Analysis of a disorder of everyday action

Abstract

Abstract We present a patient, JK, who developed a profound disturbance of routine action production subsequent to closed head injury. Part I of the study describes the disorder as it was expressed in tasks of everyday living. JK demonstrated the features of frontal apraxia, including extreme vulnerability to object substitution and object misuse. In Part II we carried out a neuro-psychological assessment targeted at JK's recognition and understanding of objects and implements. This assessment showed a surprising preservation of low- and high-level vision, as well as semantic knowledge relevant to everyday tasks. It also revealed some areas of weakness, notably in access to semantic memory and gesture recall. It is widely accepted that everyday action tasks are planned and executed automatically, that is, with minimal involvement of executive control processes. JK's defects in the areas of semantic memory and gesture recall may have compromised the automaticity of his action planning, but this alone cannot account for his flagrant everyday-action disorder. We speculate, without direct evidence, that the executive control processes (supervisory attention/working memory) that support non-automatic action planning might also have been compromised in JK. If so, it suggests a new account of frontal apraxia, which rests on a combination of deficits: (1) disruption of the fast, automatic retrieval of information from memory stores relevant to action planning; and (2) pathological depletion of executive resources necessary to plan and execute routine behaviour when automaticity fails.