Age-related neural dedifferentiation: Unveiling the role of functional connectivity and network reorganization
Claire Pauley1,2 (firstname.lastname@example.org), Dagmar Zeithamova3, Myriam C. Sander1; 1Max Planck Institute for Human Development, 2Humboldt University of Berlin, 3University of Oregon
‘Age-related neural dedifferentiation’, the finding that neural representations of information are less distinctive in older adults compared with younger adults, has been reported to underly age differences in memory performance. However, little is known about how brain-wide neural changes in old age contribute to age-related neural dedifferentiation. Here, we explored whether age-related differences in functional network organization explain neural dedifferentiation in category-selective visual regions. In this study, 35 younger and 34 older adults viewed blocks of faces and houses in the fMRI scanner. Using multivoxel pattern analysis, we identified age differences in the distinctiveness (operationalized as the difference between within-category and between-category similarity) of face processing in the fusiform gyrus (FG) and house processing in the parahippocampal gyrus (PHG). Using background connectivity, we found that younger adults had greater connectivity between the FG and the visual network than older adults. Crucially, interindividual differences in connectivity were related to neural distinctiveness, suggesting that age-related disruptions in communication between category-selective regions and the visual network may explain dedifferentiated category representations. Furthermore, we observed age differences in global network structure, defined as the functional segregation of the visual network from the default mode network. Older adults exhibited less coherent network structures than younger adults, a phenomenon referred to as network-level dedifferentiation. Finally, we found a relationship between dedifferentiated category representations and dedifferentiated network structure. Thus, we provide evidence supporting the idea that senescent reorganization of functional networks and differences in connectivity to category-selective regions may be an underlying cause of age-related neural dedifferentiation.
Topic Area: LONG-TERM MEMORY: Development & aging
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April 13–16 | 2024