Language and cognitive deficits resulting from medial and dorsolateral frontal lobe lesions.

A total of 36 patients with chronic unilateral circumscribed medial and dorsolateral frontal lobe lesions were investigated with a range of neuropsychological tests. Lateralized deficits in tasks depending on language functions were found with dorsolateral but not with medial lesions. The specific role of Broca's area could not be confirmed. Lesions of the supplementary motor area led to mild deficits in tests of "concept formation". Frontomedial lesions situated more deeply in the interhemispheric fissure resulted in memory deficits. The results are discussed on the basis of recent neurophysiological theories of brain function.