AN (18)FDG-PET STUDY OF CORTICAL ACTIVATION DURING A SHORT-TERM VISUAL MEMORY TASK IN HUMANS

Studies of subhuman primates and man have shown that the prefrontal co rtex is important for spatial working memory; We have used (18)fluorod eoxyglucose positron emission tomography ((18)FDG-PET) to study a non- spatial, abstract visual memory task of in man. Using a regions-of-int erest approach with discrimant analysis of the relative regional cereb ral metabolic rate of glucose consumption (rCMRGlc), we found that cha nges in dorsal prefrontal, premotor/motor frontal and posterior cingul ate areas differentiated the primary memory task from the control task . Less robust increases in glucose uptake were observed in lateral par ietal cortex, while some subcortical and limbic regions showed decreas es. This is the first activation study with a non-spatial, visual task . These results complement previous studies in that they substantiate the role of the prefrontal cortex in the mediation of cross-temporal c ontingencies of behavior, and point to a role of the premotor region i n this mediation as well.