Abstract
It has been well known that the temporo-parietal junction (TPJ), a part of the ventral attention network, plays a crucial role in attentional reorienting. However, recently, some researchers showed that the TPJ was also associated with other cognitive processes, especially an evaluative process, which refers to inferring/computing the behavioral importance of the attended stimulus. Hence, we investigated whether a region involved in attentional reorienting is also engaged in evaluating the behavioral significance of attention-capturing stimuli. In an fMRI experiment, participants performed a modified Posner cueing task, in which four different arrow cues indicating four distinct locations were presented, followed by a target stimulus. Each cue predicted the target location to different extents; the cues predicted the target location with the probability of 80%, 20% (high-certainty cues), 60%, 40% (low-certainty cues). In each trial, participants made responses to a target, preceded by a cue stimulus. After four consecutive target responses, participants were required to infer how much each different cue predicts target location. We found that several fronto-parietal regions, frontal eye fields (FEF), medial superior parietal lobule (mSPL), and temporo-parietal junction of both hemispheres showed increased activity when the cued location mismatched with target location, evoking reorienting of attention. Notably, a dissociation across the orienting regions was found; the left and right TPJ activities were greater for high-certainty cues, whereas the FEF showed greater activity for low-certainty cues and mSPL showed similar activity for these cues. We suggest that the TPJ activation increased under the high-certainty cue presentation because this region is associated with utilizing sensory information to evaluate the behavioral significance of a stimulus; with the high-certainty cues, the amount of evidence for inferring the cue predictability should be abundant. By contrast, other fronto-parietal regions seem to be sensitive to increased task demand.