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Graduate Student Award Winner 

Age-Related Neural Dedifferentiation is Driven by Reduced Reliability

Poster Session F - Tuesday, March 10, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom
Also presenting in Data Blitz Session 2 - Saturday, March 7, 2026, 10:30 am – 12:00 pm PST, Salon D.

Tiantian Yang¹ (), Molly Simmonite¹, Bingjie Liu¹, Ethan Maddox¹, Noah Reardon¹, Kayla Wyatt¹, Thad Polk¹; ¹University of Michigan

The distinctiveness of neural activation patterns in response to different stimulus categories (e.g., faces vs. houses) is typically reduced in older vs. younger adults. Such so-called age-related neural dedifferentiation has been observed across multiple brain regions and been associated with cognitive declines. Neural distinctiveness is often measured as the difference between within-category similarity (reliability) and between-category similarity (confusability) of neural activation patterns. Our previous cross-sectional work suggested that age differences in both within- and between-category similarity contribute to dedifferentiation (Simmonite & Polk, 2022), but cohort effects could not be ruled out because the analysis was cross-sectional. Here, we extended this analysis using longitudinal data. Sixty young adults (18-29 years) and 156 older adults (65-87 years) completed auditory (speech vs. music), visual (faces vs. houses), and motor (left vs. right hand) fMRI tasks. We estimated cross-sectional age differences in within-category similarity, between-category similarity, and neural distinctiveness within individualized ROIs in task-relevant cortical areas. Fifty-one older adults returned 3-5 years later to complete the same tasks, enabling longitudinal analysis. Cross-sectionally, older adults showed significantly reduced within-category similarity compared with the young adults across all three ROIs and reduced neural distinctiveness in the motor and visual ROIs. Between-category similarity showed no significant age differences in any ROI. Longitudinally, only within-category similarity declined significantly with age, most prominently in visual cortex, with no significant effects on distinctiveness or between-category similarity. These findings suggest age-related neural dedifferentiation is primarily driven by reduced reliability of neural activation patterns rather than increased confusability between categories.

Topic Area: PERCEPTION & ACTION: Development & aging