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The ability to predict and anticipate the mechanical demands of the environment promotes smooth and skillful motor actions. Thus, the finger forces produced to grasp and lift an object are scaled to the physical properties such as weight. While grip force scaling is well established for neutral objects, only few studies analyzed objects known from daily(More)
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(More)
Previous work with healthy adults supports the idea that perception of the orientation of a tool's handle may automatically activate cognitive components for grasping and use. An important source of evidence for this automatic activation view comes from studies showing interference when automatically activated action representations are inconsistent with(More)
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(More)
Movement goals and task mechanics differ substantially between actual tool use and corresponding pantomimes. In addition, apraxia seems to be more severe during pantomime than during actual tool use. Comparisons of these two modes of action execution using quantitative methods of movement analyses are rare. In the present study, repetitive scooping(More)
When lifting two objects with equal weight but different size, we judge the smaller object to be heavier. This size-weight illusion has been intensively tested by the recruitment of fingertip grip forces during precision lifting. Previous findings have suggested that perceptual (object size) prediction can influence sensorimotor prediction (anticipatory(More)
The scaling of our finger forces according to the properties of manipulated objects is an elementary prerequisite of skilled motor behavior. Lesions of the motor-dominant left brain may impair several aspects of motor planning. For example, limb-apraxia, a tool-use disorder after left brain damage is thought to be caused by deficient recall or integration(More)
The main goal of the study was to investigate whether the presence of affordances, such as physical properties of given objects and resulting movement constraints, induce a performance increase in actual tool-use compared to demonstrating it with only the tool or pantomiming it without the tool and recipient object. In the present study the perception of(More)
The prediction of object weight from its size is an important prerequisite of skillful object manipulation. Grip and load forces anticipate object size during early phases of lifting an object. A mismatch between predicted and actual weight when two different sized objects have the same weight results in the size-weight illusion (SWI), the small object(More)
Studying the characteristics of movements performed under different action conditions may foster the understanding of disturbed tool use in apraxia and may enhance the knowledge about the links between states of action representations. We registered hand and arm movements during a hammering action executed under three task conditions: pantomime,(More)