Neuropsychopharmacology Lab, Section Pharmacology, Department Diagnostic & Public Health, P.le Scuro 10, University of Verona, Verona, Italy.
Department of Health Sciences, University of Florence, Florence, Italy.
Brain Res. 2019 Jul 1;1714:193-201. doi: 10.1016/j.brainres.2019.03.006. Epub 2019 Mar 7.
Memory reconsolidation enables the update of a previously consolidated memory trace after its reactivation. Although Pavlovian memory reconsolidation has been widely demonstrated, instrumental memory reconsolidation is still debated. The most critical issue on instrumental memory reconsolidation findings have mainly been linked to the presence of specific boundary conditions for reactivation, for instance contextual parameters. In this study, we investigated the role of the spatial context on molecular markers of sucrose instrumental memory reactivation. Following withdrawal, rats previously conditioned to sucrose self-administration underwent either instrumental memory retrieval or no-retrieval in the conditioned context (Context A, AA condition) or in a modified version of the conditioned context (Context B, AB condition). Two hours later, the level of GluA1 and GluN2B receptors, Zif268 and phosphorylated-rpS6 (rpS6P) was measured in key brain areas for memory reactivation. Retrieval in Context A significantly increased GluA1Rs and GluN2BRs in amygdala compared to no-retrieval, indicating that memory successfully reactivated and destabilized. Moreover, Zif268 level was significantly increased after retrieval in Context A in the nucleus accumbens shell, central and basolateral amygdala but not in the hippocampus, while retrieval in Context B significantly increased Zif268 level in all brain areas. On the other hand, rpS6P level was increased in the nucleus accumbens shell and central amygdala, but decreased in the hippocampus, after retrieval in Context A, while retrieval in Context B did not change rpS6P level in brain areas, except for a small but significant decrease in hippocampus. While the increase of Zif268 level indicated that memory reactivation has been triggered in both the conditions, the lack of change in rpS6P levels after retrieval in Context B - in particular in the central amygdala - suggests that the reconsolidation process could not occur after memory reactivation in a context different from the conditioned one.
记忆再巩固使先前巩固的记忆痕迹在其重新激活后得以更新。尽管已经广泛证明了经典条件反射记忆的再巩固，但工具性记忆的再巩固仍然存在争议。工具性记忆再巩固发现的最关键问题主要与再激活的特定边界条件有关，例如上下文参数。在这项研究中，我们研究了空间上下文对蔗糖工具性记忆再激活的分子标记的作用。在撤出后，先前接受过蔗糖自我给药条件作用的大鼠在条件性环境（环境 A，AA 条件）或条件性环境的修改版本（环境 B，AB 条件）中进行了工具性记忆检索或未检索。两小时后，在记忆再激活的关键脑区测量了 GluA1 和 GluN2BR 受体、Zif268 和磷酸化-rpS6（rpS6P）的水平。与未检索相比，环境 A 中的检索显著增加了杏仁核中的 GluA1Rs 和 GluN2BRs，表明记忆成功重新激活并失稳。此外，在环境 A 中检索后，伏隔核壳、中央和基底杏仁核中的 Zif268 水平显著增加，但海马体中没有增加，而在环境 B 中检索后，所有脑区的 Zif268 水平均显著增加。另一方面，在环境 A 中检索后，海马体、中央杏仁核中的 rpS6P 水平增加，但在海马体中减少，而在环境 B 中检索后，除了海马体中的一小部分但显著减少外，脑区中的 rpS6P 水平没有变化。虽然 Zif268 水平的增加表明两种情况下都触发了记忆再激活，但在环境 B 中检索后 rpS6P 水平没有变化 - 特别是在中央杏仁核中 - 表明在与条件性环境不同的环境中记忆再激活后，再巩固过程可能不会发生。
