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Grinberg, A.; Strong, A.; Strandberg, J.; Selling, J.; Liebermann, D.G.; Bjorklund, M.; Hager, C.K. |
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Title |
Electrocortical activity associated with movement-related fear: a methodological exploration of a threat-conditioning paradigm involving destabilising perturbations during quiet standing |
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Journal Article |
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Year |
2024 |
Publication |
Experimental Brain Research |
Abbreviated Journal |
Exp Brain Res |
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Cnv; Eeg; Erp; Kinesiophobia; Moving platform; Re-injury anxiety |
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Musculoskeletal trauma often leads to lasting psychological impacts stemming from concerns of future injuries. Often referred to as kinesiophobia or re-injury anxiety, such concerns have been shown to hinder return to physical activity and are believed to increase the risk for secondary injuries. Screening for re-injury anxiety is currently restricted to subjective questionnaires, which are prone to self-report bias. We introduce a novel approach to objectively identify electrocortical activity associated with the threat of destabilising perturbations. We aimed to explore its feasibility among non-injured persons, with potential future implementation for screening of re-injury anxiety. Twenty-three participants stood blindfolded on a translational balance perturbation platform. Consecutive auditory stimuli were provided as low (neutral stimulus [CS(-)]) or high (conditioned stimulus [CS(+)]) tones. For the main experimental protocol (Protocol I), half of the high tones were followed by a perturbation in one of eight unpredictable directions. A separate validation protocol (Protocol II) requiring voluntary squatting without perturbations was performed with 12 participants. Event-related potentials (ERP) were computed from electroencephalography recordings and significant time-domain components were detected using an interval-wise testing procedure. High-amplitude early contingent negative variation (CNV) waves were significantly greater for CS(+) compared with CS(-) trials in all channels for Protocol I (> 521-800ms), most prominently over frontal and central midline locations (P </= 0.001). For Protocol II, shorter frontal ERP components were observed (541-609ms). Our test paradigm revealed electrocortical activation possibly associated with movement-related fear. Exploring the discriminative validity of the paradigm among individuals with and without self-reported re-injury anxiety is warranted. |
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Department of Community Medicine and Rehabilitation, Umea University, Umea, Sweden |
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0014-4819 |
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PMID:38896295 |
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122 |
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Author |
Friedman, Jason; Flash, Tamar |
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Title |
Trajectory of the index finger during grasping |
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Journal Article |
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Year |
2009 |
Publication |
Experimental Brain Research |
Abbreviated Journal |
Exp Brain Res |
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196 |
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4 |
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497-509 |
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The trajectory of the index finger during grasping movements was compared to the trajectories predicted by three optimization-based models. The three models consisted of minimizing the integral of the weighted squared joint derivatives along the path (inertia-like cost), minimizing torque change, and minimizing angular jerk. Of the three models, it was observed that the path of the fingertip and the joint trajectories, were best described by the minimum angular jerk model. This model, which does not take into account the dynamics of the finger, performed equally well when the inertia of the finger was altered by adding a 20 g weight to the medial phalange. Thus, for the finger, it appears that trajectories are planned based primarily on kinematic considerations at a joint level. |
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Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel, write.to.jason@gmail.com |
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1432-1106 |
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PMID:19521692 |
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Penn State @ write.to.jason @ |
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17 |
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Liebermann, D.G.; Biess, A.; Friedman, J.; Gielen, C.C.A.M.; Flash, T. |
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Intrinsic joint kinematic planning. I: reassessing the Listing's law constraint in the control of three-dimensional arm movements |
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Journal Article |
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2006 |
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Experimental Brain Research |
Abbreviated Journal |
Exp Brain Res |
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171 |
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2 |
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139-154 |
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Adolescent; Adult; Analysis of Variance; *Arm; Biomechanics; Eye Movements/*physiology; Humans; Joints/*physiology; Male; Movement/*physiology; *Musculoskeletal System; Orientation/*physiology; Posture |
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This study tested the validity of the assumption that intrinsic kinematic constraints, such as Listing's law, can account for the geometric features of three-dimensional arm movements. In principle, if the arm joints follow a Listing's constraint, the hand paths may be predicted. Four individuals performed 'extended arm', 'radial', 'frontal plane', and 'random mixed' movements to visual targets to test Listing's law assumption. Three-dimensional rotation vectors of the upper arm and forearm were calculated from three-dimensional marker data. Data fitting techniques were used to test Donders' and Listing's laws. The coefficient values obtained from fitting rotation vectors to the surfaces described by a second-order equation were analyzed. The results showed that the coefficients that represent curvature and twist of the surfaces were often not significantly different from zero, particularly not during randomly mixed and extended arm movements. These coefficients for forearm rotations were larger compared to those for the upper arm segment rotations. The mean thickness of the rotation surfaces ranged between approximately 1.7 degrees and 4.7 degrees for the rotation vectors of the upper arm segment and approximately 2.6 degrees and 7.5 degrees for those of the forearm. During frontal plane movements, forearm rotations showed large twist scores while upper arm segment rotations showed large curvatures, although the thickness of the surfaces remained low. The curvatures, but not the thicknesses of the surfaces, were larger for large versus small amplitude radial movements. In conclusion, when examining the surfaces obtained for the different movement types, the rotation vectors may lie within manifolds that are anywhere between curved or twisted manifolds. However, a two-dimensional thick surface may roughly represent a global arm constraint. Our findings suggest that Listing's law is implemented for some types of arm movement, such as pointing to targets with the extended arm and during radial reaching movements. |
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Department of Physical Therapy, Sackler Faculty of Medicine, Tel-Aviv University, 69978, Ramat Aviv, Israel. dlieberm@post.tau.ac.il |
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0014-4819 |
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PMID:16341526 |
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Penn State @ write.to.jason @ |
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18 |
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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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237 |
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7 |
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1655-1672 |
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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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Author |
Friedman, Jason; Latash, Mark L.; Zatsiorsky, Vladimir M. |
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Prehension synergies: a study of digit force adjustments to the continuously varied load force exerted on a partially constrained hand-held object |
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Journal Article |
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2009 |
Publication |
Experimental Brain Research |
Abbreviated Journal |
Exp Brain Res |
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197 |
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1 |
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1-13 |
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We examined how the digit forces adjust when a load force acting on a hand-held object continuously varies. The subjects were required to hold the handle still while a linearly increasing and then decreasing force was applied to the handle. The handle was constrained, such that it could only move up and down, and rotate about a horizontal axis. In addition, the moment arm of the thumb tangential force was 1.5 times the moment arm of the virtual finger (VF, an imagined finger with the mechanical action equal to that of the four fingers) force. Unlike the situation when there are equal moment arms, the experimental setup forced the subjects to choose between (a) sharing equally the increase in load force between the thumb and VF but generating a moment of tangential force, which had to be compensated by negatively co-varying the moment due to normal forces, or (b) sharing unequally the load force increase between the thumb and VF but preventing generation of a moment of tangential forces. We found that different subjects tended to use one of these two strategies. These findings suggest that the selection by the CNS of prehension synergies at the VF-thumb level with respect to the moment of force is non-obligatory and reflects individual subject preferences. This unequal sharing of the load by the tangential forces, in contrast to the previously observed equal sharing, suggests that the invariant feature of prehension may be a correlated increase in tangential forces rather than an equal increase. |
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Department of Kinesiology, The Pennsylvania State University, 39 Recreation Building, University Park, PA, 16802, USA, jason.friedman@psu.edu |
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1432-1106 |
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PMID:19554319 |
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Penn State @ write.to.jason @ |
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16 |
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