Kim Hongkeun, Cabeza Roberto
Department of Rehabilitation Psychology, Daegu University, Daegu 705-714, South Korea.
J Neurosci. 2007 Nov 7;27(45):12190-7. doi: 10.1523/JNEUROSCI.3408-07.2007.
Although memory confidence and accuracy tend to be positively correlated, people sometimes remember with high confidence events that never happened. How can confidence correlate with accuracy but apply also to illusory memories? One possible explanation is that high confidence in veridical versus illusory memories depends on different neural mechanisms. The present study investigated this possibility using functional magnetic resonance imaging and a modified version of the Deese-Roediger-McDermott false-memory paradigm. Participants read short lists of categorized words, and brain activity was measured while they performed a recognition test with confidence rating. The study yielded three main findings. First, compared with low-confidence responses, high-confidence responses were associated with medial temporal lobe (MTL) activity in the case of true recognition but with frontoparietal activity in the case of false recognition. Second, these regions showed significant confidence-by-veridicality interactions. Finally, only MTL regions showed greater activity for high-confidence true recognition than for high-confidence false recognition, and only frontoparietal regions showed greater activity for high-confidence false recognition than for high-confidence true recognition. These findings indicate that confidence in true recognition is mediated primarily by a recollection-related MTL mechanism, whereas confidence in false recognition reflects mainly a familiarity-related frontoparietal mechanism. This account is consistent with the fuzzy trace theory of false recognition. Correlation analyses revealed that MTL and frontoparietal regions play complementary roles during episodic retrieval. In sum, the present study shows that when one focuses exclusively on high-confidence responses, the neural correlates of true and false memory are clearly different.
尽管记忆信心与准确性往往呈正相关，但人们有时会对从未发生过的事件充满信心地进行回忆。信心如何能与准确性相关，却又适用于虚假记忆呢？一种可能的解释是，对真实记忆与虚假记忆的高度信心取决于不同的神经机制。本研究使用功能磁共振成像以及改良版的迪斯-罗迪格-麦克德莫特虚假记忆范式来探究这种可能性。参与者阅读分类单词的简短列表，并在他们进行带有信心评级的识别测试时测量大脑活动。该研究产生了三个主要发现。首先，与低信心反应相比，在真实识别情况下，高信心反应与内侧颞叶（MTL）活动相关，而在虚假识别情况下，与额顶叶活动相关。其次，这些区域显示出显著的信心与真实性交互作用。最后，只有MTL区域在高信心真实识别时比高信心虚假识别时表现出更强的活动，并且只有额顶叶区域在高信心虚假识别时比高信心真实识别时表现出更强的活动。这些发现表明，对真实识别的信心主要由与回忆相关的MTL机制介导，而对虚假识别的信心主要反映与熟悉度相关的额顶叶机制。这一解释与虚假识别的模糊痕迹理论一致。相关性分析表明，MTL和额顶叶区域在情景检索过程中发挥互补作用。总之，本研究表明，当仅关注高信心反应时，真实记忆和虚假记忆的神经关联明显不同。
