Abstract
We recently demonstrated that attention to visual categories is associated with increased coupling between low-level visual areas selective for basic features and high-level areas selective for the attended category (Al-Aidroos, Said, & Turk-Browne, 2012, PNAS). For example, retinotopic area V4 coupled more with the fusiform face area (FFA) under face attention and the parahippocampal place area (PPA) under scene attention. Here, we investigate how spatial attention affects coupling, and how such modulation might interact with category-based coupling. Conventional neural measures often suggest that spatial and feature-based/category-based attention operate independently, so integrated changes in coupling may help to explain how people coordinate multiple attentional goals. Participants completed a combined space/category attention task in which they fixated centrally while viewing face images on one side of fixation and scene images on the other. Thus, across fMRI runs, they attended to left faces, right faces, left scenes, or right scenes. All images appeared in the upper visual field, projecting to the perceptually-dominant ventral stream. We used background connectivity to assess coupling: Stimulus-evoked responses and global noise were removed from the data, allowing analysis of the noise correlations between areas for the four attentional states. We found three main results. First, when attending to upper visual field images, FFA/PPA connectivity was enhanced for ventral V1-V3, but suppressed for dorsal V1-V3. Second, attending to images in one hemifield enhanced FFA/PPA connectivity with contralateral, more than ipsilateral, visual areas. These spatial attention results generalize our previous category findings, suggesting that modulation of coupling is a fundamental mechanism for top-down attention. Third, enhanced connectivity with task-relevant category areas was limited to task-relevant spatial areas (e.g., left-face attention enhanced FFA but not PPA connectivity, and only with right but not left V4). In this way, changes in coupling can support the integration of two distinct types of top-down attention.
Meeting abstract presented at VSS 2013