Distinct modulation of FEF during orienting and reorienting of exogenous and endogenous attention

Attention is a fundamental cognitive function that enhances the selective processing of important stimuli. Orienting of attention can be bottom-up and stimulus-driven (exogenous attention), or top-down and goal-directed (endogenous attention). It is well established that cortical areas along the visual hierarchy are differentially modulated by exogenous and endogenous attention. During exogenous attention, modulation of stimulus-evoked activity is constant along the visual hierarchy. But for endogenous attention, the enhancement of stimulus processing increases along the visual hierarchy. The source of this enhanced activity in the visual cortex remains unknown. Here we tested the hypothesis that the human frontal eye field (FEF) differentially modulates exogenous and endogenous attention. We measured cortical activity in human observers while they performed an orientation discrimination task (Dugue et al., 2020) that required either voluntary (endogenous) or involuntary (exogenous) allocation of attention prior to the onset of a target stimulus (7T BOLD fMRI, 1.8 x 1.8 x 1.8 mm). Performance accuracy was higher when the location of the target matched the cued location (valid trials), than when the cued and target locations did not match (invalid trials). While both forms of attentional orienting induced similar behavioral cue-validity effects, they evoked different BOLD fMRI responses in FEF. In the exogenous attention task, invalid cues evoked larger BOLD response than valid cues, suggesting that FEF is involved in reorienting attention from the invalidly cued location to the target location. In contrast, in the endogenous attention task, both valid and invalid trials evoked similar BOLD responses, consistent with a role for FEF in internally directing the focus of attention. Our results demonstrate that FEF exhibits distinct patterns of BOLD activity during attentional orienting and reorienting. Ongoing studies will evaluate whether attentional modulation in FEF predicts the pattern of activity observed in visual cortex during attentional reorienting.