Data from: Hippocampal neurogenesis regulates forgetting during adulthood and infancy

Throughout life, new neurons are continuously added to the dentate gyrus. As this continuous addition remodels hippocampal circuits, computational models predict that neurogenesis leads to degradation or forgetting of established memories. Consistent with this, increasing neurogenesis after the formation of a memory was sufficient to induce forgetting in adult mice. By contrast, during infancy, when hippocampal neurogenesis levels are high and freshly-generated memories tend to be rapidly forgotten (infantile amnesia), decreasing neurogenesis after memory formation mitigated forgetting. In precocial species, including guinea pigs and degus, the majority of granule cells are generated prenatally. Consistent with reduced levels of postnatal hippocampal neurogenesis, infant guinea pigs and degus did not exhibit forgetting. However, increasing neurogenesis after memory formation induced infantile amnesia in these species.在整个生命周期中，新神经元会持续添加至齿状回（dentate gyrus）。由于该持续的神经元生成过程会重塑海马环路，计算模型预测神经发生（neurogenesis）会导致已建立记忆的降解或遗忘。与此一致的是，在记忆形成后增加神经发生，足以诱导成年小鼠产生遗忘。与之形成对比的是，在婴儿期，当海马神经发生水平较高且新生成的记忆易于快速遗忘（婴儿期遗忘（infantile amnesia））时，在记忆形成后降低神经发生可缓解遗忘。在早熟性物种（包括豚鼠与八齿鼠）中，绝大多数颗粒细胞于产前生成。这与产后海马神经发生水平降低的情况相符，幼年豚鼠和八齿鼠并未表现出遗忘现象。然而，在记忆形成后增加神经发生，会在这些物种中诱导出婴儿期遗忘。