Abstract
Stimuli in our environment compete for attention on a moment-to-moment basis. The ability to limit attention to task-irrelevant stimuli is an important aspect of behavior, but its neural mechanisms are poorly understood. Here, we used fMRI with a detection task in which targets were defined by a conjunction of color (e.g., orange) and location (e.g., on the left). The target’s color was constant over blocks of trials, but its location was cued on each trial. One distracter was always present in an uncued location. The two objects appeared in one of three conditions: neutral (i.e., neither were target-colored), target-colored distracter, or target-present. On target-colored distracter trials versus neutral trials, subjects were slower to respond that the target was absent. Results showed that the right temporoparietal junction (TPJ) was more active in the target-colored distracter condition than either the neutral or target-present condition. This result is consistent with previous findings that TPJ responds selectively to behaviorally relevant, but unattended stimuli as part of the stimulus-driven "ventral attention network"(Corbetta & Shulman, 2002). In contrast, regions of the "dorsal" attentional control network, including bilateral intraparietal sulcus (IPS) and frontal eye-fields (FEF), were activated by all conditions and correlated positively with RT. A correlational analysis of beta parameters taken from TPJ and IPS showed a negative correlation at the onset of the target location cue, but a positive correlation during the stimulus presentation. This suggests that TPJ is suppressed at the time of top-down attentional deployment in response to the spatial cue, but works with dorsal network regions (e.g., IPS) when an unattended stimulus may potentially contain critical information. Additional connectivity analyses conducted to further quantify the dynamics between TPJ and IPS demonstrated that the "dorsal" and "ventral" networks dynamically interact to control attention to reject distracters and select targets.
Meeting abstract presented at VSS 2012