LATERALIZED FRONTAL BLOOD-FLOW INCREASES DURING FLUENCY TASKS - INFLUENCE OF COGNITIVE STRATEGY

Difficulties with verbal fluency tasks (VFIT) have been shown mainly t o be associated with left frontal lobe pathology in lesion studies. Th e design fluency test (DFT) is a non-verbal analogue of word fluency t asks and has, in patients with right frontal lobe pathology, been coup led to an inability to perform well. Regional cerebral blood flow meas urements (rCBF) were made in normals to elucidate the involvement of f rontal and frontotemporal brain regions during the performance of VFT and DFT. In addition, the subjects' reports were used for obtaining in formation about the cognitive strategy used when solving the tasks. Th e results confirm previous CBF findings showing a mainly left-sided fr ontal activation during the VFT. During the DFT significant flow augme ntations were seen in both frontal lobes compared to baseline. Further more, the use of different strategies was reflected in different patte rns of brain activation. Our results support the proposal that the lef t frontal cortical area is engaged in the generation of internally dri ven responses. Furthermore, we argue that the cortical areas engaged d uring the execution of these tasks may reflect differences in cognitiv e strategy. (C) 1998 Elsevier Science Ltd. All rights reserved.