It’s All in the Details: Relations Between Young Children’s Developing Pattern Separation Abilities and Hippocampal Subfield Volumes

Abstract

The ability to keep similar experiences separate in memory is critical for forming unique and lasting memories, as many events share overlapping features (e.g., birthday parties, holidays). Research on memory in young children suggests their memories often lack high-resolution details, i.e., show impoverished pattern separation (PS). Recently developed assessments of PS suitable for children allow us to relate the formation of distinct, detailed memories for the development of the hippocampus, a neural structure critical for this ability in adults. The hippocampus displays a protracted developmental profile and underlies the ability to form detailed memories. This study examined age-related differences in hippocampal subfield volumes in 4- to 8-year-old children and relations with performance on a mnemonic similarity task (MST) designed to index memory specificity. Results revealed age-moderated associations between MST performance and cornu ammonis 2-4/dentate gyrus subfields. Specifically, age-related differences in the ability to form detailed memories tracked with normative patterns of volume increases followed by reductions over this age range. That is, greater volume correlated with better performance in younger children, whereas smaller volume correlated with better performance in older children. These findings support the hypothesis that developmental differences in hippocampal circuitry contribute to age-related improvements in detailed memory formation during this period.

Empirical Evidence Supporting Neural Contributions to Episodic Memory Development in Early Childhood: Implications for Childhood Amnesia

“…Research has documented similar age‐related improvements in memory for details across early childhood using a variety of other paradigms, including memory for pairs of items or words (e.g., Yim, Dennis, & Sloutsky, ), the source of novel facts (e.g., Drummey & Newcombe, ; Riggins, ), and the spatial location in which an item was originally encountered (e.g., Bauer et al, ). Closely related research suggests that early childhood is a time when children’s ability to form very detailed memories and discriminate between them also improves (Canada, Ngo, Newcombe, Geng, & Riggins, ; Ngo, Newcombe, & Olson, ). Taken together, findings from laboratory‐based paradigms support the suggestion that an important transition in children’s ability to form and recall detailed memories occurs during early childhood.…”

“…Relations between dentate gyrus/cornu ammonis (CA) 2–4 subfields and (A) memory for details (as measured by the number of intra‐experimental errors on a source memory task) in the head of the hippocampus (Riggins et al, ) and (B) precision of memories (as measured by mnemonic discrimination) in the head and body of the hippocampus (Canada et al, ). In both studies, age moderated the association so that in younger children, larger volumes were associated with better performance, whereas in older children, smaller volumes were associated with better performance.…”

“…A third study probed the association between memory for details and the dentate gyrus more specifically. Researchers examined hippocampal subfields in relation to young children’s ability to discriminate between two similar events from memory (Canada et al, ). Developmental differences in relations between the precision of memories and the volume of the dentate gyrus/CA2–4 subfields appeared; in younger individuals, smaller volumes were associated with less precise memories, but in older children, smaller volumes correlated with more precise memories (see Figure B).…”

Gain‐Loss Framing Enhances Mnemonic Discrimination in Preschoolers

“…Recent findings indicate that mnemonic discrimination is quite poor during preschool ages, and improves markedly throughout early and middle childhood (Canada, Ngo, Newcombe, Geng, & Riggins, ; Ngo, Newcombe, & Olson, ; Rollins & Cloude, ), coinciding with the developmental window in which episodic memory shows the most robust gains (reviewed in Ghetti & Bunge, ; Olson & Newcombe, ). One paradigm designed to test mnemonic discrimination is the Mnemonic Similarity Task (MST), in which studied objects must be discriminated from perceptually similar objects at test (reviewed in Yassa & Stark, ).…”

Differential development of relational memory and pattern separation

“…Lure discrimination ability has consistently proven sensitive to changes in hippocampal function with aging and disease. More recently, variations on the MST have been employed in the study of hippocampal development and have shed light on the developmental trajectory of pattern separation, demonstrating changes in performance throughout early-to-middle childhood (Canada, Ngo, Newcombe, Geng, & Riggins, 2018;Keresztes et al, 2017;Ngo, Newcombe, & Olson, 2018;Rollins & Cloude, 2018), although variability in task design and performance calculation have presented challenges in interpreting findings across studies. Developmental neuroimaging work has also revealed age-moderated associations between MST performance and volume of select hippocampal subfields, including cornu ammonis 2-4/dentate gyrus (Canada et al, 2018), as well as overall structural maturity of the hippocampi (Keresztes et al, 2017).…”