Brown Alexa, Villaruel Franz R, Chaudhri Nadia
Center for Studies in Behavioural Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada.
Center for Studies in Behavioural Neurobiology, Department of Psychology, Concordia University, Montreal, QC, Canada.
Behav Brain Res. 2023 Feb 25;440:114248. doi: 10.1016/j.bbr.2022.114248. Epub 2022 Dec 7.
Extinction is a fundamental form of inhibitory learning that is important for adapting to changing environmental contingencies. While numerous studies have investigated the neural correlates of extinction using Pavlovian fear conditioning and appetitive operant reward-seeking procedures, less is known about the neural circuitry mediating the extinction of appetitive Pavlovian responding. Here, we aimed to generate an extensive brain activation map of extinction learning in a rat model of appetitive Pavlovian conditioning. Male Long-Evans rats were trained to associate a conditioned stimulus (CS; 20 s white noise) with the delivery of a 10% sucrose unconditioned stimulus (US; 0.3 ml/CS) to a fluid port. Control groups also received CS presentations, but sucrose was delivered either during the inter-trial interval or in the home-cage. After conditioning, 1 or 6 extinction sessions were conducted in which the CS was presented but sucrose was withheld. We performed Fos immunohistochemistry and network connectivity analyses on a set of cortical, striatal, thalamic, and amygdalar brain regions. Neural activity in the prelimbic cortex, ventral orbitofrontal cortex, nucleus accumbens core, and paraventricular nucleus of the thalamus was greater during recall relative to extinction. Conversely, prolonged extinction following 6 sessions induced increased neural activity in the infralimbic cortex, medial orbitofrontal cortex, and nucleus accumbens shell compared to home-cage controls. All these structures were similarly recruited during recall on the first extinction session. These findings provide novel evidence for the contribution of brain areas and neural networks that are differentially involved in the recall versus extinction of appetitive Pavlovian conditioned responding.
消退是抑制性学习的一种基本形式，对于适应不断变化的环境偶发事件很重要。虽然许多研究使用巴甫洛夫式恐惧条件反射和奖赏性操作性奖赏寻求程序研究了消退的神经相关性，但对于介导奖赏性巴甫洛夫式反应消退的神经回路了解较少。在这里，我们旨在生成一个奖赏性巴甫洛夫式条件反射大鼠模型中消退学习的广泛脑激活图谱。雄性长 Evans 大鼠被训练将条件刺激（CS；20 秒白噪声）与 10%蔗糖非条件刺激（US；0.3 ml/CS）递送至液体端口联系起来。对照组也接受 CS 呈现，但蔗糖要么在试验间隔期间递送，要么在笼内递送。条件反射后，进行 1 或 6 次消退训练，在此期间呈现 CS 但不给予蔗糖。我们对一组皮质、纹状体、丘脑和杏仁核脑区进行了 Fos 免疫组织化学和网络连接性分析。相对于消退，前边缘皮质、腹侧眶额皮质、伏隔核核心和丘脑室旁核在回忆期间的神经活动更强。相反，与笼内对照组相比，6次训练后的长时间消退诱导了边缘下皮质、内侧眶额皮质和伏隔核壳中的神经活动增加。在第一次消退训练的回忆期间，所有这些结构的募集情况相似。这些发现为在奖赏性巴甫洛夫式条件反应的回忆与消退中差异参与的脑区和神经网络的贡献提供了新的证据。
