Visual areas PPA and pSTS diverge from other processing modules during perceptual closure: functional dichotomies within category selective networks.

Abstract The nature of neural processing within category-preferring visual networks remains an open topic in human neuroscience. Although the topography of face, scene, and object-preferring modules in the human brain is well established, the functional characterization, in terms of dynamic selectivity across their nodes is still elusive. Here, we use long trials of perceptually impoverished images of faces and objects to assess the dynamics of BOLD activity and selectivity induced by perceptual closure within these regions of interest. Departing from paradigms involving immediate percepts, we used ambiguous images favoring holistic search and independence from low level stimulus properties. By assessing the neural responses to images that go beyond the preferred category of the studied ROIs we could dissect the specificity of these processes as a function of the timing of perceptual closure and contribute to the debate regarding specialization of these modules. We found that pSTS is a notable exception to the observation that category selective high-level visual areas also participate on the perceptual closure of their non-preferred category. A similar observation was found for PPA responses to faces. Most importantly, these observations directly link the pSTS region with the social processing network, which cannot be engaged by object stimuli.