Koen Joshua D, Rugg Michael D
Center for Vital Longevity and School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75235
Center for Vital Longevity and School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75235.
J Neurosci. 2016 Apr 13;36(15):4389-99. doi: 10.1523/JNEUROSCI.4099-15.2016.
Memory reactivation--the reinstatement of processes and representations engaged when an event is initially experienced--is believed to play an important role in strengthening and updating episodic memory. The present study examines how memory reactivation during a potentially interfering event influences memory for a previously experienced event. Participants underwent fMRI during the encoding phase of an AB/AC interference task in which some words were presented twice in association with two different encoding tasks (AB and AC trials) and other words were presented once (DE trials). The later memory test required retrieval of the encoding tasks associated with each of the study words. Retroactive interference was evident for the AB encoding task and was particularly strong when the AC encoding task was remembered rather than forgotten. We used multivariate classification and pattern similarity analysis (PSA) to measure reactivation of the AB encoding task during AC trials. The results demonstrated that reactivation of generic task information measured with multivariate classification predicted subsequent memory for the AB encoding task regardless of whether interference was strong and weak (trials for which the AC encoding task was remembered or forgotten, respectively). In contrast, reactivation of neural patterns idiosyncratic to a given AB trial measured with PSA only predicted memory when the strength of interference was low. These results suggest that reactivation of features of an initial experience shared across numerous events in the same category, but not features idiosyncratic to a particular event, are important in resisting retroactive interference caused by new learning.
Reactivating a previously encoded memory is believed to provide an opportunity to strengthen the memory, but also to return the memory to a labile state, making it susceptible to interference. However, there is debate as to how memory reactivation elicited by a potentially interfering event influences subsequent retrieval of the memory. The findings of the current study indicate that reactivating features idiosyncratic to a particular experience during interference only influences subsequent memory when interference is relatively weak. Critically, reactivation of generic contextual information predicts subsequent source memory when retroactive interference is either strong and weak. The results indicate that reactivation of generic information about a prior episode mitigates forgetting due to retroactive interference.
记忆再激活——即重新激活事件初次经历时所涉及的过程和表征——被认为在强化和更新情景记忆中发挥着重要作用。本研究考察了在一个可能产生干扰的事件期间的记忆再激活如何影响对先前经历事件的记忆。参与者在AB/AC干扰任务的编码阶段接受功能磁共振成像（fMRI），在该任务中，一些单词与两个不同的编码任务（AB和AC试验）相关联地呈现两次，而其他单词只呈现一次（DE试验）。随后的记忆测试要求检索与每个学习单词相关的编码任务。AB编码任务存在明显的倒摄干扰，当AC编码任务被记住而非遗忘时，这种干扰尤为强烈。我们使用多变量分类和模式相似性分析（PSA）来测量AC试验期间AB编码任务的再激活。结果表明，无论干扰强弱（分别对应AC编码任务被记住或遗忘的试验），用多变量分类测量的一般任务信息的再激活都能预测随后对AB编码任务的记忆。相比之下，用PSA测量的特定AB试验特有的神经模式的再激活仅在干扰强度较低时预测记忆。这些结果表明，在同一类别中跨多个事件共享的初始经历特征的再激活，而非特定事件特有的特征，对于抵抗新学习引起的倒摄干扰很重要。
重新激活先前编码的记忆被认为既能提供强化记忆的机会，也会使记忆回到不稳定状态，使其容易受到干扰。然而，关于由一个可能产生干扰的事件引发的记忆再激活如何影响随后的记忆检索存在争议。当前研究的结果表明，在干扰期间重新激活特定经历特有的特征仅在干扰相对较弱时影响随后的记忆。关键的是，无论倒摄干扰强弱，一般情境信息的再激活都能预测随后的源记忆。结果表明，关于先前事件的一般信息的再激活减轻了由倒摄干扰导致的遗忘。
