Functional Organization of the Perirhinal Cortex in Natural Scene Processing and Memory

The perirhinal cortex (PRC) has long been implicated in object perception and recognition memory; however, its role in processing complex natural scenes and its internal functional organization are not well understood. In the current study, we investigated the relationship between object- and scene-related visual feature (faces, bodies, and place) representations in PRC and the visual cortex, and the spatial pattern within PRC for visual processing and memory. Utilizing fMRI data from a continuous recognition task involving natural scenes (from the Natural Scenes Dataset), we first quantified the trial-by-trial decoding accuracy for visual features across distributed visual cortical regions and within the PRC. Our results demonstrate that multivariate pattern feature decodability in the PRC increase significantly when visual features are broadly represented across distributed regions in visual cortex. The PRC exhibited a robust subsequent memory effect, though the memory outcome was not directly predicted by the level of distributed visual feature representation. Critically, left PRC showed a posterior bias for the multivariate decoding of the place feature. Vertex-level univariate analyses uncovered a posterior bias for face-feature-driven vertices and an anterior bias for memory-driven vertices, which is more consistent in the right PRC. Together, these findings suggest that the PRC may play a flexible role in scene processing that extends beyond object representation and highlights an anterior-posterior functional gradient within the human PRC that supports perceptual or mnemonic processes.