Anterior cingulate and dorsolateral prefrontal cortex involvement in preparatory attention

NemoImage

13, Number

6, 2001, Part 2 of 2 Parts 10

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ATTENTION

Anterior Cingulate and Dorsolateral Prefrontal Cortex Involvement in Preparatory Attention T.L. Luks, R.J. FeiwelI, W.L. Miller, G.V. Simpson Department

of Radiology,

University

of California,

San Francisco

Introduction: Two frontal brain regions, Anterior Cingulate Cortex (ACC) involved in attentional control and self-monitoring. There is DLPFC is specifically responsible for allocating attention to stimulus processing and response selection. The aim of this allocation of attention prior to stimulus processing. In this performed a cued attentional-switch task, in which preparatory changed.

and Dorsolateral Prefrontal Cortex (DLPFC) appear to be particularly evidence that while these regions work in tandem to regulate behavior, meet task demands, and ACC is specifically responsible for monitoring study was to investigate the roles of DLPFC and ACC in preparatory study, we measured event-related BOLD fMRl activity while subjects reallocation of attention was selectively required when task demands

Methods: Event-related BOLD fMRI activity was measured in 7 healthy volunteers on a 1.5T GE scanner using EPI images (TR=3sec, 19 slices, 5mm thick, 1 mm gap). Each trial consisted of a 5OOmsec cue, a 2.5-5sec inter-stimulus interval, a 500msec target digit, and a 5.5-7.5sec inter-trial interval. If the digit was red, subjects decided if it was odd or even. If the digit was blue, they decided if it was greater or less than five. The cue was either informative of task demands or neutral. Task demands switched every 1-4 trials. For trials with informative cues, the task demands were signaled by the cue (i.e. switch or no-switch), whereas for the trials with neutral cues, subjects were not aware of the task demands until the target digit was presented. BOLD fMR1 activity was assessed separately for cue and target stimuli. Subjects completed 5 runs of 30 trials. Images were motion-corrected, normalized to Talairach space, smoothed and statistically analyzed using SPM99. Results: Right ACC activity was significantly greater following informative switch cues than informative no-switch cues (t=7.92. p<.OOl uncorrected for mulitple comparisons) and than neutral cues (t=5.57, p<.OOl), but did not differ for informative no-switch versus neutral cues. Right DLPFC activity was significantly greater following informative cues (both switch and no-switch) than neutral cues (t=8.46, p<.OOl), but did not differ significantly for informative switch versus no-switch cues. Neither ACC or DLPFC were significantly active following target presentation, or selectively more active following switch targets than no-switch targets. Discussion: These results suggest that DLPFC was generally involved in the preparatory allocation of attention, but not differentially involved in the preparatory switching of attention between task demands. In contrast, ACC was selectively involved in the preparatory switching of attention prior to stimulus processing.

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