Organization of pRF size along the AP axis of the hippocampus is related to specialization for scenes

The hippocampus is largely recognized for its integral contributions to memory processing. By contrast, its role in perceptual processing remains less clear. Hippocampal properties differ along the anterior-posterior (AP) axis. Based on past research suggesting a gradient in the scale of features processed along the anterior-posterior extent of the hippocampus, the representations have been proposed to differ as a function of granularity along this axis. One way to quantify such granularity is with population receptive field (pRF) size measured during visual processing, which has so far received little attention. In this study, we compare the pRF sizes within the hippocampus to its activation for images of scenes versus faces. We also measure these functional properties in surrounding medial temporal lobe (MTL) structures. Consistent with past research, we find pRFs to be larger in anterior than in the posterior hippocampus. Critically, our analysis of surrounding MTL regions, such as the perirhinal cortex, entorhinal cortex and parahippocampal cortex, shows a similar relationship between scene sensitivity and larger pRF size. These findings provide conclusive evidence for a tight relationship between pRF size and the sensitivity to image content in the hippocampus.