Cognition in action: Testing a model of limb apraxia

Assessment of Limb apraxia. is still suffering from Liepmann's legacy and p erformance in gesture-processing tests is generally rendered by classifying patients' profile according to the classic clinical labels of ideomotor an d ideational apraxia. At odds with other cognitive functions, interpretatio n of apraxia has suffered from a lack of a reliable model which does justic e to its complexity. Recently such a model has been proposed (Rothi ct al., 1991, 1997). in this article a modified version of this model is presented and predictions are made according to its functional architecture. Five di fferent patterns of impairment of gesture processing are postulated. To val idate the predicted performance profiles, 19 left-hemisphere-damaged patien ts ware assessed by means of an ad hoc battery of four praxis tests, Four o f the five predicted apraxia patterns were observed, the fifth being more e quivocal, These results support the need to overcome the simplistic dichoto mous view of apraxia and confirm the fruitfulness of a model of normal gest ure processing in order to understand dissociations in apraxia. (C) 2000 Ac ademic Press.