Dragoi George, Tonegawa Susumu
The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, United States.
Elife. 2013 Dec 10;2:e01326. doi: 10.7554/eLife.01326.
Prior experience accelerates acquisition of novel, related information through processes like assimilation into mental schemas, but the underlying neuronal mechanisms are poorly understood. We investigated the roles that prior experience and hippocampal CA3 N-Methyl-D-aspartate receptor (NMDAR)-dependent synaptic plasticity play in CA1 place cell sequence encoding and learning during novel spatial experiences. We found that specific representations of de novo experiences on linear environments were formed on a framework of pre configured network activity expressed in the preceding sleep and were rapidly, flexibly adjusted via NMDAR-dependent activity. This prior experience accelerated encoding of subsequent experiences on contiguous or isolated novel tracks, significantly decreasing their NMDAR-dependence. Similarly, de novo learning of an alternation task was facilitated by CA3 NMDARs; this experience accelerated subsequent learning of related tasks, independent of CA3 NMDARs, consistent with a schema-based learning. These results reveal the existence of distinct neuronal encoding schemes which could explain why hippocampal dysfunction results in anterograde amnesia while sparing recollection of old, schema-based memories. DOI: http://dx.doi.org/10.7554/eLife.01326.001.
先前的经验通过诸如融入心理图式等过程加速对新颖相关信息的获取，但其潜在的神经元机制却知之甚少。我们研究了先前经验和海马体CA3区N - 甲基 - D - 天冬氨酸受体（NMDAR）依赖性突触可塑性在新的空间体验期间对CA1位置细胞序列编码和学习所起的作用。我们发现，在先前睡眠中表达的预先配置的网络活动框架上形成了对线性环境中全新体验的特定表征，并且通过NMDAR依赖性活动迅速、灵活地进行了调整。这种先前经验加速了对连续或孤立新轨迹上后续体验的编码，显著降低了它们对NMDAR的依赖性。同样，CA3区NMDAR促进了交替任务的全新学习；这种经验加速了后续相关任务的学习，且与CA3区NMDAR无关，这与基于图式的学习一致。这些结果揭示了不同神经元编码模式的存在，这可以解释为什么海马体功能障碍会导致顺行性遗忘，却能保留对基于旧图式的记忆的回忆。DOI: http://dx.doi.org/10.7554/eLife.01326.001 。
