When less means more: deactivations during encoding that predict subsequent memory
When less means more: deactivations during encoding that predict subsequent memory
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DOI：
10.1016/j.neuroimage.2004.07.031
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发表时间：
2004-11-01
期刊：
影响因子：
5.7
通讯作者：
Cabeza, R
中科院分区：
文献类型：
--
作者：
Daselaar, SM;Prince, SE;Cabeza, R
在事件相关的功能 MRI (fMRI) 研究中，随后记住的项目（R 项目）比随后忘记的项目（F 项目）更活跃，或 Din 效应（记忆差异）归因于成功的编码操作。相比之下，表现出反向 DM 效应的区域 (revDM = F-items > R-items) 与导致遗忘的有害过程有关。然而，revDM不仅可以反映F项（aFs）的激活，还可以反映R项（dRs）的停用，而后一种选择更可能反映有益的而不是有害的编码过程。为了研究这个问题，我们使用了一种范例，其中包括注视基线，并且可以区分两种类型的 revDM（aF 与 dR）。参与者在编码单词之间的语义关联或单词和字体之间的感知关联时被扫描，并通过联想识别测试来测量他们的记忆力。对于语义和知觉编码，dR 效应出现在背外侧前额叶、颞顶叶和后中线区域。与先前将这些区域的 revDM 归因于有害过程的研究相比，目前的结果表明这些影响反映了有益的过程，即神经认知资源的有效重新分配。与此同时，在其他区域也发现了房颤效应，例如岛叶，这些更符合有害过程的解释。虽然大多数编码的功能磁共振成像研究都集中在激活增加上，但本研究表明激活减少对于成功学习新信息也至关重要。 (C) 2004 Elsevier Inc. 保留所有权利。
In event-related functional MRI (fMRI) studies, greater activity for items that are subsequently remembered (R-items) than for items that are subsequently forgotten (F-items), or Din effect (Difference in memory), has been attributed to successful encoding operations. In contrast, regions showing a reverse DM effect (revDM = F-items > R-items) have been linked to detrimental processes leading to forgetting. Yet, revDMs may reflect not only activations for F-items (aFs) but also deactivations for R-items (dRs), and the latter alternative is more likely to reflect beneficial rather than detrimental encoding processes. To investigate this issue, we used a paradigm that included a fixation baseline and could distinguish between the two types of revDMs (aF vs. dR). Participants were scanned while encoding semantic associations between words or perceptual associations between words and fonts, and their memory was measured with associative recognition tests. For both semantic and perceptual encoding, dR effects were found in dorsolateral prefrontal, temporoparietal, and posterior midline regions. In contrast with a prior study that attributed revDMs in these regions to detrimental processes, the present results suggest that these effects reflect beneficial processes, that is, the efficient reallocation of neurocognitive resources. At the same time, aF effects were found in other regions, such as the insula, and these are more consistent with an interpretation in terms of detrimental processes. Whereas most fMRI studies of encoding have focused on activation increases, the present study indicates that activation decreases are also critical for successful learning of new information. (C) 2004 Elsevier Inc. All rights reserved.