Developmental Differences in Relations Between Episodic Memory and Hippocampal Subregion Volume During Early Childhood

Abstract

Episodic memory shows striking improvement during early childhood. However, neural contributions to these behavioral changes are not well understood. This study examined associations between episodic memory and volume of subregions (head, body, and tail) of the hippocampus-a structure known to support episodic memory in school-aged children and adults-during early childhood (n = 45). Results revealed significant positive relations between episodic memory and volume of the hippocampal head in both the left and right hemispheres for 6- but not 4-year-old children, suggesting brain-behavior relations vary across development. These findings add new information regarding neural mechanisms of change in memory development during early childhood and suggest that developmental differences in hippocampal subregions may contribute to age-related differences in episodic memory ability.

Figure 1

A) Head (pink), body (blue), and tail (green) for an individual participant. B) Slice illustrating where uncal apex is visible which marked the end of the head of the hippocampus, C) the next posterior slice where the uncal apex is no longer visible. D) Slice illustrating a portion of the body anterior to where the fornix separates from the hippocampus, E) the next posterior slice where the fornix is separated from the hippocampus.

Figure 2

Adjusted hippocampal volumes in left and right hemispheres for 4- and 6-year-old children. * indicates significantly larger volumes in right compared to left hemispheres, p<.05. † indicates marginally larger volumes in 6- compared to 4-year-old children, ps≤.08.

Figure 3

Associations between episodic memory and volume of the hippocampal head in left and right hemispheres for 4- and 6-year-old children. Only relations for 6-year-old children were significant. Correlation values were significantly greater in 6- versus 4-year-old children, ps<.05.