It is well known that distributed learning (DL) leads to improved memory performance compared with massed learning (ML) (i.e., spacing effect). However, the extent to which the hippocampus is involved in the spacing effect at shorter and longer retention intervals remains unclear. To address this issue, two groups of participants were asked to encode face–scene pairs at 20‐min, 1‐day, and 1‐month intervals before they were scanned using fMRI during an associative recognition task. The pairs were repeated six times in either a massed (i.e., six times in 1 day) or a distributed (i.e., six times over 3 days, twice per day) manner. The results showed that compared with that in the ML group, the activation of the left hippocampus was stronger in the DL group when the participants retrieved old pairs correctly and rejected new pairs correctly at different retention intervals. In addition, the posterior hippocampus was more strongly activated when the new associations were rejected correctly after DL than ML, especially at the 1‐month interval. Hence, our results provide evidence that the hippocampus is involved in better memory performance after DL compared to ML at both shorter and longer retention intervals.

中文翻译：

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海马体在记忆提取过程中间隔效应中的作用。

众所周知，与集中学习（ML）（即间隔效应）相比，分布式学习（DL）可以提高记忆性能。然而，海马体在更短和更长的保留间隔中参与间隔效应的程度仍不清楚。为了解决这个问题，在关联识别任务期间使用 fMRI 扫描之前，要求两组参与者以 20 分钟、1 天和 1 个月的间隔对面部场景对进行编码。以集中（即1 天内6 次）或分布式（即3 天内6 次，每天2 次）的方式将这些对重复6 次。结果显示，与ML组相比，当参与者以不同的保留间隔正确检索旧对并正确拒绝新对时，DL 组左侧海马体的激活更强。此外，与 ML 相比，DL 后正确拒绝新关联时，后海马体被更强烈地激活，尤其是在 1 个月的时间间隔内。因此，我们的结果提供证据表明，与 ML 相比，在更短和更长的保留间隔下，海马体在 DL 后具有更好的记忆性能。