Stroop performance in focal lesion patients: dissociation of processes andfrontal lobe lesion location

There were three primary objectives: to examine the usefulness of the Stroo p interference effect as a measure of frontal lobe function; to investigate the possibility of distinct lesion effects for word reading or color namin g; and to specifically determine the brain regions necessary for the perfor mance of the incongruent condition. Fifty-one patients with single focal br ain lesions in frontal and non-frontal regions and 26 normal control subjec ts (CTL) were administered the word reading, color naming and incongruent c onditions of the Stroop task. Only frontal lesions produced significant imp airment. Patients with posterior lesions were not significantly deficient i n any condition. Damage to the left dorsolateral frontal lobe resulted in i ncreased errors and slowness in response speed for color naming. Contrary t o Ferret (Neuropsychology, 1974; 12: 323-330), lesions of the left frontal lobe did not result in a selective interference deficit on the Stroop incon gruent condition. Father, bilateral superior medial frontal damage was asso ciated with increased errors and slowness in response time for the incongru ent condition, This result is interpreted as failure of maintenance of cons istent activation of the intended response in the incongruent Stroop condit ion. The results and conclusion are compatible with the prevalent theories of both the Stroop effect and the role of the superior medial frontal regio ns. The role of the anterior cingulate cortex on performance of the Stroop task is likely related to task and patient context. (C) 2001 Elsevier Scien ce Ltd. All rights reserved.