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首页> 外文期刊>Neuropsychologia >Explaining the encoding/retrieval flip: Memory-related deactivations and activations in the posteromedial cortex
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Explaining the encoding/retrieval flip: Memory-related deactivations and activations in the posteromedial cortex

机译：解释编码/检索翻转：与记忆有关的去激活和后内侧皮质的激活

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The posteromedial cortex (PMC) is strongly linked to episodic memory and age-related memory deficits. The PMC shows deactivations during a variety of demanding cognitive tasks as compared to passive baseline conditions and has been associated with the default-mode of the brain. Interestingly, the PMC exhibits opposite levels of functional MRI activity during encoding (learning) and retrieval (remembering), a pattern dubbed the encoding/retrieval flip (E/R-flip). Yet, the exact role of the PMC in memory function has remained unclear. This review discusses the possible neurofunctional and clinical significance of the E/R-flip pattern. Regarding neurofunctional relevance, we will review four hypotheses on PMC function: (1) the internal orienting account, (2) the self-referential processing account, (3) the reallocation account, and (4) the bottom-up attention account. None of these accounts seem to provide a complete explanation for the E/R-flip pattern in PMC. Regarding clinical relevance, we review work on aging and Alzheimer's disease, indicating that amyloid deposits within PMC, years before clinical memory deficits become apparent. High amyloid burden within PMC is associated with detrimental influences on memory encoding, in particular, the attenuation of beneficial PMC deactivations. Finally, we discuss functional subdivisions within PMC that help to provide a more precise picture of the variety of signals observed within PMC. Collective data from anatomical, task-related fMRI and resting-state studies all indicate that the PMC is composed of three main regions, the precuneus, retrosplenial, and posterior cingulate cortex, each with a distinct function. We will conclude with a summary of the findings and provide directions for future research.
机译：后内侧皮质（PMC）与情景记忆和与年龄相关的记忆缺陷密切相关。与被动基线条件相比，PMC在各种艰巨的认知任务中表现出失活，并且与大脑的默认模式有关。有趣的是，PMC在编码（学习）和检索（记忆）过程中表现出相反的功能MRI活动水平，这种模式被称为编码/检索翻转（E / R翻转）。然而，PMC在记忆功能中的确切作用仍不清楚。这篇评论讨论了E / R翻转模式可能的神经功能和临床意义。关于神经功能相关性，我们将回顾关于PMC功能的四个假设：（1）内部定向帐户，（2）自指处理帐户，（3）重新分配帐户，以及（4）自下而上的注意帐户。这些说明似乎都不能完全解释PMC中的E / R翻转模式。关于临床相关性，我们回顾了关于衰老和阿尔茨海默氏病的研究，表明在临床记忆缺陷变得明显之前数年，PMC内存在淀粉样蛋白沉积。 PMC中淀粉样蛋白的高负荷与记忆编码的有害影响有关，尤其是有益PMC失活的减弱。最后，我们讨论PMC中的功能细分，这些细分有助于提供PMC中观察到的各种信号的更精确的图像。来自解剖学，与任务相关的功能磁共振成像和静息状态研究的集体数据均表明，PMC由三个主要区域组成，分别是前神经突，脾后和后扣带回皮层，每个区域都有独特的功能。我们将对研究结果进行总结，并为以后的研究提供指导。

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