Novelty discrimination of configural objects in the perirhinal and anterolateral entorhinal cortices is impacted by aging

The representational-hierarchical account of object processing characterizes the perirhinal cortex (PRC) as supporting conjunctive representations of object features, such that damage or age-related decline in the PRC impairs discrimination between complex objects with overlapping features. In older adults, grey matter volume of the anterolateral entorhinal cortex (alERC), a PRC-adjacent region, correlated with object discrimination based on the configural (i.e., spatial) arrangement of features. However, this relationship has not yet been examined with functional activation or systematically investigated in aging. Importantly, discrimination of object novelty can rely on changes at the feature-level (where all features are novel) or configural-level (where familiar features are rearranged in novel configurations), and the PRC/alERC may differentially support these processes – differences that may become more pronounced with age-related neurodegeneration. However, distinguishing the functional roles of the PRC/alERC is complicated by inter-individual variability in their anatomical boundaries that may be exacerbated by aging. In the present fMRI study, we manually delineated the PRC/alERC in a group of younger and older adults performing a configural object processing task with concurrent eye-tracking. In younger adults, gaze behavior and PRC activity distinguished novelty at both feature and configural levels, whereas alERC tracked configural novelty selectively. In contrast, age-related decline was most evident in the PRC’s activation to configural novelty, and older adults showed no novelty-related differentiation in gaze behavior or alERC function. These findings suggest a critical role for the alERC in object processing and reveal age-related changes in the PRC/alERC during novelty discrimination of complex objects.