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Rosenbaum DA, Cohen RG, Jax SA, Weiss DJ, van der Wel R. The problem of serial order in behavior: Lashley’s legacy. Hum Mov Sci 2007; 26:525-54. [PMID: 17698232 DOI: 10.1016/j.humov.2007.04.001] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In a prescient paper Karl Lashley (1951) rejected reflex chaining accounts of the sequencing of behavior and argued instead for a more cognitive account in which behavioral sequences are typically controlled with central plans. An important feature of such plans, according to Lashley, is that they are hierarchical. Lashley offered several sources of evidence for the hierarchical organization for behavioral plans, and others afterward provided more evidence for this hypothesis. We briefly review that evidence here and then shift from a focus on the structure of plans (Lashley's point of concentration) to the processes by which plans are formed in real time. Two principles emerge from the studies we review. One is that plans are not formed from scratch for each successive movement sequence but instead are formed by making whatever changes are needed to distinguish the movement sequence to be performed next from the movement sequence that has just been performed. This plan-modification view is supported by two phenomena discovered in our laboratory: the parameter remapping effect, and the handpath priming effect. The other principle we review is that even single movements appear to be controlled with hierarchically organized plans. At the top level are the starting and goal postures. At the lower level are the intermediate states comprising the transition from the starting posture to the goal posture. The latter principle is supported by another phenomenon discovered in our lab, the end-state comfort effect, and by a computational model of motor planning which accounts for a large number of motor phenomena. Interestingly, the computational model hearkens back to a classical method of generating cartoon animations that relies on the production of keyframes first and the production of interframes (intermediate frames) second.
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18 |
135 |
2
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Jax SA, Rosenbaum DA. Hand path priming in manual obstacle avoidance: evidence that the dorsal stream does not only control visually guided actions in real time. J Exp Psychol Hum Percept Perform 2007; 33:425-41. [PMID: 17469977 DOI: 10.1037/0096-1523.33.2.425] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
According to a prominent theory of human perception and performance (M. A. Goodale & A. D. Milner, 1992), the dorsal, action-related stream only controls visually guided actions in real time. Such a system would be predicted to show little or no action priming from previous experience. The 3 experiments reported here were designed to determine whether priming exists for visually guiding the hand to targets with obstacles sometimes in the way. In all 3 experiments, priming was observed in the curvature of hand paths. Hand paths when no obstacles were present were more curved if obstacles had recently appeared than if obstacles had not recently appeared. The results also show that hand path priming was not the result of active prediction, persisted for many trials, and generalized over the workspace. The times to initiate movements also reflected the use of a sophisticated visual search strategy that took obstacle likelihood into account.
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Research Support, U.S. Gov't, Non-P.H.S. |
18 |
87 |
3
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Jax SA, Buxbaum LJ. Response interference between functional and structural actions linked to the same familiar object. Cognition 2010; 115:350-5. [PMID: 20156619 DOI: 10.1016/j.cognition.2010.01.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 12/03/2009] [Accepted: 01/14/2010] [Indexed: 11/19/2022]
Abstract
Viewing objects with the intention to act upon them may activate task-irrelevant motor responses. Many manufactured objects are associated with two action classes: grasping in accordance with object structure and skillful use consistent with object function. We studied the potential for within-object competition during action selection by comparing initiation latencies for "conflict" objects (with competing structure and function responses) to "non-conflict" objects (with a single response). We demonstrated a novel pattern of within-object interference wherein actions involving conflict objects were slowed when participants skillfully used those objects (grasp-on-use interference) as well as a second pattern of interference when conflict objects were grasped after skillfully using the same objects in previous blocks (long-term use-on-grasp interference). These data suggest that actions to common objects are influenced by competition between rapid but briefly maintained grasp responses and slower but longer-lasting use responses, and advance our understanding of the process and neural substrates of selection for action.
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Research Support, N.I.H., Extramural |
15 |
80 |
4
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Bark K, Hyman E, Tan F, Cha E, Jax SA, Buxbaum LJ, Kuchenbecker KJ. Effects of vibrotactile feedback on human learning of arm motions. IEEE Trans Neural Syst Rehabil Eng 2014; 23:51-63. [PMID: 25486644 DOI: 10.1109/tnsre.2014.2327229] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Tactile cues generated from lightweight, wearable actuators can help users learn new motions by providing immediate feedback on when and how to correct their movements. We present a vibrotactile motion guidance system that measures arm motions and provides vibration feedback when the user deviates from a desired trajectory. A study was conducted to test the effects of vibrotactile guidance on a subject's ability to learn arm motions. Twenty-six subjects learned motions of varying difficulty with both visual (V), and visual and vibrotactile (VVT) feedback over the course of four days of training. After four days of rest, subjects returned to perform the motions from memory with no feedback. We found that augmenting visual feedback with vibrotactile feedback helped subjects reduce the root mean square (rms) angle error of their limb significantly while they were learning the motions, particularly for 1DOF motions. Analysis of the retention data showed no significant difference in rms angle errors between feedback conditions.
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Research Support, U.S. Gov't, Non-P.H.S. |
11 |
77 |
5
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Kantak S, Jax S, Wittenberg G. Bimanual coordination: A missing piece of arm rehabilitation after stroke. Restor Neurol Neurosci 2018; 35:347-364. [PMID: 28697575 DOI: 10.3233/rnn-170737] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Inability to use the arm in daily actions significantly lowers quality of life after stroke. Most contemporary post-stroke arm rehabilitation strategies that aspire to re-engage the weaker arm in functional activities have been greatly limited in their effectiveness. Most actions of daily life engage the two arms in a highly coordinated manner. In contrast, most rehabilitation approaches predominantly focus on restitution of the impairments and unilateral practice of the weaker hand alone. We present a perspective that this misalignment between real world requirements and intervention strategies may limit the transfer of unimanual capability to spontaneous arm use and functional recovery. We propose that if improving spontaneous engagement and use of the weaker arm in real life is the goal, arm rehabilitation research and treatment need to address the coordinated interaction between arms in targeted theory-guided interventions. Current narrow focus on unimanual deficits alone, difficulty in quantifying bimanual coordination in real-world actions and limited theory-guided focus on control and remediation of different coordination modes are some of the biggest obstacles to successful implementation of effective interventions to improve bimanual coordination in the real world. We present a theory-guided taxonomy of bimanual actions that will facilitate quantification of coordination for different real-world tasks and provide treatment targets for addressing coordination deficits. We then present evidence in the literature that points to bimanual coordination deficits in stroke survivors and demonstrate how current rehabilitation approaches are limited in their impact on bimanual coordination. Importantly, we suggest theory-based areas of future investigation that may assist quantification, identification of neural mechanisms and scientifically-based training/remediation approaches for bimanual coordination deficits post-stroke. Advancing the science and practice of arm rehabilitation to incorporate bimanual coordination will lead to a more complete functional recovery of the weaker arm, thus improving the effectiveness of rehabilitation interventions and augmenting quality of life after stroke.
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Review |
7 |
51 |
6
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Jax SA, Buxbaum LJ, Moll AD. Deficits in movement planning and intrinsic coordinate control in ideomotor apraxia. J Cogn Neurosci 2007; 18:2063-76. [PMID: 17129191 DOI: 10.1162/jocn.2006.18.12.2063] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Two central issues in the field of motor control are the coordinate frame in which movements are controlled and the distinction between movement planning and online correction. In this study we used these issues to frame several hypotheses about the deficits underlying ideomotor apraxia (IMA). In particular, we examined whether ideomotor apraxics exhibited (1) deficits in movement control in intrinsic (body relative) coordinates with better control in extrinsic (workspace relative) coordinates, (2) deficits in movement planning that are compensated for by an overreliance on online correction, or (3) both deficits. Patients with IMA and two comparison groups performed movement tasks that relied preferentially on either intrinsic or extrinsic coordinate control when online correction was either possible or impossible. Participants performed posture imitation and grasp imitation movements to body- and object-relative end positions in the presence or absence of visual feedback. Consistent with the intrinsic coordinate control hypothesis, patients with IMA showed a significantly greater disparity than the other two groups between movements made to body-relative and object-relative targets as well as between imitation of meaningless postures and grasping. Consistent with the correction overreliance hypothesis, the IMA group was more disrupted than the other groups by the removal of vision. Thus, IMA patients exhibit behavioral patterns consistent with both deficient intrinsic coordinate control and overreliance upon visual feedback. Finally, lesion analysis suggests that damage to the left inferior parietal lobe (Brodmann's areas 39 and 40) may play a key role in both behavioral deficits.
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Research Support, U.S. Gov't, Non-P.H.S. |
18 |
45 |
7
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van der Wel RPRD, Fleckenstein RM, Jax SA, Rosenbaum DA. Hand path priming in manual obstacle avoidance: evidence for abstract spatiotemporal forms in human motor control. J Exp Psychol Hum Percept Perform 2008; 33:1117-26. [PMID: 17924811 DOI: 10.1037/0096-1523.33.5.1117] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previous research suggests that motor equivalence is achieved through reliance on effector-independent spatiotemporal forms. Here the authors report a series of experiments investigating the role of such forms in the production of movement sequences. Participants were asked to complete series of arm movements in time with a metronome and, on some trials, with an obstacle between 1 or more of the target pairs. In moves following an obstacle, participants only gradually reduced the peak heights of their manual jumping movements. This hand path priming effect, scaled with obstacle height, was preserved when participants cleared the obstacle with 1 hand and continued with the other, and it was modulated by future task demands. The results are consistent with the hypothesis that the control of movement sequences relies on abstract spatiotemporal forms. The data also support the view that motor programming is largely achieved by changing just those features that distinguish the next movement to be made from the movement that was just made.
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Research Support, U.S. Gov't, Non-P.H.S. |
17 |
44 |
8
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Jax SA, Rosenbaum DA. Hand path priming in manual obstacle avoidance: rapid decay of dorsal stream information. Neuropsychologia 2008; 47:1573-7. [PMID: 18597796 DOI: 10.1016/j.neuropsychologia.2008.05.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 04/11/2008] [Accepted: 05/20/2008] [Indexed: 10/22/2022]
Abstract
The dorsal, action-related, visual stream has been thought to have little or no memory. This hypothesis has seemed credible because functions related to the dorsal stream have been generally unsusceptible to priming from previous experience. Tests of this claim have yielded inconsistent results, however. We argue that these inconsistencies may be due to methodological differences in the time between primes and test stimuli. In this study we sought to clarify the effect of time between primes and test stimuli by having participants complete a visually guided manual obstacle avoidance task with varying times between trials. Consistent with a previous study using this task, we found that hand path curvature depended on the presence or absence of an obstacle in the previous trial. This hand path priming effect decayed quickly as the time between trials increased, and was almost, though not entirely, eliminated when 1000 ms separated successive trials. The results are consistent with the hypothesis that the dorsal stream can be primed but that this priming attenuates rapidly. We suggest that this outcome may indicate that the period over which the dorsal stream retains information may be related to the sequential statistics of action.
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Research Support, U.S. Gov't, Non-P.H.S. |
17 |
40 |
9
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Botvinick MM, Buxbaum LJ, Bylsma LM, Jax SA. Toward an integrated account of object and action selection: a computational analysis and empirical findings from reaching-to-grasp and tool-use. Neuropsychologia 2008; 47:671-83. [PMID: 19100758 DOI: 10.1016/j.neuropsychologia.2008.11.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 11/04/2008] [Accepted: 11/20/2008] [Indexed: 11/19/2022]
Abstract
The act of reaching for and acting upon an object involves two forms of selection: selection of the object as a target, and selection of the action to be performed. While these two forms of selection are logically dissociable, and are evidently subserved by separable neural pathways, they must also be closely coordinated. We examine the nature of this coordination by developing and analyzing a computational model of object and action selection first proposed by Ward [Ward, R. (1999). Interactions between perception and action systems: a model for selective action. In G. W. Humphreys, J. Duncan, & A. Treisman (Eds.), Attention, Space and Action: Studies in Cognitive Neuroscience. Oxford: Oxford University Press]. An interesting tenet of this account, which we explore in detail, is that the interplay between object and action selection depends critically on top-down inputs representing the current task set or plan of action. A concrete manifestation of this, established through a series of simulations, is that the impact of distractor objects on reaching times can vary depending on the nature of the current action plan. In order to test the model's predictions in this regard, we conducted two experiments, one involving direct object manipulation, the other involving tool-use. In both experiments we observed the specific interaction between task set and distractor type predicted by the model. Our findings provide support for the computational model, and more broadly for an interactive account of object and action selection.
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Research Support, N.I.H., Extramural |
17 |
29 |
10
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Medina J, Jax SA, Coslett HB. Two-component models of reaching: evidence from deafferentation in a Fitts' law task. Neurosci Lett 2009; 451:222-6. [PMID: 19150390 DOI: 10.1016/j.neulet.2009.01.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 12/17/2008] [Accepted: 01/04/2009] [Indexed: 11/28/2022]
Abstract
Both feedforward and feedback mechanisms are used to ensure accurate movements. Feedback information comes primarily from vision and proprioception; the relative contributions of these modalities to on-line control of action and internal model maintenance remain unclear. We report data from an experiment in which a chronically deafferented subject (JDY) and nine controls were asked to reach to targets of different sizes both with and without vision. Movement times of controls were consistent with Fitts' law on trials with and without vision. JDY's movement times were consistent with Fitts' law only with vision. She was inaccurate relative to controls with vision but exhibited a significantly greater decrement in performance than controls without vision. Finally, JDY's performance on trials with vision deteriorated as a function of the number of preceding trials on which vision was not available. These data provide support for classical models of motor control that divide reaching into an initial ballistic movement guided by efference copy, and a terminal stage where sensory feedback is crucial. Furthermore, these data also demonstrate that proprioception is needed to calibrate and maintain internal models of action.
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Research Support, N.I.H., Extramural |
16 |
23 |
11
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Jax SA, Buxbaum LJ. Response interference between functional and structural object-related actions is increased in patients with ideomotor apraxia. J Neuropsychol 2012; 7:12-8. [PMID: 22515637 DOI: 10.1111/j.1748-6653.2012.02031.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report data from two left hemisphere stroke patients with moderate-to-severe ideomotor apraxia who exhibited deficits in positioning their hands to use 'conflict' objects (objects grasped and used with different hand postures) relative to controls and patients with mild apraxia. These novel data support the claim that actions to common objects are subject to interference between multiple responses, and suggest that errors in apraxia may be attributed to deficient resolution of competition between appropriate and inappropriate actions.
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Research Support, Non-U.S. Gov't |
13 |
22 |
12
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Rosenbaum DA, Cohen RG, Dawson AM, Jax SA, Meulenbroek RG, van der Wel R, Vaughan J. The posture-based motion planning framework: new findings related to object manipulation, moving around obstacles, moving in three spatial dimensions, and haptic tracking. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 629:485-97. [PMID: 19227517 DOI: 10.1007/978-0-387-77064-2_26] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
We describe the results of recent studies inspired by the posture-based motion planning theory (Rosenbaum et al., 2001). The research concerns analyses of human object manipulation, obstacle avoidance, three-dimensional movement generation, and haptic tracking, the findings of which are discussed in relation to whether they support or fail to support the premises of the theory. Each of the aforementioned topics potentially challenges the theory's claim that, in motion, goal postures are planned before the selection of movements towards those postures. However, even the quasi-continuous phenomena under study show features that comply with prospective, end-state-based motion planning. We conclude that progress in motor control should not be frustrated by the view that no model is, or will ever be, optimal. Instead, it should find promise in the steady growth of insights afforded by challenges to existing theories.
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Research Support, N.I.H., Extramural |
16 |
18 |
13
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Tsagkaridis K, Watson CE, Jax SA, Buxbaum LJ. The role of action representations in thematic object relations. Front Hum Neurosci 2014; 8:140. [PMID: 24672461 PMCID: PMC3957493 DOI: 10.3389/fnhum.2014.00140] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 02/25/2014] [Indexed: 11/13/2022] Open
Abstract
A number of studies have explored the role of associative/event-based (thematic) and categorical (taxonomic) relations in the organization of object representations. Recent evidence suggests that thematic information may be particularly important in determining relationships between manipulable artifacts. However, although sensorimotor information is on many accounts an important component of manipulable artifact representations, little is known about the role that action may play during the processing of semantic relationships (particularly thematic relationships) between multiple objects. In this study, we assessed healthy and left hemisphere stroke participants to explore three questions relevant to object relationship processing. First, we assessed whether participants tended to favor thematic relations including action (Th+A, e.g., wine bottle-corkscrew), thematic relationships without action (Th-A, e.g., wine bottle-cheese), or taxonomic relationships (Tax, e.g., wine bottle-water bottle) when choosing between them in an association judgment task with manipulable artifacts. Second, we assessed whether the underlying constructs of event relatedness, action relatedness, and categorical relatedness determined the choices that participants made. Third, we assessed the hypothesis that degraded action knowledge and/or damage to temporo-parietal cortex, a region of the brain associated with the representation of action knowledge, would reduce the influence of action on the choice task. Experiment 1 showed that explicit ratings of event, action, and categorical relatedness were differentially predictive of healthy participants' choices, with action relatedness determining choices between Th+A and Th-A associations above and beyond event and categorical ratings. Experiment 2 focused more specifically on these Th+A vs. Th-A choices and demonstrated that participants with left temporo-parietal lesions, a brain region known to be involved in sensorimotor processing, were less likely than controls and tended to be less likely than patients with lesions sparing that region to use action relatedness in determining their choices. These data indicate that action knowledge plays a critical role in processing of thematic relations for manipulable artifacts.
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research-article |
11 |
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14
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Wong AL, Jax SA, Smith LL, Buxbaum LJ, Krakauer JW. Movement Imitation via an Abstract Trajectory Representation in Dorsal Premotor Cortex. J Neurosci 2019; 39:3320-3331. [PMID: 30804087 PMCID: PMC6788821 DOI: 10.1523/jneurosci.2597-18.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/09/2019] [Accepted: 02/19/2019] [Indexed: 01/08/2023] Open
Abstract
Humans are particularly good at copying novel and meaningless gestures. The mechanistic and anatomical basis for this specialized imitation ability remains largely unknown. One idea is that imitation occurs by matching body configurations. Here we propose an alternative route to imitation that depends on a body-independent representation of the trajectory path of the end-effector. We studied a group of patients with strokes in the left frontoparietal cortices. We found that they were equally impaired at imitating movement trajectories using the ipsilesional limb (i.e., the nonparetic side) that were cued either by an actor using their whole arm or just by a cursor, suggesting that body configuration information is not always critical for imitation and that a representation of abstract trajectory shape may suffice. In addition, imitation ability was uncorrelated to the ability to identify the trajectory shape, suggesting that imitation deficits were unlikely to arise from perceptual impairments. Finally, a lesion-symptom mapping analysis found that imitation deficits were associated with lesions in left dorsal premotor but not parietal cortex. Together, these findings suggest a novel body-independent route to imitation that relies on the ability to plan abstract movement trajectories within dorsal premotor cortex.SIGNIFICANCE STATEMENT The ability to imitate is critical for rapidly learning to produce new gestures and actions, but how the brain translates observed movements into motor commands is poorly understood. Examining the ability of patients with strokes affecting the left hemisphere revealed that meaningless gestures can be imitated by succinctly representing only the motion of the hand in space, rather than the posture of the entire arm. Moreover, performance deficits correlated with lesions in dorsal premotor cortex, an area not previously associated with impaired imitation of arm postures. These findings thus describe a novel route to imitation that may also be impaired in some patients with apraxia.
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Research Support, N.I.H., Extramural |
6 |
17 |
15
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Jax SA, Rosenbaum DA, Vaughan J. Extending Fitts’ Law to manual obstacle avoidance. Exp Brain Res 2007; 180:775-9. [PMID: 17562027 DOI: 10.1007/s00221-007-0996-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Accepted: 05/16/2007] [Indexed: 10/23/2022]
Abstract
In this study we asked whether Fitts' Law, a well-established relationship that predicts movement times (MTs) for direct movements between two positions, could be extended to predict MTs for curved, obstacle avoiding, movements. We had participants make movements in the presence of an obstacle. Using these data, we tested an extensions of Fitts' Law that predicted MTs based on the movement's index of difficulty and the distance that the obstacle intruded into the direct movement path. Including both factors led to more accurate predictions of MTs for obstacle-avoiding movements than was possible with the index of difficulty alone. In addition, the simple extension of Fitts' Law did as well as a model which relied on the obtained movement paths between targets. This is an encouraging outcome because it suggests that the physical layout of the workspace can be used to predict MTs for obstacle avoiding movements, an accomplishment that fits with the spirit of Fitts' Law.
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16
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Medina J, Jax SA, Brown MJ, Coslett HB. Contributions of efference copy to limb localization: evidence from deafferentation. Brain Res 2010; 1355:104-11. [PMID: 20659430 DOI: 10.1016/j.brainres.2010.07.063] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Revised: 07/08/2010] [Accepted: 07/18/2010] [Indexed: 10/19/2022]
Abstract
Previous research with deafferented subjects suggests that efference copy can be used to update limb position. However, the contributions of efference copy to limb localization are currently unclear. We examined the performance of JDY, a woman with severe, longstanding proprioceptive deficits from a sensory peripheral neuropathy, on a reaching task to explore the contribution of efference copy to trajectory control. JDY and eight healthy controls reached without visual feedback to a target that either remained stationary or jumped to a second location after movement initiation. JDY consistently made hypermetric movements to the final target, exhibiting significant problems with amplitude control. Despite this amplitude control deficit, JDY's performance on jump trials showed that the angle of movement correction (angle between pre- and post-correction movement segments) was significantly correlated with the distance (but not time) of movement from start to turn point. These data suggest that despite an absence of proprioceptive and visual information regarding hand location, JDY derived information about movement distance that informed her movement correction on jump trials. The same type of information that permitted her to correct movement direction on-line, however, was not available for control of final arm position. We propose that efference copy can provide a consistent estimate of limb position that becomes less informative over the course of the movement. We discuss the implications of these data for current models of motor control.
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Journal Article |
15 |
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17
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Jax SA, Rosenbaum DA, Vaughan J, Meulenbroek RGJ. Computational motor control and human factors: modeling movements in real and possible environments. HUMAN FACTORS 2003; 45:5-27. [PMID: 12916579 DOI: 10.1518/hfes.45.1.5.27226] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
An aim of human factors research is to have models that allow for the advance design of user-friendly environments. This is still a distant dream because existing models are not yet sufficiently sophisticated. Models in the domain of motor control are a case in point, but recent developments in computational motor control suggest that the gap between the current state of modeling in this area and the desired state is shrinking. To illustrate this point, we review principles of motor control research that any model of motor control must accommodate. Then we describe a model that captures many of the capacities of actors in the everyday world, including the capacity to reach for objects in different ways depending on factors such as the ease with which different joints can rotate, the required speed of movement, and whether obstacles are present. The model relies on the ideas that goal postures are internally specified before movements are generated, that tasks are defined with flexibly ordered constraint hierarchies, and that movements can be shaped according to task demands. Actual or potential applications of this research include designing and testing possible environments where motor components play a key role.
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Review |
22 |
14 |
18
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Jax SA, Buxbaum LJ, Lie E, Coslett HB. More than (where the target) meets the eyes: disrupted visuomotor transformations in optic ataxia. Neuropsychologia 2008; 47:230-8. [PMID: 18725238 DOI: 10.1016/j.neuropsychologia.2008.07.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Revised: 07/24/2008] [Accepted: 07/28/2008] [Indexed: 11/27/2022]
Abstract
Visually guided reaching entails multiple coordinate frame transformations between retina-centered target location and body-centered limb location. Reaching errors in optic ataxia (OA) may be caused by disruptions to these transformations. Consistent with this proposal, previous studies report that reaching errors in OA depend primarily on the location of a target relative to the patient's gaze regardless of its location relative to the head or body midline. We attempted to replicate this finding by testing KE, a patient with OA following bilateral parietal and left premotor lesions (as well as significant non-specific white matter disease) on a reaching task that varied the orientation of his head and torso while holding the gaze-relative position of the target constant (always foveated). In contrast to previous reports, we observed that rotating the head or body away from the midline led to decreased reaching accuracy. Further analyses showed that multiple visuomotor transformation steps might have been disrupted in KE. These results suggest that gaze-relative target position is not the sole determinant of reaching errors in all OA patients.
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Research Support, U.S. Gov't, Non-P.H.S. |
17 |
12 |
19
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Jax SA, Rosa-Leyra DL, Buxbaum LJ. Conceptual- and production-related predictors of pantomimed tool use deficits in apraxia. Neuropsychologia 2014; 62:194-201. [PMID: 25107676 DOI: 10.1016/j.neuropsychologia.2014.07.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 07/01/2014] [Accepted: 07/14/2014] [Indexed: 10/24/2022]
Abstract
Apraxia following left hemisphere stroke disrupts pantomimed tool use (PTU), a task that requires the integrity of a number of cognitive and motor processes. Although previous studies have identified that apraxics have deficits in (1) the integrity of/access to stored tool-use gesture representations, (2) deficits in intrinsic (body-based) coordinate control, and (3) abnormal reliance on visual feedback, no study to date has simultaneously tested the relative contribution of these three deficits to poor PTU performance. In this study we assessed 38 chronic left hemisphere stroke survivors on tests of PTU and the 3 component processes. We then attempted to predict PTU with the component scores using hierarchical regression to control for overall stroke severity and the possibility of correlated component scores. Results showed that over half of the variability in PTU was predictable, with the strongest independent predictor being a test of intrinsic coordinate control without visual feedback. A test of the integrity of/access to stored representations also predicted PTU. These results confirm and extend previous claims that conceptual- and production-related factors affect PTU, even after considering that deficits in both factors are commonly observed to varying degrees in apraxic patients.
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Research Support, N.I.H., Extramural |
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Ambron E, Schettino LF, Coyle M, Jax S, Coslett HB. When perception trips action! The increase in the perceived size of both hand and target matters in reaching and grasping movements. Acta Psychol (Amst) 2017; 180:160-168. [PMID: 28957732 DOI: 10.1016/j.actpsy.2017.09.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 08/22/2017] [Accepted: 09/20/2017] [Indexed: 10/18/2022] Open
Abstract
Reaching and grasping movements rely on visual information regarding the target characteristics (e.g. size) and the hand position during the action execution. Changes in the visual representation of the body (e.g. increase in the perceived size of the hand) can modify action performance, but it is still unclear how these modifications interact with changes in the external environment. We investigated this topic by manipulating the perceived size of both hand and target objects and the degree of visual feedback available during the movement execution. Ten young adults were asked to reach and grasp geometrical objects in four different conditions: (i) with normal vision with the light on, (ii) with normal vision in the dark, (iii) using magnifying lenses in the light and (iv) using magnifying lenses in the dark. In contrast with previous works, our results show that movement execution is longer in magnified vision compared to normal when the action is executed in the light, but the grasping component was not affected by changes in size in this condition. On the contrary, when the visual feedback of the hand was removed and participants performed the action in the dark, movements were faster and the distances across fingers larger in the magnified than normal vision. This pattern of data suggests that grasping movements adapt rapidly and compensate for changes in vision when this process depends on the degree of visual feedback and/or environmental cues available. In the debate regarding the dissociation between action and perception, our data suggest that action may overcome changes in perception when visual feedback is available, but perception may trick action in situations of reduced visual information.
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Journal Article |
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Ambron E, Jax S, Schettino LF, Coslett HB. Magnifying vision improves motor performance in individuals with stroke. Neuropsychologia 2018; 119:373-381. [PMID: 30172830 DOI: 10.1016/j.neuropsychologia.2018.08.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/25/2018] [Accepted: 08/29/2018] [Indexed: 10/28/2022]
Abstract
Increasing perceived hand size using magnifying lenses improves tactile discrimination and motor performance in neurologically-intact individuals. We tested whether magnification of the hand can improve motor function in individuals with chronic stroke. Twenty-five individuals with a history of stroke more than 6 months prior to testing underwent a series of tasks exploring different aspects of motor performance (grip force, finger tapping, reaching and grasping, and finger matching) under two visual conditions: magnified or normal vision. Performance was also assessed shortly after visual manipulation to test if these effects persisted. Twenty-eight percent of individuals showed an immediate significant improvement averaged across all tasks with magnification; similar beneficial responses were also observed in 32% of individuals after a short delay. These results suggest that magnification of the image of the hand may be of utility in rehabilitation of individuals with stroke.
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Research Support, N.I.H., Extramural |
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Jax SA, Rosa-Leyra DL, Coslett HB. Enhancing the mirror illusion with transcranial direct current stimulation. Neuropsychologia 2015; 71:46-51. [PMID: 25796410 DOI: 10.1016/j.neuropsychologia.2015.03.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/03/2015] [Accepted: 03/17/2015] [Indexed: 11/17/2022]
Abstract
Visual feedback has a strong impact on upper-extremity movement production. One compelling example of this phenomena is the mirror illusion (MI), which has been used as a treatment for post-stroke movement deficits (mirror therapy). Previous research indicates that the MI increases primary motor cortex excitability, and this change in excitability is strongly correlated with the mirror's effects on behavioral performance of neurologically-intact controls. Based on evidence that primary motor cortex excitability can also be increased using transcranial direct current stimulation (tDCS), we tested whether bilateral tDCS to the primary motor cortices (anode right-cathode left and anode left-cathode right) would modify the MI. We measured the MI using a previously-developed task in which participants make reaching movements with the unseen arm behind a mirror while viewing the reflection of the other arm. When an offset in the positions of the two limbs relative to the mirror is introduced, reaching errors of the unseen arm are biased by the reflected arm's position. We found that active tDCS in the anode right-cathode left montage increased the magnitude of the MI relative to sham tDCS and anode left-cathode right tDCS. We take these data as a promising indication that tDCS could improve the effect of mirror therapy in patients with hemiparesis.
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Research Support, Non-U.S. Gov't |
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Ambron E, Jax S, Schettino L, Coslett HB. Increasing perceived hand size improves motor performance in individuals with stroke: a home-based training study. PeerJ 2019; 7:e7114. [PMID: 31392085 PMCID: PMC6673464 DOI: 10.7717/peerj.7114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/10/2019] [Indexed: 11/24/2022] Open
Abstract
Background Increasing perceived hand size with magnifying lenses improves tactile discrimination and induces changes in action performance. We previously demonstrated that motor skills (tested with grip force, finger tapping, and a reach to grasp tasks) improved when actions were performed with magnified compared to normal vision; twenty-eight percent of 25 participants with stroke exhibited significant improvement on a composite measure of motor performance with magnification as compared to a session without magnification. Methods To investigate the potential implications of magnification of vision for motor rehabilitation, we recruited individuals with stroke from the original cohort who exhibited an improvement of at least 10% in grip force and/or finger tapping for a home training protocol. Six individuals with stroke completed a two-week home-based training program in which they performed a range of activities while looking at their hand magnified. Motor skills were measured before, immediately after, and two weeks after the training. Results Five of the six participants showed an improvement on motor tasks when tested after the training. In two participants the improvement was evident immediately after the training and persisted in time, while it occurred at two-weeks post-training in the other participants. These results suggest that the magnification of vision is a potential tool for the rehabilitation of post-stroke motor deficits.
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Journal Article |
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Jax S. Poster 27 Benefits of Mirror-Therapy for Hemiparesis Following Stroke are Reduced With Increased Engagement of Contralesional Hemisphere. Arch Phys Med Rehabil 2012. [DOI: 10.1016/j.apmr.2012.08.061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
The mirror illusion uses a standard mirror to create a compelling illusion in which movements of one limb seem to be made by the other hidden limb. In this paper we adapt a motor control framework to examine which estimates of the body's configuration are affected by the illusion. We propose that the illusion primarily alters estimates related to upcoming states of the body (the desired state and the predicted state), with smaller effects on the estimate of the body state prior to movement initiation. Support for this proposal is provided both by behavioural effects of the illusion and by neuroimaging evidence from one neural region, V6A, that is critically involved in the mirror illusion and limb state estimation more generally.
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Review |
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