Woodruff C Chad, Johnson Jeffrey D, Uncapher Melina R, Rugg Michael D
Center for the Neurobiology of Learning and Memory, and Department of Neurobiology and Behavior, University of California, Irvine, CA 92697, USA.
Neuropsychologia. 2005;43(7):1022-32. doi: 10.1016/j.neuropsychologia.2004.10.013. Epub 2005 Jan 24.
It is widely assumed that episodic retrieval (recollection) involves reinstatement of cortical activity engaged during the processing of an episode when it was initially experienced. It follows from this assumption that the cortical correlates of recollection should differ with the content of what is recollected, and that retrieval of different content should be associated with activity in functionally distinct cortical regions. The present experiment investigated these predictions. Subjects (N=17) studied a mixed list of words and pictures and were then presented with a test list comprised of words only. Test items were studied words, the names of studied pictures, and unstudied (new) words. Functional magnetic resonance images were acquired while the subjects made Remember/Know/New judgments to these test words. Independent of study material, studied items endorsed as Remembered elicited greater activity than correctly classified unstudied items in several regions, including left frontal, left lateral parietal, and posterior cingulate cortex. In addition, Remembered items elicited greater activity in the right hippocampus and parahippocampal gyrus than items accorded Know judgments, replicating previous findings. Analysis of content-specific effects demonstrated a regional double-dissociation within left fusiform cortex; recollected words elicited greater activity than recollected pictures in lateral fusiform, whereas the reverse effect was evident in an anterior fusiform region. The lateral and anterior fusiform areas correspond closely to areas held to be functionally specialized for the processing of visual words and pictures, respectively. Thus, the current findings support the cortical reinstatement hypothesis of episodic retrieval.
人们普遍认为，情景记忆提取（回忆）涉及到在最初经历某个情景时所参与的皮层活动的恢复。基于这一假设可以推断，回忆的皮层相关物应该会因所回忆内容的不同而有所差异，并且不同内容的提取应该与功能上不同的皮层区域的活动相关联。本实验对这些预测进行了研究。受试者（N = 17）学习了一个由单词和图片组成的混合列表，然后呈现给他们一个仅由单词组成的测试列表。测试项目包括学过的单词、学过图片的名称以及未学过的（新）单词。在受试者对这些测试单词做出“记得/知道/新”判断时，采集功能磁共振图像。与学习材料无关，被判定为“记得”的学过项目在包括左额叶、左侧顶叶和后扣带回皮层在内的几个区域引发的活动比正确分类的未学过项目更强烈。此外，与被判定为“知道”的项目相比，被判定为“记得”的项目在右侧海马体和海马旁回引发的活动更强烈，这重复了之前的研究结果。对内容特异性效应的分析表明，在左侧梭状回内存在区域双重分离；在梭状回外侧，回忆起的单词引发的活动比回忆起的图片更强烈，而在梭状回前部区域则出现相反的效应。梭状回外侧和前部区域分别与被认为在功能上专门用于处理视觉单词和图片的区域紧密对应。因此，当前的研究结果支持情景记忆提取的皮层恢复假说。
