PET REGIONAL CEREBRAL BLOOD-FLOW CHANGE DURING WORKING AND DECLARATIVE MEMORY - RELATIONSHIP WITH TASK-PERFORMANCE

Functional and anatomical relationships between working and declarativ e memory were investigated by contrasting regional cerebral blood flow (rCBF) change during standard working (Wisconsin Card Sorting Test, W CST) and declarative memory (Paired Associate Recognition Test, PART) tasks using identical stimulus-response modalities. The tasks and a re sting baseline were administered to 30 participants (16 men, 14 women) during successive 10-min positron emission tomography O-15-water meas ures of rCBF. For both tasks, rCBF increased over baseline in inferior frontal and occipitotemporal regions, with more consistent dorsolater al prefrontal activation for WCST than PART. Additional orbitofrontal increases and dorsomedial decreases were seen for the PART. Activation patterns diverged when performance was considered. For the WCST, high performers activated dorsolateral and inferior frontal regions, where as top PART performers activated only the occipitotemporal region. The se results suggest operation of a frontotemporal network subserving bo th types of memory function that becomes more focal as performance inc reases.