Repeated contextual search cues lead to reduced BOLD-onset times in early visual and left inferior frontal cortex

Abstract

Repetition of context can facilitate search for targets in distractor-filled displays. This contextual cueing goes along with enhanced event-related brain potentials in visual cortex, as previously demonstrated with depth electrodes in the human brain. However, modulation of the BOLD-response in striate and peristriate cortices has, to our knowledge, not yet been reported as a consequence of contextual cueing. In an event-related fMRI experiment with 16 participants, we observed a selective reduction of the BOLD onset latency for repeated distractor configurations in these areas. In addition, the same onset latency reduction was observed in posterior inferior frontal cortex, a potential source area for feedback signals to early visual areas. These latency changes occured in the absence of differential BOLD time-to-peak and BOLD-amplitude for repeated versus new displays. The posterior part of left inferior frontal cortex has previously been linked to repetition priming, however in the form of repetition suppression. These studies differ from ours in many respects, such as awareness of stimulus repetition and semantic processing. The overlap of activation found in previous priming studies and in the current experiment does not allow the reverse inference that the same mechanisms are involved in contextual cueing and priming. However, future experiments may investigate the mechanisms that lead to repetition suppression versus BOLD-onset reduction in left posterior inferior frontal cortex and visual cortex, thereby elucidating the commonalities or differences between repetition priming and contextual cueing.