A FRONTOPARIETAL NETWORK FOR RAPID VISUAL INFORMATION-PROCESSING - A PET STUDY OF SUSTAINED ATTENTION AND WORKING-MEMORY

The rapid visual information processing (RVIP) task, a lest of sustain ed attention which also requires working memory for its successful exe cution, has been used in a number of human psychopharmacological studi es. Single digits are presented in quick succession (100 or 200 digits /min) on a computer screen, and target sequences of numbers must be de tected with a button press. Although previous neuroimaging studies hav e implicated the frontal and parietal cortices in performance of simpl e sustained attention tasks, the neuroanatomical substrates of RVIP pe rformance are not yet known. This information would prove invaluable i n the interpretation of drug effects on this task, possibly delineatin g a neuron;al network for neurotransmitter action. Therefore, this stu dy investigated the functional anatomy of the RVIP task using positron emission tomography (PET) derived measures of regional cerebral blood flow (rCBF) in eight healthy volunteers. Subjects were required to pe rform variants of the RVIP task which manipulated both the level of wo rking memory load and the speed of stimulus presentation. Compared wit h a rest condition (eyes closed), the RVIP task increased rCBF bilater ally in the inferior frontal gyri, parietal cortex and fusiform gyrus, and also in the right frontal superior gyrus rostrally. In comparison with a simple sustained attention control condition, the aforemention ed right frontal activations were no longer apparent. We suggest that these data are consistent with the existence of a right fronto-parieta l network for sustained, and possibly selective: attention, and a left fronto-parietal network for the phonological loop component of workin g memory. Copyright (C) 1996 Elsevier Science Ltd.