Hippocampal functional connectivity and episodic memory in early childhood

Abstract

Episodic memory relies on a distributed network of brain regions, with the hippocampus playing a critical and irreplaceable role. Few studies have examined how changes in this network contribute to episodic memory development early in life. The present addressed this gap by examining relations between hippocampal functional connectivity and episodic memory in 4-and 6-year-old children (n=40). Results revealed similar hippocampal functional connectivity between age groups, which included lateral temporal regions, precuneus, and multiple parietal and prefrontal regions, and functional specialization along the longitudinal axis. Despite these similarities, developmental differences were also observed. Specifically, 3 (of 4) regions within the hippocampal memory network were positively associated with episodic memory in 6-year-old children, but negatively associated with episodic memory in 4-year-old children. In contrast, all 3 regions outside the hippocampal memory network were negatively associated with episodic memory in older children, but positively associated with episodic memory in younger children. These interactions are interpreted within an interactive specialization framework and suggest the hippocampus becomes functionally integrated with cortical regions that are part of the hippocampal memory network in adults and functionally segregated from regions unrelated to memory in adults, both of which are associated with age-related improvements in episodic memory ability.

Development of hippocampal functional connectivity during childhood

“…In adults, this method does not elicit significant differences in hippocampal connectivity in comparison to a standard fixation resting-state scan, providing preliminary evidence that a non-canonical resting-state scan may be used to tap the hippocampal network without eliciting significantly altered connectivity [see Supporting Information; Greicius et al, 2003;Riggins et al, 2016;Vanderwal et al, 2015]. 2 There were no significant differences in results when left-handed participants were excluded.…”

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

“…Specifically, functional connectivity between the hippocampus and cortical regions was influenced by age and performance. These studies also suggested that functional connectivity between the hippocampus and regions not typically thought to relate to memory formation in adults decreased developmentally (i.e., the orbital frontal gyrus and left and right middle temporal gyrus in Geng et al, ; the right inferior frontal gyrus in Riggins et al, ).…”

“…Two studies have explored relations between task‐free hippocampal functional connectivity and memory ability assessed outside the MRI scanner in young children (Geng et al, ; Riggins, Geng, Blankenship, & Redcay, ). Findings from both studies were similar to those from task‐based fMRI studies.…”

The role of experience in adolescent cognitive development: Integration of executive, memory, and mesolimbic systems

“…In adolescents and adults, but not children, the volume of the anterior hippocampus as well as functional activation of the anterior hippocampus and prefrontal cortex predict better associative memory performance (DeMaster et al, 2014). Critically, research investigating pre-adolescent development have detailed increases in associative memory processes as well as changes in connectivity between the hippocampus and prefrontal cortex (Riggins, Geng, Blankenship, & Redcay, 2016). However, the extant evidence above shows that these processes approach adult levels in adolescence.…”