Rapid and independent memory formation in the parietal cortex
Rapid and independent memory formation in the parietal cortex
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DOI：
10.1073/pnas.1605719113
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发表时间：
2016-11-15
影响因子：
11.1
通讯作者：
Schoenauer, Monika
中科院分区：
文献类型：
--
作者：
Brodt, Svenja;Poehlchen, Dorothee;Schoenauer, Monika
先前的证据表明，大脑在两个互补的系统中存储记忆，允许快速的可塑性和在不同部位的稳定表征。为了在持久的新皮层存储中建立记忆，在最初编码到海马回路之后，许多学习重复被认为是必要的。为了阐明海马和新皮层对记忆形成早期阶段的动态贡献，我们密切关注人类功能性大脑活动的变化，而志愿者则在两个不同的、最初未知的虚拟环境中导航。在一种情况下，他们能够不断编码关于迷宫空间布局的新信息。在控制条件下，由于布局不断变化，无法学习任何信息。我们的研究结果表明，后顶叶皮层（PPC）对空间位置的记忆进行快速编码，从第一次访问一个位置开始，随着每次额外的遭遇，活动稳步增加。另一方面，在最初的编码过程中，PPC和海马体之间的海马活动和连接是最强的，并且两者都随着额外的遭遇而下降。重要的是，更强的PPC活动与更高的基于记忆的表现有关。与nonlearnable控制条件相比，PPC活性在学习环境中保持升高后，24小时的间隔，表明一个稳定的变化。我们的研究结果反映了快速创建的PPC，这属于最近提出的顶叶记忆网络的记忆表示。顶叶表征的出现是特定于个体经历的，它预测行为，并在离线期间保持稳定，因此必须具有记忆功能。
Previous evidence indicates that the brain stores memory in two complementary systems, allowing both rapid plasticity and stable representations at different sites. For memory to be established in a long-lasting neocortical store, many learning repetitions are considered necessary after initial encoding into hippocampal circuits. To elucidate the dynamics of hippocampal and neocortical contributions to the early phases of memory formation, we closely followed changes in human functional brain activity while volunteers navigated through two different, initially unknown virtual environments. In one condition, they were able to encode new information continuously about the spatial layout of the maze. In the control condition, no information could be learned because the layout changed constantly. Our results show that the posterior parietal cortex (PPC) encodes memories for spatial locations rapidly, beginning already with the first visit to a location and steadily increasing activity with each additional encounter. Hippocampal activity and connectivity between the PPC and hippocampus, on the other hand, are strongest during initial encoding, and both decline with additional encounters. Importantly, stronger PPC activity related to higher memory-based performance. Compared with the nonlearnable control condition, PPC activity in the learned environment remained elevated after a 24-h interval, indicating a stable change. Our findings reflect the rapid creation of a memory representation in the PPC, which belongs to a recently proposed parietal memory network. The emerging parietal representation is specific for individual episodes of experience, predicts behavior, and remains stable over offline periods, and must therefore hold a mnemonic function.