Abstract
Configural face processing, the processing of the spatial relationships among the features of a face, is considered vital for face perception. If configural face processing depends on spatial information, might this process involve interactions between the face-processing regions of the ventral stream and visuospatial processing regions of the dorsal stream? Here, we used thetaburst TMS (TBS) with fMRI to examine how interference of localized spatial-processing regions of the dorsal stream affects the BOLD activity and pattern of functional connectivity of face-processing regions in the ventral stream during a same-different face detection task. Participants were presented with two face exemplars, appearing simultaneously on a screen that could differ in terms of the shape (featural differences) or the spatial configuration of their features (configural differences; Zachariou et al. 2016). Featural and configural differences were matched in difficulty as measured by RT and accuracy separately for each participant. Dorsal spatial-processing regions acted as the active TBS sites and the vertex acted as the control site. When TBS was applied on the location-processing regions of the dorsal stream, the magnitude of the BOLD activity within the right occipital face area (OFA) and right anterior inferior temporal (aIT) regions decreased in response to configural but not featural face processing. The above effect was not observed for the vertex control site. Crucially, TBS on the dorsal location-processing regions decreased the level of functional connectivity between bilateral OFA, aIT, right fusiform face area (FFA), and the dorsal location-processing regions (the TBS targets), significantly more for configural than featural face processing. No changes in the pattern of functional connectivity were observed when TBS was delivered on the vertex control site for either face task. We conclude that the location-processing substrates of the dorsal stream exchange visusospatial information with face-processing regions of the ventral stream during configural face processing.
Meeting abstract presented at VSS 2017