TY - JOUR T1 - Foreground Enhancement and Background Suppression in Human Early Visual System During Passive Perception of Natural Images JF - bioRxiv DO - 10.1101/109496 SP - 109496 AU - Paolo Papale AU - Andrea Leo AU - Luca Cecchetti AU - Giacomo Handjaras AU - Kendrick Kay AU - Pietro Pietrini AU - Emiliano Ricciardi Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/02/23/109496.abstract N2 - One of the major challenges in visual neuroscience is represented by foreground-background segmentation, a process that is supposed to rely on computations in cortical modules, as information progresses from V1 to V4. Data from nonhuman primates (Poort et al., 2016) showed that segmentation leads to two distinct, but associated processes: the enhancement of cortical activity associated to figure processing (i.e., foreground enhancement) and the suppression of ground-related cortical activity (i.e., background suppression). To characterize foreground-background segmentation of natural stimuli in humans, we parametrically modulated low-level properties of 334 images and their behaviorally segmented counterparts. A model based on simple visual features was then adopted to describe the filtered and intact images, and to evaluate their resemblance with fMRI activity in different visual cortices (V1, V2, V3, V3A, V3B, V4, LOC). Results from representational similarity analysis (Kriegeskorte et al., 2008) showed that the correspondence between behaviorally segmented natural images and brain activity increases throughout the visual processing stream. We found evidence of foreground enhancement for all the tested visual regions, while background suppression occurs in V3B, V4 and LOC. Our results suggest that foreground-background segmentation is an automatic process that occurs during natural viewing, and cannot be merely ascribed to differences in objects size or location. Finally, “neural images” reconstructed from V4 and LOC fMRI activity revealed a preserved spatial resolution of foreground textures, indicating a richer representation of the salient part of natural images, rather than a simplistic model of objects shape.Significance Statement In the path from continuous sensory percepts to discrete categorical representations, foreground-background segmentation has been considered a pivotal step, in order to make sense of the surrounding visual environment. Our findings provide novel support to the hypothesis that foreground-background segmentation of natural scenes during passive perception is an automatic process sustained by the distributed activity of multiple areas across the visual processing stream. Specifically, V3B, V4 and LOC show a background suppression effect, while retaining texture information from the foreground. These observations challenge the idea that these regions of the visual system may primarily encode simple object representations based on silhouette or shape features only. ER -