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Author Friedman, Jason; Brown, Scott; Finkbeiner, Matthew pdf  doi
openurl 
  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 (up) Approved no  
  Call Number Serial 70  
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Author Friedman, J.; Korman, M. pdf  url
doi  openurl
  Title Offline Optimization of the Relative Timing of Movements in a Sequence Is Blocked by Retroactive Behavioral Interference Type Journal Article
  Year 2016 Publication Frontiers in Human Neuroscience Abbreviated Journal Front. Hum. Neurosci.  
  Volume 10 Issue Pages 623  
  Keywords learning; interference; consolidation; finger movements; kinematics  
  Abstract Acquisition of motor skills often involves the concatenation of single movements into sequences. Along the course of learning, sequential performance becomes progressively faster and smoother, presumably by optimization of both motor planning and motor execution. Following its encoding during training, “how-to” memory undergoes consolidation, reflecting transformations in performance and its neurobiological underpinnings over time. This offline post-training memory process is characterized by two phenomena: reduced sensitivity to interference and the emergence of delayed, typically overnight, gains in performance. Here, using a training protocol that effectively induces motor sequence memory consolidation, we tested temporal and kinematic parameters of performance within (online) and between (offline) sessions, and their sensitivity to retroactive interference. One group learned a given finger-to-thumb opposition sequence (FOS), and showed robust delayed (consolidation) gains in the number of correct sequences performed at 24 h. A second group learned an additional (interference) FOS shortly after the first and did not show delayed gains. Reduction of touch times and inter-movement intervals significantly contributed to the overall offline improvement of performance overnight. However, only the offline inter-movement interval shortening was selectively blocked by the interference experience. Velocity and amplitude, comprising movement time, also significantly changed across the consolidation period but were interference-insensitive. Moreover, they paradoxically canceled out each other. Current results suggest that shifts in the representation of the trained sequence are subserved by multiple processes: from distinct changes in kinematic characteristics of individual finger movements to high-level, temporal reorganization of the movements as a unit. Each of these processes has a distinct time course and a specific susceptibility to retroactive interference. This multiple-component view may bridge the gap in understanding the link between the behavioral changes, which define online and offline learning, and the biological mechanisms that support those changes.  
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  ISSN 1662-5161 ISBN Medium  
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  Notes (up) Approved no  
  Call Number Serial 83  
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Author Ezrati, O.; Friedman, J.; Dar, R. pdf  url
doi  openurl
  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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  ISSN 0005-7916 ISBN Medium  
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  Notes (up) Approved no  
  Call Number Serial 95  
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Author Liebermann, D.G.; Hoffman, J.R. url  doi
openurl 
  Title Timing of preparatory landing responses as a function of availability of optic flow information Type Journal Article
  Year 2005 Publication Journal of Electromyography and Kinesiology : Official Journal of the International Society of Electrophysiological Kinesiology Abbreviated Journal J Electromyogr Kinesiol  
  Volume 15 Issue 1 Pages 120-130  
  Keywords Adult; Cues; Electromyography; Humans; Male; Movement/physiology; Muscle, Skeletal/*physiology; Posture/physiology; Psychomotor Performance/*physiology; Vision, Ocular/*physiology  
  Abstract This study investigated temporal patterns of EMG activity during self-initiated falls with different optic flow information ('gaze directions'). Onsets of EMG during the flight phase were monitored from five experienced volunteers that completed 72 landings in three gaze directions (downward, mid-range and horizontal) and six heights of fall (10-130 cm). EMG recordings were obtained from the right gastrocnemius, tibialis anterior, biceps femoris and rectus femoris muscles, and used to determine the latency of onset (L(o)) and the perceived time to contact (T(c)). Impacts at touchdown were also monitored using as estimates the major peak of the vertical ground reaction forces (F(max)) normalized to body mass, time to peak (T(max)), peak impulse (I(norm)) normalized to momentum, and rate of change of force (dF(max)/dt). Results showed that L(o) was longer as heights of fall increased, but remained within a narrow time-window at >50 cm landings. No significant differences in L(o) were observed when gaze direction was changed. The relationship between T(c) and flight time followed a linear trend regardless of gaze direction. Gaze direction did not significantly affect the landing impacts. In conclusion, availability of optic flow during landing does not play a major role in triggering the preparatory muscle actions in self-initiated falls. Once a structured landing plan has been acquired, the relevant muscles respond relative to the start of the fall.  
  Address Department of Physical Therapy, Sackler Faculty of Medicine, Stanley Steyer School of Health Professions, University of Tel Aviv, Ramat Aviv, 69978 Tel Aviv, Israel  
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  Series Volume Series Issue Edition  
  ISSN 1050-6411 ISBN Medium  
  Area Expedition Conference  
  Notes (up) PMID:15642660 Approved no  
  Call Number Serial 39  
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Author Liebermann, D.G.; Buchman, A.S.; Franks, I.M. url  doi
openurl 
  Title Enhancement of motor rehabilitation through the use of information technologies Type Journal Article
  Year 2006 Publication Clinical Biomechanics (Bristol, Avon) Abbreviated Journal Clin Biomech (Bristol, Avon)  
  Volume 21 Issue 1 Pages 8-20  
  Keywords Biotechnology/*methods; Humans; Medical Informatics/*methods; Motion Therapy, Continuous Passive/*methods; Movement Disorders/*rehabilitation; Musculoskeletal Manipulations/methods; Rehabilitation/*methods; Robotics/*methods; Therapy, Computer-Assisted/*methods  
  Abstract The recent development of information technologies has dramatically increased the tools available for facilitating motor rehabilitation. This review focuses on technologies which can be used to augment movement-related information both to patients as well as to their therapists. A brief outline of the motor system emphasizes the role of spinal motor neurons in the control of voluntary movement and rehabilitative efforts. Technologies which induce passive motion to stimulate spinal motor output as well as technologies that stimulate active voluntary movements are discussed. Finally, we review technologies and notational methods that can be used to quantify and assess the quality of movement for evaluating the efficacy of motor rehabilitation efforts. We conclude that stronger evidence is necessary to determine the applicability of the wide range of technologies now available to clinical rehabilitation efforts.  
  Address Department of Physical Therapy, Sackler Faculty of Medicine, University of Tel Aviv, Israel. dlieberm@post.tau.ac.il  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0268-0033 ISBN Medium  
  Area Expedition Conference  
  Notes (up) PMID:16198463 Approved no  
  Call Number Serial 49  
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