University of Maryland, College Park, MD, United States.
University of Maryland, College Park, MD, United States.
Neuroimage. 2018 Jul 1;174:127-137. doi: 10.1016/j.neuroimage.2018.03.009. Epub 2018 Mar 5.
The hippocampus is a structure that is critical for memory. Previous studies have shown that age-related differences in specialization along the longitudinal axis of this structure (i.e., subregions) and within its internal circuitry (i.e., subfields) relate to age-related improvements in memory in school-age children and adults. However, the influence of age on hippocampal development and its relations with memory ability earlier in life remains under-investigated. This study examined effects of age and sex on hippocampal subregion (i.e., head, body, tail) and subfield (i.e., subiculum, CA1, CA2-4/DG) volumes, and their relations with memory, using a large sample of 4- to 8-year-old children. Results examining hippocampal subregions suggest influences of both age and sex on the hippocampal head during early childhood. Results examining subfields within hippocampal head suggest these age effects may arise from CA1, whereas sex differences may arise from subiculum and CA2-4/DG. Memory ability was not associated with hippocampal subregion volume but was associated with subfield volume. Specifically, within the hippocampal head, relations between memory and CA1 were moderated by age; in younger children bigger was better, whereas in older children smaller was superior. Within the hippocampal body, smaller CA1 and larger CA2-4/DG contributed to better memory performance across all ages. Together, these results shed light on hippocampal development during early childhood and support claims that the prolonged developmental trajectory of the hippocampus contributes to memory development early in life.
海马体是对记忆至关重要的结构。先前的研究表明，该结构（即子区域）的长轴和内部电路（即子场）的年龄相关专业化差异与学龄儿童和成人的年龄相关记忆改善有关。然而，年龄对海马体发育的影响及其与生命早期记忆能力的关系仍未得到充分研究。本研究使用了一个包含 4 至 8 岁儿童的大样本，考察了年龄和性别的影响对海马体的子区域（即头、体、尾）和子场（即下托、CA1、CA2-4/DG）体积的影响，以及它们与记忆能力的关系。结果表明，在儿童早期，年龄和性别都会影响海马体头部。对海马体头部内的子场的研究结果表明，这些年龄效应可能源于 CA1，而性别差异可能源于下托和 CA2-4/DG。记忆能力与海马体子区域体积无关，但与子场体积有关。具体来说，在海马体头部，记忆与 CA1 之间的关系受年龄调节；在年龄较小的儿童中，体积越大越好，而在年龄较大的儿童中，体积越小越好。在海马体体部，较小的 CA1 和较大的 CA2-4/DG 有助于所有年龄段的更好的记忆表现。总的来说，这些结果揭示了儿童早期海马体的发育情况，并支持了这样的观点，即海马体的延长发育轨迹有助于生命早期的记忆发展。
