The hippocampus is critical for spatial relational attention

The hippocampus is traditionally considered to be a system that is specialized for long-term memory. Recent work has challenged this notion by demonstrating that this region can contribute to many domains of cognition beyond long-term memory, including perception and attention. One potential reason why the hippocampus contributes broadly to cognition is that it contains relational representations - representations of muli-dimensional features of experience - that are useful in many different cognitive domains. Here, we explore the hypothesis that the hippocampus plays a critical role in attention via its relational representations. We compared human participants with hippocampal damage to healthy age- and education-matched individuals on attention tasks that varied in the type and amount of relational processing required. On each trial, participants viewed two images (rooms with paintings). On room relational trials, they judged whether the rooms had the same spatial layout from a different perspective. On art relational trials, they judged whether the paintings could have been painted by the same artist. Control trials placed fewer demands on relational processing: Participants simply had to detect identical paintings or rooms. Patients with hippocampal damage were significantly impaired on the room relational task. Selective hippocampal lesions had comparable effects to more extensive medial temporal lobe damage, suggesting that the hippocampus itself plays a critical role in spatial relational attention. This work provides further evidence that the hippocampus plays a ubiquitous role in cognition by virtue of its relational representations, and highlights that spatial relations may be particularly important.