Miller Lauren A, Heroux Nicholas A, Stanton Mark E
University of Delaware, United States.
University of Delaware, United States.
Behav Brain Res. 2019 Jan 1;356:236-242. doi: 10.1016/j.bbr.2018.08.012. Epub 2018 Aug 22.
In standard contextual fear conditioning (sCFC), learning of the context and formation of the context-shock association occur in the same training session whereas in the context preexposure facilitation effect (CPFE) learning the context (preexposure) and the context-shock association (training) are separated by 24 h. In both procedures conditioned freezing can be measured immediately (post-shock test) or during a 24-hour retention test. In adult rats, disrupting basolateral amygdala (BLA) activity or plasticity during training on sCFC impairs both post-shock and retention freezing [Maren et al, 1996; 1]. This manipulation on the training day of the CPFE disrupts retention freezing but effects on post-shock freezing are unknown [Matus-Amat et al, 2007; 2]. Experiment 1 extended this literature from adult to adolescent rats and to the role of BLA activity and plasticity in post-shock freezing during the CPFE. Intra-BLA infusions of muscimol prior to the training day of the CPFE disrupted both post-shock and retention freezing in Postnatal Day (PD) 31-33 rats. In the second two experiments, intra-BLA infusions of APV prior to the training day of sCFC disrupted retention but not post-shock freezing, while infusions of APV prior to training of the CPFE disrupt both post-shock and retention freezing. Our findings suggest that the BLA plasticity plays a different role in the CPFE vs. sCFC. Its role in the CPFE is similar in both adolescent and adult rats, while the role of the BLA in post-shock freezing during sCFC may differ across age or across studies that employ different procedures or parameters.
在标准情境恐惧条件反射（sCFC）中，对情境的学习以及情境 - 电击关联的形成发生在同一训练阶段，而在情境预暴露促进效应（CPFE）中，对情境的学习（预暴露）和情境 - 电击关联的形成（训练）被间隔24小时。在这两种程序中，条件性僵立反应都可以在电击后立即测量（电击后测试），或者在24小时的记忆测试期间测量。在成年大鼠中，在sCFC训练期间破坏基底外侧杏仁核（BLA）的活动或可塑性会损害电击后和记忆测试中的僵立反应[Maren等人，1996年；1]。在CPFE训练日进行这种操作会破坏记忆测试中的僵立反应，但对电击后僵立反应的影响尚不清楚[Matus - Amat等人，2007年；2]。实验1将这一研究从成年大鼠扩展到了青春期大鼠，并研究了BLA活动和可塑性在CPFE期间电击后僵立反应中的作用。在CPFE训练日前向BLA内注射蝇蕈醇会破坏出生后第31 - 33天大鼠的电击后和记忆测试中的僵立反应。在接下来的两个实验中，在sCFC训练日前向BLA内注射APV会破坏记忆测试中的僵立反应，但不影响电击后僵立反应，而在CPFE训练前注射APV则会破坏电击后和记忆测试中的僵立反应。我们的研究结果表明，BLA可塑性在CPFE和sCFC中发挥着不同的作用。它在CPFE中的作用在青春期和成年大鼠中相似，而BLA在sCFC期间电击后僵立反应中的作用可能因年龄不同，或者因采用不同程序或参数而有所不同。
