Kwapis Janine L, Jarome Timothy J, Ferrara Nicole C, Helmstetter Fred J
Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
Neuropsychopharmacology. 2017 Jul;42(8):1688-1697. doi: 10.1038/npp.2017.23. Epub 2017 Jan 31.
Established memories undergo a period of vulnerability following retrieval, a process termed 'reconsolidation.' Recent work has shown that the hypothetical process of reconsolidation is only triggered when new information is presented during retrieval, suggesting that this process may allow existing memories to be modified. Reconsolidation has received increasing attention as a possible therapeutic target for treating disorders that stem from traumatic memories, yet little is known about how this process changes the original memory. In particular, it is unknown whether reconsolidation can reorganize the neural circuit supporting an existing memory after that memory is modified with new information. Here, we show that trace fear memory undergoes a protein synthesis-dependent reconsolidation process following exposure to a single updating trial of delay conditioning. Further, this reconsolidation-dependent updating process appears to reorganize the neural circuit supporting the trace-trained memory, so that it better reflects the circuit supporting delay fear. Specifically, after a trace-to-delay update session, the amygdala is now required for extinction of the updated memory but the retrosplenial cortex is no longer required for retrieval. These results suggest that updating procedures could be used to force a complex, poorly defined memory circuit to rely on a better-defined neural circuit that may be more amenable to behavioral or pharmacological manipulation. This is the first evidence that exposure to new information can fundamentally reorganize the neural circuit supporting an existing memory.
已建立的记忆在提取后会经历一段脆弱期，这一过程被称为“重新巩固”。最近的研究表明，只有在提取过程中呈现新信息时，重新巩固这一假设过程才会被触发，这表明该过程可能使现有记忆得到修改。重新巩固作为治疗源于创伤性记忆的疾病的一个可能的治疗靶点，受到了越来越多的关注，但对于这个过程如何改变原始记忆却知之甚少。特别是，在现有记忆被新信息修改后，重新巩固是否能够重组支持该记忆的神经回路尚不清楚。在此，我们表明，痕迹恐惧记忆在经历单次延迟条件作用更新试验后会经历一个依赖蛋白质合成的重新巩固过程。此外，这种依赖重新巩固的更新过程似乎重组了支持痕迹训练记忆的神经回路，使其能更好地反映支持延迟恐惧的神经回路。具体而言，在进行从痕迹到延迟的更新训练后，杏仁核现在是更新后记忆消退所必需的，但后扣带回皮质在提取时不再是必需的。这些结果表明，更新程序可用于迫使一个复杂、定义不明确的记忆回路依赖于一个定义更明确的神经回路，而这个神经回路可能更易于进行行为或药理学操作。这是首次有证据表明接触新信息能够从根本上重组支持现有记忆的神经回路。
