Department of Neurology and Neurosurgery, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada.
PLoS One. 2013 Sep 5;8(9):e73789. doi: 10.1371/journal.pone.0073789. eCollection 2013.
During episodic memory encoding, elaborative cognitive processing can improve later recall or recognition. While multiple studies examined the neural correlates of encoding strategies, few studies have explicitly focused on the self-initiation of elaborative encoding. Repetitive transcranial magnetic stimulation (rTMS), a method which can transiently disrupt neural activity, was administered during an associative encoding task. rTMS was either applied to the left dorsolateral prefrontal cortex (DLPFC) or to the vertex (a control region not involved in memory encoding) during presentation of pairs of words. Pairs could be semantically related or not related. Two encoding instructions were given, either cueing participants to analyze semantic relationships (cued condition), or to memorize the pair without any specific strategy cues (the self-initiated condition). Participants filled out a questionnaire regarding their use of memory strategies and performed a cued-recall task. We hypothesized that if the DLPFC plays a role in the self-initiation of elaborative encoding we would observe a reduction in memory performance in the self-initiated condition, particularly for related. We found a significant correlation between the effects of rTMS and strategy use, only in the self-initiated condition with related pairs. High strategy users showed reduced performance following DLPFC stimulation, while low strategy users tended to show increased recall following DLPFC stimulation during encoding. These results suggest the left DLPFC may be involved in the self-initiation of memory strategy use, and individuals may utilize different neural networks depending on their use of encoding strategies.
在情景记忆编码期间,精心的认知加工可以提高后续的回忆或识别能力。虽然有多项研究考察了编码策略的神经相关性,但很少有研究专门关注精心编码的自我启动。重复经颅磁刺激(rTMS)是一种可以暂时破坏神经活动的方法,在联想编码任务期间施加于左背外侧前额叶皮层(DLPFC)或顶点(不参与记忆编码的控制区域)。在呈现单词对时,可以施加 rTMS 要么是相关的,要么是不相关的。给予两种编码指令,要么提示参与者分析语义关系(提示条件),要么在没有任何特定策略提示的情况下记忆对(自我启动条件)。参与者填写了一份关于他们使用记忆策略的问卷,并进行了提示回忆任务。我们假设如果 DLPFC 在精心编码的自我启动中起作用,我们将观察到自我启动条件下记忆表现的下降,特别是对于相关的。我们发现 rTMS 的效果和策略使用之间存在显著相关性,仅在自我启动条件下与相关对相关。高策略使用者在 DLPFC 刺激后表现出降低的表现,而低策略使用者在 DLPFC 刺激期间在编码时往往表现出增加的回忆。这些结果表明,左 DLPFC 可能参与了记忆策略使用的自我启动,并且个体可能根据其编码策略的使用而利用不同的神经网络。