de Zubicaray Greig I, McMahon Katie L, Eastburn Matthew M, Finnigan Simon, Humphreys Michael S
Centre for Magnetic Resonance, The University of Queensland, QLD 4072, Australia.
Brain Res Cogn Brain Res. 2005 Aug;24(3):587-98. doi: 10.1016/j.cogbrainres.2005.03.009. Epub 2005 Apr 19.
We used event-related fMRI to investigate the neural correlates of encoding strength and word frequency effects in recognition memory. At test, participants made Old/New decisions to intermixed low (LF) and high frequency (HF) words that had been presented once or twice at study and to new, unstudied words. The Old/New effect for all hits vs. correctly rejected unstudied words was associated with differential activity in multiple cortical regions, including the anterior medial temporal lobe (MTL), hippocampus, left lateral parietal cortex and anterior left inferior prefrontal cortex (LIPC). Items repeated at study had superior hit rates (HR) compared to items presented once and were associated with reduced activity in the right anterior MTL. By contrast, other regions that had shown conventional Old/New effects did not demonstrate modulation according to memory strength. A mirror effect for word frequency was demonstrated, with the LF word HR advantage associated with increased activity in the left lateral temporal cortex. However, none of the regions that had demonstrated Old/New item retrieval effects showed modulation according to word frequency. These findings are interpreted as supporting single-process memory models proposing a unitary strength-like memory signal and models attributing the LF word HR advantage to the greater lexico-semantic context-noise associated with HF words due to their being experienced in many pre-experimental contexts.
我们使用事件相关功能磁共振成像技术来研究识别记忆中编码强度和词频效应的神经关联。在测试阶段，参与者对在学习阶段呈现过一次或两次的低频（LF）和高频（HF）单词以及新的、未学习过的单词做出“旧/新”判断。所有命中项与正确拒绝的未学习单词之间的“旧/新”效应与多个皮质区域的差异活动相关，包括前内侧颞叶（MTL）、海马体、左侧顶叶外侧皮质和左侧前额叶下回（LIPC）。与只呈现过一次的项目相比，在学习阶段重复呈现的项目有更高的命中率（HR），并且与右侧前MTL活动减少有关。相比之下，其他显示出传统“旧/新”效应的区域并未根据记忆强度表现出调节作用。我们发现了词频的镜像效应，低频词的HR优势与左侧颞叶外侧皮质活动增加有关。然而，所有显示出“旧/新”项目检索效应的区域均未根据词频表现出调节作用。这些发现被解释为支持单进程记忆模型，该模型提出了一种单一的类似强度的记忆信号，以及将低频词的HR优势归因于高频词因在许多实验前情境中出现而具有更大的词汇-语义上下文噪声的模型。
