Laboratory of Brain and Cognitive Development, Institute of Psychology, University of Lausanne, Lausanne, Switzerland.
Department of Medicine, University of Fribourg, Fribourg, Switzerland.
J Comp Neurol. 2020 Oct;528(14):2308-2332. doi: 10.1002/cne.24897. Epub 2020 Mar 18.
The entorhinal cortex is the main gateway for interactions between the neocortex and the hippocampus. Distinct regions, layers, and cells of the hippocampal formation exhibit different profiles of structural and molecular maturation during postnatal development. Here, we provide estimates of neuron number, neuronal soma size, and volume of the different layers and subdivisions of the monkey entorhinal cortex (Eo, Er, Elr, Ei, Elc, Ec, Ecl) during postnatal development. We found different developmental changes in neuronal soma size and volume of distinct layers in different subdivisions, but no changes in neuron number. Layers I and II developed early in most subdivisions. Layer III exhibited early maturation in Ec and Ecl, a two-step/early maturation in Ei and a late maturation in Er. Layers V and VI exhibited an early maturation in Ec and Ecl, a two-step and early maturation in Ei, and a late maturation in Er. Neuronal soma size increased transiently at 6 months of age and decreased thereafter to reach adult size, except in Layer II of Ei, and Layers II and III of Ec and Ecl. These findings support the theory that different hippocampal circuits exhibit distinct developmental profiles, which may subserve the emergence of different hippocampus-dependent memory processes. We discuss how the early maturation of the caudal entorhinal cortex may contribute to path integration and basic allocentric spatial processing, whereas the late maturation of the rostral entorhinal cortex may contribute to the increased precision of allocentric spatial representations and the temporal integration of individual items into episodic memories.
内嗅皮层是新皮层和海马体之间相互作用的主要门户。海马结构的不同区域、层和细胞在出生后发育过程中表现出不同的结构和分子成熟特征。在这里，我们提供了猴内嗅皮层（Eo、Er、Elr、Ei、Elc、Ec、Ecl）在出生后发育过程中神经元数量、神经元胞体大小和不同层及细分的体积的估计值。我们发现不同的细分区域中不同层的神经元胞体大小和体积有不同的发育变化，但神经元数量没有变化。大多数细分区域的 I 层和 II 层发育较早。Ec 和 Ecl 的 III 层表现出早期成熟，Ei 的 III 层表现出两步/早期成熟，Er 的 III 层表现出晚期成熟。Ec 和 Ecl 的 V 层和 VI 层表现出早期成熟，Ei 的 V 层和 VI 层表现出两步和早期成熟，Er 的 V 层和 VI 层表现出晚期成熟。神经元胞体大小在 6 个月时短暂增加，随后减少至成年大小，除了 Ei 的 II 层，以及 Ec 和 Ecl 的 II 层和 III 层。这些发现支持了不同海马体回路表现出不同发育特征的理论，这可能有助于不同海马体依赖的记忆过程的出现。我们讨论了尾侧内嗅皮层的早期成熟如何有助于路径整合和基本的非定域空间处理，而头侧内嗅皮层的晚期成熟如何有助于非定域空间表示的精度提高和将单个项目临时整合到情节记忆中。
