Thakral Preston P, Wang Tracy H, Rugg Michael D
Department of Psychology, Harvard University, USA.
Department of Psychology, University of Texas at Austin, USA.
Cortex. 2017 Jun;91:101-113. doi: 10.1016/j.cortex.2016.12.011. Epub 2016 Dec 22.
Recollection - retrieval of qualitative information about a past event - is associated with enhanced neural activity in a consistent set of neural regions (the 'core recollection network') seemingly regardless of the nature of the recollected content. Here, we employed multi-voxel pattern analysis (MVPA) to assess whether retrieval-related functional magnetic resonance imaging (fMRI) activity in core recollection regions - including the hippocampus, angular gyrus, medial prefrontal cortex, retrosplenial/posterior cingulate cortex, and middle temporal gyrus - contain information about studied content and thus demonstrate retrieval-related 'reinstatement' effects. During study, participants viewed objects and concrete words that were subjected to different encoding tasks. Test items included studied words, the names of studied objects, or unstudied words. Participants judged whether the items were recollected, familiar, or new by making 'remember', 'know', and 'new' responses, respectively. The study history of remembered test items could be reliably decoded using MVPA in most regions, as well as from the dorsolateral prefrontal cortex, a region where univariate recollection effects could not be detected. The findings add to evidence that members of the core recollection network, as well as at least one neural region where mean signal is insensitive to recollection success, carry information about recollected content. Importantly, the study history of recognized items endorsed with a 'know' response could be decoded with equal accuracy. The results thus demonstrate a striking dissociation between mean signal and multi-voxel indices of recollection. Moreover, they converge with prior findings in suggesting that, as it is operationalized by classification-based MVPA, reinstatement is not uniquely a signature of recollection.
回忆——对过去事件定性信息的提取——似乎与一组一致的神经区域（“核心回忆网络”）中增强的神经活动相关，而与所回忆内容的性质无关。在这里，我们采用多体素模式分析（MVPA）来评估核心回忆区域（包括海马体、角回、内侧前额叶皮质、压后皮质/后扣带回皮质和颞中回）中与提取相关的功能磁共振成像（fMRI）活动是否包含有关所学内容的信息，从而证明与提取相关的“恢复”效应。在学习过程中，参与者观看了接受不同编码任务的物体和具体单词。测试项目包括所学单词、所学物体的名称或未学单词。参与者分别通过做出“记得”“知道”和“新的”反应来判断这些项目是被回忆起来的、熟悉的还是新的。使用MVPA可以在大多数区域以及背外侧前额叶皮质可靠地解码被回忆起的测试项目的学习历史，而在该区域单变量回忆效应无法被检测到。这些发现进一步证明，核心回忆网络的成员以及至少一个平均信号对回忆成功不敏感的神经区域携带有关被回忆内容的信息。重要的是，以“知道”反应认可的被识别项目的学习历史可以以相同的准确性被解码。因此，结果表明平均信号与回忆的多体素指标之间存在显著分离。此外，它们与先前的研究结果一致，表明如基于分类的MVPA所实施的那样，恢复并非回忆所独有的特征。
