Department of Psychology, University of Arizona, Tucson, Arizona 85724, USA.
Learn Mem. 2012 Feb 17;19(3):91-8. doi: 10.1101/lm.023408.111.
There is strong evidence that reactivation of a memory returns it to a labile state, initiating a restabilization process termed reconsolidation, which allows for updating of the memory. In this study we investigated reactivation-dependent updating using a new positively motivated spatial task in rodents that was designed specifically to model a human list-learning paradigm. On Day 1, rats were trained to run to three feeders (List 1) for rewards. On Day 2, rats were trained to run to three different feeders (List 2) in either the same (Reminder condition) or a different (No Reminder condition) experimental context than on Day 1. On Day 3, rats were cued to recall List 1. Rats in the Reminder condition made significantly more visits to List 2 feeders (intrusions) during List 1 recall than rats in the No Reminder condition, indicating that the reminder triggered reactivation and allowed integration of List 2 items into List 1. This reminder effect was selective for the reactivated List 1 memory, as no intrusions occurred when List 2 was recalled on Day 3. No intrusions occurred when retrieval took place in a different context from the one used at encoding, indicating that the expression of the updated memory is dependent upon the retrieval context. Finally, the level of intrusions was highest when retrieval took place immediately after List 2 learning, and generally declined when retrieval occurred 1-4 h later, indicating that the List 2 memory competed with short-term retrieval of List 1. These results demonstrate the dynamic nature of memory over time and the impact of environmental context at different stages of memory processing.
有强有力的证据表明，记忆的再激活会使其回到不稳定状态，从而启动一个称为再巩固的重新稳定过程，这允许对记忆进行更新。在这项研究中，我们使用一种新的正激励空间任务在啮齿动物中研究了再激活依赖性更新，该任务专门设计用于模拟人类列表学习范式。在第 1 天，老鼠接受训练，跑到三个饲料器（列表 1）获取奖励。在第 2 天，老鼠接受训练，在与第 1 天相同（提醒条件）或不同（无提醒条件）的实验环境中跑到三个不同的饲料器（列表 2）。在第 3 天，老鼠被提示回忆列表 1。在提醒条件下，老鼠在回忆列表 1 时，会明显更多地访问列表 2 饲料器（闯入），而在无提醒条件下，老鼠则不会，这表明提醒触发了再激活，并允许将列表 2 项目整合到列表 1 中。这种提醒效应是针对被重新激活的列表 1 记忆的，因为在第 3 天回忆列表 2 时没有闯入。当检索发生在与编码时不同的上下文时，不会发生闯入，这表明更新后的记忆的表达依赖于检索上下文。最后，当检索发生在学习列表 2 后立即进行时，闯入的水平最高，当检索发生在 1-4 小时后时，闯入的水平通常会下降，这表明列表 2 记忆与列表 1 的短期检索竞争。这些结果表明记忆随着时间的推移具有动态性质，并且环境上下文在记忆处理的不同阶段都有影响。
