Resting-state functional connectivity of the human hippocampus in periadolescent children: Associations with age and memory performance.

The hippocampus is necessary for declarative (relational) memory, and the ability to form hippocampal-dependent memories develops through late adolescence. This developmental trajectory of hippocampal-dependent memory could reflect maturation of intrinsic functional brain networks, but resting-state functional connectivity (rs-FC) of the human hippocampus is not well-characterized for periadolescent children. Measuring hippocampal rs-FC in periadolescence would thus fill a gap, and testing covariance of hippocampal rs-FC with age and memory could inform theories of cognitive development. Here, we studied hippocampal rs-FC in a cross-sectional sample of healthy children (N = 96; 59 F; age 9-15 years) using a seed-based approach, and linked these data with NIH Toolbox measures, the Picture-Sequence Memory Test (PSMT) and the List Sorting Working Memory Test (LSWMT). The PSMT was expected to rely more on hippocampal-dependent memory than the LSWMT. We observed hippocampal rs-FC with an extensive brain network including temporal, parietal, and frontal regions. This pattern was consistent with prior work measuring hippocampal rs-FC in younger and older samples. We also observed novel, regionally specific variation in hippocampal rs-FC with age and hippocampal-dependent memory but not working memory. Evidence consistent with these findings was observed in a second, validation dataset of similar-age healthy children drawn from the Philadelphia Neurodevelopment Cohort. Further, a cross-dataset analysis suggested generalizable properties of hippocampal rs-FC and covariance with age and memory. Our findings connect prior work by describing hippocampal rs-FC and covariance with age and memory in typically developing periadolescent children, and our observations suggest a developmental trajectory for brain networks that support hippocampal-dependent memory.