Laboratory of Brain and Cognitive Development, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland.
J Comp Neurol. 2011 Apr 15;519(6):1051-70. doi: 10.1002/cne.22549.
We performed a stereological analysis of neuron number, neuronal soma size, and volume of individual regions and layers of the macaque monkey hippocampal formation during early postnatal development. We found a protracted period of neuron addition in the dentate gyrus throughout the first postnatal year and a concomitant late maturation of the granule cell population and individual dentate gyrus layers that extended beyond the first year of life. Although the development of CA3 generally paralleled that of the dentate gyrus, the distal portion of CA3, which receives direct entorhinal cortex projections, matured earlier than the proximal portion of CA3. CA1 matured earlier than the dentate gyrus and CA3. Interestingly, CA1 stratum lacunosum-moleculare, in which direct entorhinal cortex projections terminate, matured earlier than CA1 strata oriens, pyramidale, and radiatum, in which the CA3 projections terminate. The subiculum developed earlier than the dentate gyrus, CA3, and CA1, but not CA2. However, similarly to CA1, the molecular layer of the subiculum, in which the entorhinal cortex projections terminate, was overall more mature in the first postnatal year compared with the stratum pyramidale in which most of the CA1 projections terminate. Unlike other hippocampal fields, volumetric measurements suggested regressive events in the structural maturation of presubicular neurons and circuits. Finally, areal and neuron soma size measurements revealed an early maturation of the parasubiculum. We discuss the functional implications of the differential development of distinct hippocampal circuits for the emergence and maturation of different types of "hippocampus-dependent" memory processes, including spatial and episodic memories.
我们对猕猴海马结构在出生后早期发育过程中的神经元数量、神经元胞体大小以及各个区域和层的体积进行了体视学分析。我们发现，齿状回在出生后的第一年中持续存在神经元的大量增加，而颗粒细胞群体和单独的齿状回层的成熟则较晚，持续到生命的第一年之后。虽然 CA3 的发育总体上与齿状回相似，但接受直接内嗅皮层投射的 CA3 的远端部分比 CA3 的近端部分更早成熟。CA1 的成熟早于齿状回和 CA3。有趣的是，CA1 的腔隙分子层（其中直接接受内嗅皮层投射）比 CA1 的始层、锥体层和辐射层成熟得更早，而 CA3 的投射终止于 CA1 的这些层。下托比齿状回、CA3 和 CA1 发育得更早，但不比 CA2 早。然而，与 CA1 相似，下托的分子层（其中终止内嗅皮层投射）在出生后的第一年比终止大部分 CA1 投射的锥体层更为成熟。与其他海马区不同，体积测量表明，在浦肯野细胞神经元和回路的结构成熟过程中存在退行性事件。最后，区域和神经元胞体大小的测量显示，旁海马体的早期成熟。我们讨论了不同海马回路的不同发育对不同类型的“海马依赖”记忆过程（包括空间和情景记忆）的出现和成熟的功能意义。
