Are central executive functions working in patients with focal frontal lesions?

The aim of this study was to examine the hypothesis of a link between frontal cortex and two executive functions in working memory: the capacity to perform a dual task and the ability to inhibit irrelevant information. A dual task designed to assess the capacity to perform storage and processing simultaneously and a directed forgetting task designed to assess the capacity to actively inhibit no-longer relevant information were administered to a group of patients with focal frontal lesions and to a group of control participants. The results revealed that despite showing reduced short-term storage, frontal patients performed the dual task and inhibited the no-longer relevant information as well as control participants. These findings suggest that not all-executive processes are exclusively sustained by the frontal cortex [Quart J Exp Psychol 9 (1996) 5; Curr Opin Neurobiol 10 (2000) 195; Neuropsychology (1994) 544; The Cognitive Neuropsychology of Alzheimer-type dementia. Oxford, New York: Oxford University Press, 1996].