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Query: UMLS:C0003635 (apraxia)
 2,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In patients with apraxia the ability to access tool-use-knowledge and to integrate it into a movement plan is frequently disturbed. The present study investigated potential differences between a 'transport'- and a 'use'-task as well as the influence of apraxia on the preceding grasping movement, when the tool is presented with its handle pointing away from the participant. 20 controls, 10 patients with right brain damage (RBD-group) and 17 patients with left brain damage (LBD-group) were tested. 10 LBD-patients were classified as moderately to severely apraxic according to erroneous demonstration of tool-use. Participants were asked to grasp the tool and either to demonstrate its typical 'use' or to 'transport' it into a container. Functional grasp, which enables comfortable use, was distinguished from non-functional grasp. The results showed that task-content influences the way to grasp an object. Apart from some LBD-patients, nearly all participants produced 100% functional grasps during the 'use'-task. Additionally inappropriate non-functional grasping has always been followed by apraxic tool-use behaviour. Compared to the 'use'-task in the 'transport'-task, functional grasping was significantly reduced in all groups. Our results imply that grasping a tool is specific to a task. Selection of the grasp type seems to be determined by individual weighting of several factors, including knowledge about the function of the object, structural tool characteristics, biomechanical costs of the movement, and previous experience. In general perception and integration of tool-structure plus specific tool-related functional knowledge are necessary for its use and might be processed synchronously. Patients with apraxic tool-use may fail to access any of these information resources.
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PMID:Grasping tools: effects of task and apraxia. 1897 35

Tool use engages a left hemispheric network including frontal, temporal and parietal regions. Patients with left brain lesions (LBD patients) exhibit deficits when demonstrating use of a single tool (apraxia). When attempting to use a tool, some apraxic patients show errors in the preceding grasping movement. Forty-two LBD patients and 18 healthy controls grasped individual tools and demonstrated their typical use. For patients with a tool use impairment (22), lesion analysis revealed a large area of overlap in the left hemisphere, mainly in the supramarginal gyrus (SMG). For patients with erroneous grasping (12), the lesion overlay showed overlaps in the left frontal and parietal cortices, especially in the inferior frontal gyrus (IFG) and the angular gyrus (ANG). However, contrasting lesions associated with impaired grasping versus tool use impairments reveal little overlap, limited to the inferior parietal cortex. Presumably the left IFG is involved in selection processes in the context of tool use, such as choosing a functional or non-functional grasping movement depending on the task and the online information about the tool's structure and orientation. The ANG might provide this grasp related information, which is relevant for the specific action. The contribution of the SMG to tool use involves more general principals, such as integrating online and learned tool use information into the action plan for the use movement.
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PMID:Different left brain regions are essential for grasping a tool compared with its subsequent use. 2060 Sep 86