Umeå University, Sweden.
J Cogn Neurosci. 2011 Apr;23(4):947-60. doi: 10.1162/jocn.2010.21494. Epub 2010 Mar 29.
Memories of past episodes frequently come to mind incidentally, without directed search. It has remained unclear how incidental retrieval processes are initiated in the brain. Here we used fMRI and ERP recordings to find brain activity that specifically correlates with incidental retrieval, as compared to intentional retrieval. Intentional retrieval was associated with increased activation in dorsolateral prefrontal cortex. By contrast, incidental retrieval was associated with a reduced fMRI signal in posterior brain regions, including extrastriate and parahippocampal cortex, and a modulation of a posterior ERP component 170 msec after the onset of visual retrieval cues. Successful retrieval under both intentional and incidental conditions was associated with increased activation in the hippocampus, precuneus, and ventrolateral prefrontal cortex, as well as increased amplitude of the P600 ERP component. These results demonstrate how early bottom-up signals from posterior cortex can lead to reactivation of episodic memories in the absence of strategic retrieval attempts.
过去的事件记忆常常会偶然浮现在脑海中，而无需刻意搜索。目前仍不清楚大脑中是如何启动偶然检索过程的。在这里，我们使用 fMRI 和 ERP 记录来寻找与偶然检索相关的大脑活动，与刻意检索进行对比。刻意检索与背外侧前额叶皮层的激活增加有关。相比之下，偶然检索与后脑部区域（包括外纹状体和海马旁回皮质）的 fMRI 信号减少以及在视觉检索线索出现后 170 毫秒时的后 ERP 成分的调制有关。在有意和无意条件下的成功检索都与海马体、后扣带回和腹外侧前额叶皮层的激活增加以及 P600 ERP 成分的振幅增加有关。这些结果表明，来自后皮质的早期自下而上的信号如何在没有策略性检索尝试的情况下导致情景记忆的重新激活。
