INHIBITION CAPACITY - A FRONTAL FUNCTION

It has been strongly suggested that one important function related to frontal lobes is inhibition. However, a review of the literature on cl assical tests of inhibition (Stroop test, WCST, and AB-AC learning) su ggests that this hypothesis is not well established We further examine d this hypothesis using short-term and long-term directed forgetting t asks (Reed, 1970; Zacks et al., 1996), the Stroop test and the Hayling test (Burgess & Shallice, 1996) in 13 patients with focal frontal les ions. The results revealed short-term and long-term memory deficits an d a slowing down, but no inhibition deficit compared with control subj ects. These results question the relevance of the hypothesis of the fr ontal lobe as the unique substrate of inhibitory mechanisms. More gene rally, they address the issue of executive functions : Are these susta ined by the frontal cortex or by a cortical and subcortical diffuse ne ural network?