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Kathryn Devaney, Emily Levin, Maya Rosen, Samantha Michalka, David Somers; fMRI-based Functional Localization of the Ventral Attention Network in Individual Subjects. Journal of Vision 2015;15(12):435. doi: https://doi.org/10.1167/15.12.435.
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Two well-known cortical networks support attention function – a dorsal attention network (DAN) for sustained, goal-directed attention and a ventral attention network (VAN) responsible for transient attentional shifts (Corbetta & Shulman, 2002). While the DAN is readily localizable in the brains of individual subjects by any of a number of attentionally demanding paradigms, the components of the VAN are more elusive, perhaps due to the transient nature of its function, and it is typically only described via large group averages. Group averaging methods for identifying regions of the VAN are potentially problematic due to the high intersubject anatomical variability and functional heterogeneity of those regions of the cortex. Here, we developed a rapid fMRI localizer (4 runs, 24 minutes) leveraging a modified Posner task and an oddball paradigm to identify the VAN in individual subjects. Participants (n=12) performed a 6-location variant of the Posner cueing task, with infrequent oddball images interspersed. Participants were required to discriminate between two highly similar targets, which could appear either at the cued location (valid 80%) or one of the other locations (invalid). Following the target phase, a standard mask appeared on 5/6th of the trials, however, on 1/6th of the trials, a rapid sequence of vivid trial-unique scene images (a.k.a. oddballs) appeared in a RSVP stream (5 images, 100ms per image) during the mask phase. Behaviorally, the expected reaction time cost of an invalid cue was observed (57ms). The fMRI contrast of oddball to non-oddball Posner trials successfully localized areas, in individual subjects, that have been identified as part of the VAN in many previous group-averaged analyses. This novel localizer will enable rapid progress towards pinpointing the explicit functional role of the VAN at the individual subject level.
Meeting abstract presented at VSS 2015
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