Department of Physiology, The University of Tokyo School of Medicine, Tokyo, Japan.
PLoS One. 2013 Aug 29;8(8):e71210. doi: 10.1371/journal.pone.0071210. eCollection 2013.
Episodic memory retrieval most often recruits multiple separate processes that are thought to involve different temporal regions. Previous studies suggest dissociable regions in the left lateral parietal cortex that are associated with the retrieval processes. Moreover, studies using resting-state functional connectivity (RSFC) have provided evidence for the temporo-parietal memory networks that may support the retrieval processes. In this functional MRI study, we tested functional significance of the memory networks by examining functional connectivity of brain activity during episodic retrieval in the temporal and parietal regions of the memory networks. Recency judgments, judgments of the temporal order of past events, can be achieved by at least two retrieval processes, relational and item-based. Neuroimaging results revealed several temporal and parietal activations associated with relational/item-based recency judgments. Significant RSFC was observed between one parahippocampal region and one left lateral parietal region associated with relational recency judgments, and between four lateral temporal regions and another left lateral parietal region associated with item-based recency judgments. Functional connectivity during task was found to be significant between the parahippocampal region and the parietal region in the RSFC network associated with relational recency judgments. However, out of the four tempo-parietal RSFC networks associated with item-based recency judgments, only one of them (between the left posterior lateral temporal region and the left lateral parietal region) showed significant functional connectivity during task. These results highlight the contrasting roles of the parahippocampal and the lateral temporal regions in recency judgments, and suggest that only a part of the tempo-parietal RSFC networks are recruited to support particular retrieval processes.
情景记忆检索通常会调用多个独立的过程，这些过程被认为涉及不同的时间区域。先前的研究表明，左侧顶叶皮层的分离区域与检索过程有关。此外，使用静息态功能连接（RSFC）的研究为可能支持检索过程的颞顶记忆网络提供了证据。在这项功能磁共振成像研究中，我们通过检查记忆网络中颞叶和顶叶区域在情景记忆检索过程中的脑活动功能连接，来测试记忆网络的功能意义。最近事件判断，即对过去事件时间顺序的判断，可以通过至少两种检索过程，即关系和项目基础来实现。神经影像学结果揭示了与关系/项目基础最近事件判断相关的几个颞叶和顶叶激活。在与关系最近事件判断相关的 RSFC 网络中，观察到一个海马旁区域和一个左侧顶叶区域之间存在显著的 RSFC，以及四个外侧颞叶区域和另一个与项目基础最近事件判断相关的左侧顶叶区域之间存在显著的 RSFC。在任务期间发现，在与关系最近事件判断相关的 RSFC 网络中，海马旁区域和顶叶区域之间的功能连接是显著的。然而，在与项目基础最近事件判断相关的四个颞顶 RSFC 网络中，只有一个（在左侧后外侧颞叶区域和左侧顶叶区域之间）在任务期间显示出显著的功能连接。这些结果突出了海马旁区域和外侧颞叶在最近事件判断中的对比作用，并表明只有颞顶 RSFC 网络的一部分被招募来支持特定的检索过程。
