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Liebermann, D.G.; Biess, A.; Friedman, J.; Gielen, C.C.A.M.; Flash, T. | ||||
| Title | Intrinsic joint kinematic planning. I: reassessing the Listing's law constraint in the control of three-dimensional arm movements | Type | Journal Article | ||
| Year | 2006 | Publication | Experimental Brain Research | Abbreviated Journal | Exp Brain Res |
| Volume | 171 | Issue | 2 | Pages | 139-154 |
| Keywords | Adolescent; Adult; Analysis of Variance; *Arm; Biomechanics; Eye Movements/*physiology; Humans; Joints/*physiology; Male; Movement/*physiology; *Musculoskeletal System; Orientation/*physiology; Posture | ||||
| Abstract | 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. | ||||
| Address | Department of Physical Therapy, Sackler Faculty of Medicine, Tel-Aviv University, 69978, Ramat Aviv, Israel. dlieberm@post.tau.ac.il | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0014-4819 | ISBN | Medium | ||
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| Notes | PMID:16341526 | Approved | no | ||
| Call Number | Penn State @ write.to.jason @ | Serial | 18 | ||
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| Author |
Levin, M.F.; Liebermann, D.G.; Parmet, Y.; Berman, S. | ||||
| 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 | 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 | ||
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| ISSN | 1545-9683 | ISBN | Medium | ||
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| Notes | PMID:26510934 | Approved | no | ||
| Call Number | Serial | 79 | |||
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| Author |
Harel Arzi; Tal Krasovsky; Moshe Pritsch; Dario G. Liebermann | ||||
| Title | Movement control in patients with shoulder instability: a comparison between patients after open surgery and nonoperated patients | Type | Journal Article | ||
| Year | 2014 | Publication | Journal of Shoulder and Elbow Surgery | Abbreviated Journal | |
| Volume | 23 | Issue | 7 | Pages | 982–992 |
| Keywords | Smoothness; kinesthesis; arm kinematics; shoulder instability; open surgery | ||||
| Abstract | Background Open surgery to correct shoulder instability is deemed to facilitate recovery of static and dynamic motor functions. Postoperative assessments focus primarily on static outcomes (e.g., repositioning accuracy). We introduce kinematic measures of arm smoothness to assess shoulder patients after open surgery and compare them with nonoperated patients. Performance among both groups of patients was hypothesized to differ. Postsurgery patients were expected to match healthy controls. Methods All participants performed pointing movements with the affected/dominant arm fully extended at fast, preferred, and slow speeds (36 trials per subject). Kinematic data were collected (100 Hz, 3 seconds), and mixed-design analyses of variance (group, speed) were performed with movement time, movement amplitude, acceleration time, and model-observed similarities as dependent variables. Nonparametric tests were performed for number of velocity peaks. Results Nonoperated and postsurgery patients showed similarities at preferred and faster movement speeds but not at slower speed. Postsurgery patients were closer to maximally smoothed motion and differed from healthy controls mainly during slow arm movements (closer to maximal smoothness, larger movement amplitude, shorter movement time, and lower number of peaks; i.e., less movement fragmentation). Conclusions Arm kinematic analyses suggest that open surgery stabilizes the shoulder but does not necessarily restore normal movement quality. Patients with recurrent anterior shoulder instability (RASI) seem to implement a “safe” but nonadaptive mode of action whereby preplanned stereotypical movements may be executed without depending on feedback. Rehabilitation of RASI patients should focus on restoring feedback-based movement control. Clinical assessment of RASI patients should include higher order kinematic descriptors. |
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| Notes | Approved | no | |||
| Call Number | Serial | 74 | |||
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| Author |
Friedman, Jason; Brown, Scott; Finkbeiner, Matthew | ||||
| Title | Linking cognitive and reaching trajectories via intermittent movement control | Type | Journal Article | ||
| Year | 2013 | Publication | Journal of Mathematical Psychology | Abbreviated Journal | |
| Volume | 57 | Issue | 3-4 | Pages | 140-151 |
| Keywords | Decision making; Diffusion model; Reaction times; Arm movements; Submovements | ||||
| Abstract | Theories of decision-making have traditionally been constrained by reaction time data. A limitation of reaction time data, particularly for studying the temporal dynamics of cognitive processing, is that they index only the endpoint of the decision making process. Recently, physical reaching trajectories have been used as proxies for underlying mental trajectories through decision space. We suggest that this approach has been oversimplified: while it is possible for the motor control system to access the current state of the evidence accumulation process, this access is intermittent. Instead, we demonstrate how a model of arm movements that assumes intermittent, not continuous, access to the decision process is sufficient to describe the effects of stimulus quality and viewing time in curved reaching movements. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 70 | |||
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| Author |
Biess, A.; Liebermann, D.G.; Flash, T. | ||||
| Title | A computational model for redundant human three-dimensional pointing movements: integration of independent spatial and temporal motor plans simplifies movement dynamics | Type | Journal Article | ||
| Year | 2007 | Publication | The Journal of Neuroscience : the Official Journal of the Society for Neuroscience | Abbreviated Journal | J Neurosci |
| Volume | 27 | Issue | 48 | Pages | 13045-13064 |
| Keywords | Analysis of Variance; Arm/physiology; Biomechanics; *Computer Simulation; Humans; *Models, Biological; Movement/*physiology; *Nonlinear Dynamics; Posture/physiology; Psychomotor Performance/*physiology; Range of Motion, Articular/physiology; Reaction Time/physiology; Space Perception/*physiology; Time Factors; Torque | ||||
| Abstract | Few computational models have addressed the spatiotemporal features of unconstrained three-dimensional (3D) arm motion. Empirical observations made on hand paths, speed profiles, and arm postures during point-to-point movements led to the assumption that hand path and arm posture are independent of movement speed, suggesting that the geometric and temporal properties of movements are decoupled. In this study, we present a computational model of 3D movements for an arm with four degrees of freedom based on the assumption that optimization principles are separately applied at the geometric and temporal levels of control. Geometric properties (path and posture) are defined in terms of geodesic paths with respect to the kinetic energy metric in the Riemannian configuration space. Accordingly, a geodesic path can be generated with less muscular effort than on any other, nongeodesic path, because the sum of all configuration-speed-dependent torques vanishes. The temporal properties of the movement (speed) are determined in task space by minimizing the squared jerk along the selected end-effector path. The integration of both planning levels into a single spatiotemporal representation simplifies the control of arm dynamics along geodesic paths and results in movements with near minimal torque change and minimal peak value of kinetic energy. Thus, the application of Riemannian geometry allows for a reconciliation of computational models previously proposed for the description of arm movements. We suggest that geodesics are an emergent property of the motor system through the exploration of dynamical space. Our data validated the predictions for joint trajectories, hand paths, final postures, speed profiles, and driving torques. | ||||
| Address | Department of Mathematics, Weizmann Institute of Science, 76100 Rehovot, Israel. armin.biess@weizmann.ac.il | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0270-6474 | ISBN | Medium | ||
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| Notes | PMID:18045899 | Approved | no | ||
| Call Number | Serial | 35 | |||
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