Supervisory attentional system in patients with focal frontal lesions

The aim of this study was to re-examine the hypothesis of a link between frontal cortex and the Supervisory Attentional System (SAS; Shallice, 1988). Contrary to previous studies that examined patients with lesions extending beyond the frontal lobes (Shallice, 1982; Burgess & Shallice, 1996a, 1996b), SAS or executive functions were evaluated in a group of patients with strict frontal lesions. Three tasks (Tower of London -TOL-, Hayling and Brixton tests) designed to assess specific SAS processes (planning, inhibition and abstraction of logical rules respectively) were administered. In the TOL test, although frontal patients were slower than control participants, the two groups did not differ in their ability to solve problems. Furthermore, the two groups did not differ in terms of performance in the Hayling and Brixton tests either. These results are discussed in terms of the SAS model and are compared to those observed by Shallice (1982) and Burgess & Shallice (1996a, 1996b). Additionally, the issue of the neural subtract of executive functions is addressed.