Schedule of Events | Symposia

Children’s but not adults’ CA2,3/DG differentiates same-category information in memory

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Sagana Vijayarajah¹ (sagana.vijayarajah@mail.utoronto.ca), Margaret Schlichting¹; ¹University of Toronto

Hippocampal subfields may demonstrate different representational schemes in the mature brain: Work in adults has shown that combined cornu ammonis 2,3 and dentate gyrus (CA2,3/DG) forms sparse, pattern separated representations in comparison to CA1 which instead forms relatively broader representations. Whether such codes exist throughout development remains unclear. The protracted development of CA2,3/DG versus CA1 connections might suggest that CA1's ability to form broad representations matures earlier than CA2,3/DG 's ability to form sparse ones. Children (N=42; 7-9 years) and adults (N=42) studied a series of photographs depicting 12 different scene categories and then performed a recognition test with new scenes that were either visually similar (matched lures) or dissimilar yet from the same category (same-category lures). We characterized how subfields represented memories by comparing neural patterns between studied scenes and similar scenes (matched lures and same-category lures); comparisons to unrelated scenes served as the baseline. In CA1, studied scenes were more similar to matched lures than same-category lures and baseline scenes across age groups, reflecting the subfield’s early emerging role in forming broad representations that emphasize perceptual overlap. CA2,3/DG representations instead varied by age group: While adults showed no differences in similarity to similar and baseline scenes, children actively separated studied scenes from same-category lures, making them less similar than other similar (matched lures) and baseline scenes. These results suggest how CA2,3/DG forms sparse representations changes over development, with children differentiating category-level overlap among experiences. The earlier maturation of broad subfield codes may scaffold the development of sparse representations.

Topic Area: LONG-TERM MEMORY: Episodic