The primary somatosensory (S1) cortex is a central structure in motor performance. However, transcranial direct current stimulation (tDCS) research aimed at improving motor performance usually targets the primary motor cortex (M1). Recently, sex was found to mediate tDCS response. Thus, we investigated whether tDCS with an anodal electrode placed over S1 improves motor performance and sensation perception in men versus women. Forty-five participants randomly received 15-min high-definition tDCS (HD-tDCS) at 1 mA to S1, M1, or sham stimulation. Reaching performance was tested before and immediately following stimulation. Two-point orientation discrimination (TPOD) of fingers and proprioception of a reaching movement were also tested. Although motor performance did not differ between groups, reaching reaction time improved in the M1 group men. Reaching movement time and endpoint error improved in women and men, respectively. Correct trials percentage for TPOD task was higher in the S1 compared to the M1 group in the posttest and improved only in the S1 group. Reaching movement time for the proprioception task improved, overall, and endpoint error did not change. Despite the reciprocal connections between S1 and M1, effects of active tDCS over S1 and M1 may specifically influence sensation perception and motor performance, respectively. Also, sex may mediate effects of HD-tDCS on motor performance.  
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  Series Volume Series Issue Edition  
  ISSN 2045-2322 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 114  
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Author Noy, L.; Weiser, N.; Friedman, J. pdf  url
doi  openurl
  Title (up) Synchrony in Joint Action Is Directed by Each Participant's Motor Control System Type Journal Article
  Year 2017 Publication Frontiers in Psychology Abbreviated Journal Front. Psychol.  
  Volume 8 Issue Pages 531  
  Keywords visuomotor tracking; mirror game; intermittent control; joint action; motor control  
  Abstract In this work, we ask how the probability of achieving synchrony in joint action is affected by the choice of motion parameters of each individual. We use the mirror game paradigm to study how changes in leader&#65533;s motion parameters, specifically frequency and peak velocity, affect the probability of entering the state of co-confidence (CC) motion: a dyadic state of synchronized, smooth and co-predictive motions. In order to systematically study this question, we used a one-person version of the mirror game, where the participant mirrored piece-wise rhythmic movements produced by a computer on a graphics tablet. We systematically varied the frequency and peak velocity of the movements to determine how these parameters affect the likelihood of synchronized joint action. To assess synchrony in the mirror game we used the previously developed marker of co-confident (CC) motions: smooth, jitter-less and synchronized motions indicative of co-predicative control. We found that when mirroring movements with low frequencies (i.e., long duration movements), the participants never showed CC, and as the frequency of the stimuli increased, the probability of observing CC also increased. This finding is discussed in the framework of motor control studies showing an upper limit on the duration of smooth motion. We confirmed the relationship between motion parameters and the probability to perform CC with three sets of data of open-ended two-player mirror games. These findings demonstrate that when performing movements together, there are optimal movement frequencies to use in order to maximize the possibility of entering a state of synchronized joint action. It also shows that the ability to perform synchronized joint action is constrained by the properties of our motor control systems.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1664-1078 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 84  
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Author Lerner, O.; Friedman, J.; Frenkel-Toledo, S. pdf  url
doi  openurl
  Title (up) The effect of high-definition transcranial direct current stimulation intensity on motor performance in healthy adults: a randomized controlled trial Type Journal Article
  Year 2021 Publication Journal of NeuroEngineering and Rehabilitation Abbreviated Journal J NeuroEngineering Rehabil  
  Volume 18 Issue Pages 103  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1743-0003 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 109  
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