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Ezrati, O.; Friedman, J.; Dar, R. | ||||
Title | Attenuation of access to internal states in high obsessive-compulsive individuals might increase susceptibility to false feedback: Evidence from a visuo-motor hand-reaching task | Type | Journal Article | ||
Year | 2019 | Publication | Journal of Behavior Therapy and Experimental Psychiatry | Abbreviated Journal | Journal of Behavior Therapy and Experimental Psychiatry |
Volume | 65 | Issue | Pages | 101445 | |
Keywords | Obsessive-compulsive disorder; Movement; Agency; Proprioception; Proxies | ||||
Abstract | Background and objectives The Seeking Proxies for Internal States (SPIS) model of obsessive-compulsive disorder (OCD) posits that obsessive-compulsive (OC) individuals have attenuated access to their internal states. Hence, they seek and rely on proxies, or discernible substitutes for these internal states. In previous studies, participants with high OC tendencies and OCD patients, compared to controls, showed increased reliance on external proxies and were more influenced by false feedback when judging their internal states. This study is the first to examine the effects of false feedback on performance of hand movements in participants with high and low OC tendencies. Method Thirty-four participants with high OC tendencies and 34 participants with low OC tendencies were asked to perform accurate hand reaches without visual feedback in two separate sessions of a computerized hand-reaching task: once after valid feedback training of their hand location and once with false-rotated feedback. We assessed the accuracy and directional adaptation of participants' reaches. Results As predicted, high OC participants evidenced a larger decrease in their hand positioning accuracy after training with false feedback compared to low OC participants. Limitations The generalization of our findings to OCD requires replication with a clinical sample. Conclusions These results suggest that in addition to self-perceptions, motor performance of OC individuals is prone to be overly influenced by false feedback, possibly due to attenuated access to proprioceptive cues. These findings may be particularly relevant to understanding the distorted sense of agency in OCD. |
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Language | Summary Language | Original Title | |||
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ISSN | 0005-7916 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | Serial | 95 | |||
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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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Publisher | Place of Publication | Editor | |||
Language | English | Summary Language | Original Title | ||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0270-6474 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | PMID:18045899 | Approved | no | ||
Call Number | Serial | 35 | |||
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Author ![]() |
Biess, A.; Flash, T.; Liebermann, D.G. | ||||
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 | ||||
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Publisher | Place of Publication | Editor | |||
Language | English | Summary Language | Original Title | ||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1539-3755 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | PMID:21517543 | Approved | no | ||
Call Number | Serial | 29 | |||
Permanent link to this record |