Apraxia.

UNLABELLED: The term apraxia refers to 'higher level' disorders of motor control. Apraxia differs from other motor symptoms of unilateral brain damage by the bilaterality of symptoms following unilateral lesions. Lesions causing apraxia are located predominantly in the left hemisphere and apraxia is frequently, although not invariably, associated with aphasia. Examination for apraxia traditionally assesses imitation of gestures, performance of communicative gestures on command, and use of tools and objects. It has, however, been amply demonstrated that these three domains can be affected more or less independently from each other. This review discusses current topics of research and controversy from each of these domains concentrating on questions that are relevant for determining the border between motor and cognitive mechanisms underlying apraxic errors. For imitation, the proposal of a direct link from perception to motor execution is confronted with the hypothesis that body part coding is interpolated between perception and motor replication of gestures. Discussion of communicative gestures concentrates on pantomime of tool use and argues that pantomime is not equivalent to reproduction of the motor programs of actual tool use but that pantomimes are created by selection and combination of distinctive features of the object and its use. For tool use the boundary between visuo-motor coordination and knowledge about tool use is addressed by discussion of the selection of grips for use or for transport of tools. WIREs Cogn Sci 2013, 4:453-462. doi: 10.1002/wcs.1241 For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST: The author has declared no conflicts of interest for this article.