Abnormal reliance on object structure in apraxics' learning of novel object-related actions.

We assessed the prediction that object structural cues could benefit the learning of object-action relationships in ideomotor apraxia (IMA). A total of 15 patients with left-hemisphere stroke, 11 of whom exhibited IMA, and 10 healthy subjects were trained to match novel gestures to novel tool pictures that were either High- or Low-Afforded by their associated tools. Learning was assessed with recognition and production tests.

Deficits in movement planning and intrinsic coordinate control in ideomotor apraxia.

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.