The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
Stephanie K Daniels - One of the best experts on this subject based on the ideXlab platform.
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swallowing apraxia a disorder of the Praxis System
Dysphagia, 2000Co-Authors: Stephanie K DanielsAbstract:The purpose of this review is to evaluate the disorder of swallowing apraxia and determine how it fits into the Praxis System. Swallowing apraxia, a proposed disorder of lingual, labial, and mandibular coordination, has been observed before bolus transfer during the oral stage of swallowing. Although frequently discussed anecdotally in dysphagia literature, the possible mechanisms and neural networks of swallowing apraxia have not been elucidated. Similarities and differences of swallowing apraxia with buccofacial, speech, and limb apraxias are evident. Critical review of the literature has identified possible similarities as greater occurrence upon command, transitive nature of the action, and evidence of spatial errors. Conversely, differences such as hemispheric lateralization and multiple gesture assessment may exist between swallowing apraxia and more traditional forms of apraxia. Until discrete error patterns of swallowing apraxia are identified and precisely measured, the nature of this disorder and its relationship with the Praxis System will continue to remain elusive.
Howard Poizner - One of the best experts on this subject based on the ideXlab platform.
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progressive ideomotor apraxia evidence for a selective impairment of the action production System
Brain and Cognition, 1995Co-Authors: Steven Z. Rapcsak, Cynthia Ochipa, Kathleen C Anderson, Howard PoiznerAbstract:Abstract We report a patient with slowly progressive bilateral limb apraxial associated with an asymmetrical focal degenerative process of the parietal lobes. Clinical assessment of Praxis production suggested a striking deficit in controlling the spatiotemporal attributes of purposeful skilled limb movements, consistent with ideomotor apraxia. The precise nature of the action production impairment was further defined by objective three-dimensional computergraphic analysis of transitive movements which demonstrated significant kinematic deficits in spatial accuracy, timing, spatiotemporal coupling, and joint coordination. Gesture comprehension and discrimination were spared. Furthermore, detailed evaluation of the conceptual Praxis System revealed that despite an almost complete inability to perform transitive movements accurately, abstract knowledge of tool function and action was remarkably well preserved. The critical dissociation between intact conceptual knowledge of action and impaired movement execution documented in this case points to a fundamental competence/performance dichotomy in apraxia and provides empirical support for cognitive models of Praxis that divide the action System into distinct conceptual and production subcomponents. Within this theoretical framework, our patients severe ideomotor apraxia is interpreted to represent a selective disruption of the action production System.
David J. Libon - One of the best experts on this subject based on the ideXlab platform.
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the role of the dynamic body schema in Praxis evidence from primary progressive apraxia
Brain and Cognition, 2000Co-Authors: Laurel J Buxbaum, Tania Giovannetti, David J. LibonAbstract:Abstract On an influential model of limb Praxis, ideomotor apraxia results from damage to stored gesture representations or disconnection of representations from sensory input or motor output (Heilman & Gonzalez Rothi, 1993; Gonzalez Rothi et al., 1991). We report data from a patient with progressive ideomotor limb apraxia which cannot be readily accommodated by this model. The patient, BG, is profoundly impaired in gesturing to command, to sight of object, and to imitation, but gestures nearly normally with tool in hand and recognizes gestures relatively well. In addition, performance is profoundly impaired on imitation of meaningless gestures and on tasks requiring spatiomotor transformations of body-position information. We provide evidence that BG's apraxia is largely attributable to impairments external to the stored gesture System in procedures coding the dynamic positions of the body parts of self and others; that is, the body schema. We propose a model of a dynamic, interactive Praxis System subserved by posterior parietal cortex in which stored representational elements, when present, provide “top-down” support to spatiomotor procedures computed on-line. In addition to accounting for BG's performance, this model accommodates a common pattern of ideomotor apraxia more readily than competing accounts.
Steven Z. Rapcsak - One of the best experts on this subject based on the ideXlab platform.
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progressive ideomotor apraxia evidence for a selective impairment of the action production System
Brain and Cognition, 1995Co-Authors: Steven Z. Rapcsak, Cynthia Ochipa, Kathleen C Anderson, Howard PoiznerAbstract:Abstract We report a patient with slowly progressive bilateral limb apraxial associated with an asymmetrical focal degenerative process of the parietal lobes. Clinical assessment of Praxis production suggested a striking deficit in controlling the spatiotemporal attributes of purposeful skilled limb movements, consistent with ideomotor apraxia. The precise nature of the action production impairment was further defined by objective three-dimensional computergraphic analysis of transitive movements which demonstrated significant kinematic deficits in spatial accuracy, timing, spatiotemporal coupling, and joint coordination. Gesture comprehension and discrimination were spared. Furthermore, detailed evaluation of the conceptual Praxis System revealed that despite an almost complete inability to perform transitive movements accurately, abstract knowledge of tool function and action was remarkably well preserved. The critical dissociation between intact conceptual knowledge of action and impaired movement execution documented in this case points to a fundamental competence/performance dichotomy in apraxia and provides empirical support for cognitive models of Praxis that divide the action System into distinct conceptual and production subcomponents. Within this theoretical framework, our patients severe ideomotor apraxia is interpreted to represent a selective disruption of the action production System.
Laurel J Buxbaum - One of the best experts on this subject based on the ideXlab platform.
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the role of the dynamic body schema in Praxis evidence from primary progressive apraxia
Brain and Cognition, 2000Co-Authors: Laurel J Buxbaum, Tania Giovannetti, David J. LibonAbstract:Abstract On an influential model of limb Praxis, ideomotor apraxia results from damage to stored gesture representations or disconnection of representations from sensory input or motor output (Heilman & Gonzalez Rothi, 1993; Gonzalez Rothi et al., 1991). We report data from a patient with progressive ideomotor limb apraxia which cannot be readily accommodated by this model. The patient, BG, is profoundly impaired in gesturing to command, to sight of object, and to imitation, but gestures nearly normally with tool in hand and recognizes gestures relatively well. In addition, performance is profoundly impaired on imitation of meaningless gestures and on tasks requiring spatiomotor transformations of body-position information. We provide evidence that BG's apraxia is largely attributable to impairments external to the stored gesture System in procedures coding the dynamic positions of the body parts of self and others; that is, the body schema. We propose a model of a dynamic, interactive Praxis System subserved by posterior parietal cortex in which stored representational elements, when present, provide “top-down” support to spatiomotor procedures computed on-line. In addition to accounting for BG's performance, this model accommodates a common pattern of ideomotor apraxia more readily than competing accounts.