Center for Cognitive Neuroscience, Duke University, Durham, North Carolina 27708, USA.
J Neurosci. 2013 Sep 4;33(36):14466-74. doi: 10.1523/JNEUROSCI.1413-13.2013.
Although it is well established that the perirhinal cortex (PRC) makes an important contribution to recognition memory, the specific nature of this contribution remains uncertain. The finding that PRC activity is reduced for old compared with new items is typically attributed to the recovery of a long-term memory (LTM) signal. However, because old items are processed more easily or fluently than new items, reduced PRC activity could reflect increased fluency rather than LTM retrieval per se. We tested this hypothesis in humans using fMRI and a well-validated method to manipulate fluency: the masked priming paradigm. Some words during an old-new recognition test were preceded by conceptually related words (primes) that were subliminally presented (masked). The behavioral results replicated previous findings using this paradigm, whereby the fluency manipulation increased "oldness" responses to both old and new items. The fMRI analyses yielded two main sets of results. First, in the case of new items, which are independent from LTM retrieval, masked priming reduced PRC activity and predicted behavioral misattribution of fluency to oldness. Second, in the case of old items, the same PRC region showing fluency-related reductions for new items also contributed to "old" responding to old items. Individual differences in PRC attenuation also predicted oldness ratings to old items, and fluency modulated PRC connectivity with other brain regions associated with processing oldness signals, including visual cortex and right lateral prefrontal cortex. These results support a broader view in which the PRC serves a function more general than memory.
虽然已经证实，边缘系统（PRC）对识别记忆有重要贡献，但这种贡献的具体性质仍不确定。与新物品相比，PRC 活动减少的发现通常归因于长期记忆（LTM）信号的恢复。然而，由于旧物品比新物品更容易或更流畅地被处理，因此 PRC 活动的减少可能反映了流畅度的增加，而不是 LTM 检索本身。我们使用 fMRI 和一种经过充分验证的操纵流畅度的方法——掩蔽启动范式在人类中测试了这一假设。在旧新识别测试中，一些单词之前会出现概念上相关的单词（启动词），这些单词是在潜意识中呈现的（掩蔽）。行为结果复制了使用该范式的先前发现，即流畅度的操纵增加了对新旧物品的“旧”反应。 fMRI 分析产生了两组主要结果。首先，在新物品的情况下，新物品与 LTM 检索无关，掩蔽启动减少了 PRC 活动，并预测了行为上对流畅度的错误归因。其次，在旧物品的情况下，对于新物品，表现出与流畅性相关减少的相同 PRC 区域也有助于对旧物品的“旧”反应。PRC 衰减的个体差异也预测了对旧物品的旧度评分，并且流畅度调节了 PRC 与其他与处理旧度信号相关的大脑区域（包括视觉皮层和右侧前额叶皮层）的连接。这些结果支持了一种更广泛的观点，即 PRC 具有比记忆更普遍的功能。
