Activity in perirhinal and entorhinal cortex predicts observer-specific perceived visual similarities between objects

Abstract

Observers perceive their visual environment in unique ways. How ventral visual stream (VVS) regions represent subjectively perceived object characteristics remains poorly understood. We hypothesized that the visual similarity between objects that observers perceive is reflected with highest fidelity in neural activity patterns in perirhinal and anterolateral entorhinal cortex at the apex of the VVS object-processing hierarchy. To address this issue with fMRI, we administered a task that required discrimination between images of exemplars from real-world categories. Further, we obtained ratings of perceived visual similarities. We found that perceived visual similarities predicted discrimination performance in an observer-specific manner. As anticipated, activity patterns in perirhinal and anterolateral entorhinal cortex predicted perceived similarity structure, including those aspects that are observer-specific, with higher fidelity than any other region examined. Our findings provide new evidence that representations of the visual world at the apex of the VVS differ across observers in ways that influence behaviour.