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Author Biess, A.; Flash, T.; Liebermann, D.G. url  openurl
  Title Riemannian geometric approach to human arm dynamics, movement optimization, and invariance Type Journal Article
  Year 2011 Publication Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics Abbreviated Journal Phys Rev E Stat Nonlin Soft Matter Phys  
  Volume 83 Issue 3 Pt 1 Pages 031927  
  Keywords Arm/*physiology; Biomechanics; Computer Simulation; Humans; Kinetics; Male; Models, Biological; Models, Statistical; Models, Theoretical; *Movement; Psychomotor Performance/*physiology; Range of Motion, Articular/physiology; Reaction Time/physiology; Space Perception/*physiology; Torque  
  Abstract We present a generally covariant formulation of human arm dynamics and optimization principles in Riemannian configuration space. We extend the one-parameter family of mean-squared-derivative (MSD) cost functionals from Euclidean to Riemannian space, and we show that they are mathematically identical to the corresponding dynamic costs when formulated in a Riemannian space equipped with the kinetic energy metric. In particular, we derive the equivalence of the minimum-jerk and minimum-torque change models in this metric space. Solutions of the one-parameter family of MSD variational problems in Riemannian space are given by (reparameterized) geodesic paths, which correspond to movements with least muscular effort. Finally, movement invariants are derived from symmetries of the Riemannian manifold. We argue that the geometrical structure imposed on the arm's configuration space may provide insights into the emerging properties of the movements generated by the motor system.  
  Address Bernstein Center for Computational Neuroscience, DE-37073 Gottingen, Germany. armin@nld.ds.mpg.de  
  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 (up) 1539-3755 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:21517543 Approved no  
  Call Number Serial 29  
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Author Liebermann, D.G.; Levin, M.F.; McIntyre, J.; Weiss, P.L.; Berman, S. url  doi
openurl 
  Title Arm path fragmentation and spatiotemporal features of hand reaching in healthy subjects and stroke patients Type Journal Article
  Year 2010 Publication Conference Proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference Abbreviated Journal Conf Proc IEEE Eng Med Biol Soc  
  Volume 2010 Issue Pages 5242-5245  
  Keywords Aged; Aged, 80 and over; Analysis of Variance; Arm/*physiology; Biomechanics/physiology; Female; Hand/*physiology; *Health; Humans; Male; Middle Aged; Movement/*physiology; Posture/physiology; Principal Component Analysis; Stroke/*physiopathology; Time Factors  
  Abstract Arm motion in healthy humans is characterized by smooth and relatively short paths. The current study focused on 3D reaching in stroke patients. Sixteen right-hemiparetic stroke patients and 8 healthy adults performed 42 reaching movements towards 3 visual targets located at an extended arm distance. Performance was assessed in terms of spatial and temporal features of the movement; i.e., hand path, arm posture and smoothness. Differences between groups and within subjects were hypothesized for spatial and temporal aspects of reaching under the assumption that both are independent. As expected, upper limb motion of patients was characterized by longer and jerkier hand paths and slower speeds. Assessment of the number of sub-movements within each movement did not clearly discriminate between groups. Principal component analyses revealed specific clusters of either spatial or temporal measures, which accounted for a large proportion of the variance in patients but not in healthy controls. These findings support the notion of a separation between spatial and temporal features of movement. Stroke patients may fail to integrate the two aspects when executing reaching movements towards visual targets.  
  Address Physical Therapy Dept., Sackler Faculty of Medicine, Tel Aviv University, 69978 Israel. dlieberm@post.tau.ac.il  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 1557-170X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:21096047 Approved no  
  Call Number Serial 30  
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