Functional specialization of hippocampal subfields in young children
Qijing Yu1, Sruthi Ramesh1, Bryn Thompson1, David Chen1, Mayu Nishimura1,2, Noa Ofen1; 1Wayne State University, 2McMaster University
Episodic memory undergoes robust development during childhood and is dependent on the function of the hippocampus, a complex structure composed of cytoarchitectonically distinct subfields (Cornu Ammonis, CA; dentate gyrus, DG, Subiculum). Hippocampal subfields are thought to support complementary memory processes with the CA3 and DG supporting the ability to retrieve information based on partial cues and to distinguish between similar experiences. Recent advances in neuroimaging allows better visualization and reliable quantification of individual differences in hippocampal subfield volume in children, paving the way to testing hypotheses about the functional specialization of the hippocampal subfields and the role such functional specialization plays in accounting for memory functioning in children. We examined the relation between hippocampal subfield volumes, measured based on manual demarcation with high reliability (ICC(2)≥0.85), and episodic memory functioning, measured using stimuli of varied degree of similarity, in 5-6 year-old children (N=36, 42% females, M=6.19). Participants studied stimuli consisting of several exemplars from a category (‘within’ category) intermixed with single exemplars from other categories (‘across’ category), and were later given a yes/no recognition test. Memory sensitivity (d’) for ‘across’, but not ‘within’, category was related to the volumes of CA1-2 (F(1,31)=8.02, p=0.008) and Subiculum (F(1,31)=5.75, p=0.02). In contrast, memory sensitivity for both ‘within’ and ‘across’ category stimuli was related to the volume of CA3-DG (F(1,31)=7.59, p=0.01). These findings are consistent with the idea that CA3-DG uniquely supports memory that requires the representation of fine details and demonstrate such functional specialization of the hippocampal subfields in young children.
Topic Area: LONG-TERM MEMORY: Development & aging