Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey 08540, USA.
J Neurosci. 2012 Jun 27;32(26):8871-8. doi: 10.1523/JNEUROSCI.5321-11.2012.
Although it is well established that remembering an item will bring to mind memories of other semantically related items (Bousfield, 1953), the neural basis of this phenomenon is poorly understood. We studied how the similarity relations among items influence their retrieval by analyzing electrocorticographic recordings taken as 46 human neurosurgical patients studied and freely recalled lists of words. We first identified semantic components of neural activity that varied systematically with the meanings of each studied word, as defined by latent semantic analysis (Landauer and Dumais, 1997). We then examined the dynamics of these semantic components as participants attempted to recall the previously studied words. Our analyses revealed that the semantic components of neural activity were spontaneously reactivated during memory search, just before recall of the studied words. Further, the degree to which neural activity correlated with semantic similarity during recall predicted participants' tendencies to organize the sequences of their responses on the basis of semantic similarity. Thus, our work shows that differences in the neural correlates of semantic information, and how they are reactivated before recall, reveal how individuals organize and retrieve memories of words.
虽然人们已经充分认识到，记住一个项目会唤起对其他语义相关项目的记忆（Bousfield，1953），但这一现象的神经基础仍知之甚少。我们通过分析 46 名接受神经外科治疗的患者在自由回忆单词列表时的脑电图记录，研究了项目之间的相似关系如何影响它们的检索。我们首先确定了神经活动的语义成分，这些成分与每个学习单词的含义（由潜在语义分析定义）系统地变化（Landauer 和 Dumais，1997）。然后，我们研究了参与者试图回忆之前学习过的单词时这些语义成分的动态。我们的分析表明，在记忆搜索过程中，即在回忆学习单词之前，神经活动的语义成分会自发地重新激活。此外，在回忆过程中，神经活动与语义相似性的相关程度预测了参与者根据语义相似性组织反应序列的倾向。因此，我们的工作表明，语义信息的神经相关性的差异，以及它们在回忆前是如何重新激活的，揭示了个体如何组织和检索单词的记忆。
