Shafer Andrea T, Dolcos Florin
Centre for Neuroscience, University of Alberta Edmonton, AB, Canada.
Centre for Neuroscience, University of Alberta Edmonton, AB, Canada ; Social, Cognitive, Personality, and Emotional Neuroscience Laboratory, Psychology Department, Neuroscience Program, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign IL, USA.
Front Behav Neurosci. 2014 Jun 3;8:177. doi: 10.3389/fnbeh.2014.00177. eCollection 2014.
The memory-enhancing effect of emotion has been linked to the engagement of emotion- and memory-related medial temporal lobe (MTL) regions (amygdala-AMY; hippocampus-HC; parahippocampus-PHC), during both encoding and retrieval. However, recognition tasks used to investigate the neural correlates of retrieval make it difficult to distinguish MTL engagement linked to retrieval success (RS) from that linked to incidental encoding success (ES) during retrieval. This issue has been investigated for retrieval of non-emotional memories, but not for emotional memory retrieval. To address this, we used event-related functional MRI in conjunction with an emotional distraction and two episodic memory tasks (one testing memory for distracter items and the other testing memory for new/lure items presented in the first memory task). This paradigm allowed for dissociation of MTL activity specifically linked to RS from that linked to both RS and incidental ES during retrieval. There were two novel findings regarding the neural correlates of emotional memory retrieval. First, greater emotional RS was identified bilaterally in AMY, HC, and PHC. However, AMY activity was most impacted when accounting for ES activity, as only RS activity in left AMY was dissociated from ES activity during retrieval, whereas portions of HC and PHC showing greater emotional RS were largely uninvolved in ES. Second, an earlier and more anteriorly spread response (left AMY and bilateral HC, PHC) was linked to greater emotional RS activity, whereas a later and more posteriorly localized response (right posterior PHC) was linked to greater neutral RS activity. These findings shed light on MTL mechanisms subserving the memory-enhancing effect of emotion at retrieval.
情绪的记忆增强效应与情绪和记忆相关的内侧颞叶（MTL）区域（杏仁核 - AMY；海马体 - HC；海马旁回 - PHC）在编码和检索过程中的参与有关。然而，用于研究检索神经相关性的识别任务使得在检索过程中难以区分与检索成功（RS）相关的MTL参与和与偶然编码成功（ES）相关的MTL参与。这个问题已经在非情绪记忆检索中进行了研究，但尚未在情绪记忆检索中进行研究。为了解决这个问题，我们使用了事件相关功能磁共振成像，并结合了情绪分心和两个情景记忆任务（一个测试对分心项目的记忆，另一个测试对在第一个记忆任务中呈现的新/诱饵项目的记忆）。这种范式允许在检索过程中，将与RS特异性相关的MTL活动与与RS和偶然ES都相关的MTL活动区分开来。关于情绪记忆检索的神经相关性有两个新发现。首先，在双侧的AMY、HC和PHC中都发现了更强的情绪RS。然而，在考虑ES活动时，AMY的活动受到的影响最大，因为在检索过程中，只有左AMY中的RS活动与ES活动分离，而显示出更强情绪RS的HC和PHC部分在很大程度上与ES无关。其次，更早且更向前扩散的反应（左AMY和双侧HC、PHC）与更强的情绪RS活动相关，而更晚且更向后定位的反应（右后PHC）与更强的中性RS活动相关。这些发现揭示了MTL机制在检索时对情绪记忆增强效应的支持作用。
