Novelty Discrimination of Configural Objects in the Perirhinal and Anterolateral Entorhinal Cortices Is Impacted by...

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 object with overlapping features. In older adults, gray matter volume of the anterolateral entorhinal cortex (alERC), a PRC-adjacent region, correlated with object discrimination based on configural (spatial) arrangements of features. However, this relationship has not yet been examined with functional activation or systematically investigated in aging. Importantly, object novelty discrimination 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 functional roles of the PRC/alERC is complicated by interindividual 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 43 younger (32 females) and 47 older adults (33 females) performing a configural object processing task with concurrent eye-tracking. In younger adults, gaze behavior and PRC activity distinguished both feature and configural novelty, whereas alERC activity was sensitive to configural novelty. 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 the critical role of the alERC in object processing and reveal age-related changes in the PRC/alERC during novelty discrimination of complex objects.