Lesions of the paraventricular nucleus of the thalamus differentially affect sign- and goal-tracking conditioned responses.
Lesions of the paraventricular nucleus of the thalamus differentially affect sign- and goal-tracking conditioned responses.
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DOI：
10.1111/ejn.13031
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发表时间：
2015-10
期刊：
影响因子：
--
通讯作者：
Flagel SB
中科院分区：
文献类型：
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作者：
Haight JL;Fraser KM;Akil H;Flagel SB
最近出现的证据表明丘脑室旁核（PVT）在奖励相关线索的处理中发挥着作用。然而，PVT 在这些过程中的具体作用尚未阐明。在这里，我们使用动物模型来捕获个体对离散奖励相关线索的反应差异，以进一步评估 PVT 在刺激奖励学习中的作用。当老鼠暴露于巴甫洛夫条件反射范式（其中离散线索预测食物奖励）时，会出现两种不同的条件反应。一些被称为信号追踪者的老鼠会接近并操纵提示；另一些则被称为“信号追踪者”。而另一些被称为目标跟踪器的设备则在提示出现后接近奖励交付的位置。对于信号跟踪器和目标跟踪器来说，提示都是预测器。但只有对于信号追踪者来说，这才是一种激励措施。我们使用兴奋性毒性损伤研究了 PVT 在这些条件反应的获得和表达中的作用。结果表明，获取前的 PVT 损伤放大了表型之间的差异——增加了体征跟踪并减弱了目标跟踪行为。在大鼠获得各自的条件反应后，PVT 的损伤也会减弱目标跟踪反应的表达，并增加信号跟踪反应，但在目标跟踪者中是有选择性的。这些结果表明，PVT 的作用是抑制激励显着性对奖励线索的归因，因为该结构内功能活动的破坏增强了符号跟踪的倾向。
Recently evidence has emerged suggesting a role for the paraventricular nucleus of the thalamus (PVT) in the processing of reward-associated cues. However, the specific role of the PVT in these processes has yet to be elucidated. Here we use an animal model that captures individual variation in response to discrete reward-associated cues to further assess the role of the PVT in stimulus-reward learning. When rats are exposed to a Pavlovian conditioning paradigm, wherein a discrete cue predicts food reward, two distinct conditioned responses emerge. Some rats, termed sign-trackers, approach and manipulate the cue; whereas others, termed goal-trackers, approach the location of reward delivery upon cue presentation. For both sign- and goal-trackers the cue is a predictor; but only for sign-trackers is it also an incentive stimulus. We investigated the role of the PVT in the acquisition and expression of these conditioned responses using an excitotoxic lesion. Results indicate that PVT lesions prior to acquisition amplify the differences between phenotypes—increasing sign-tracking and attenuating goal-tracking behavior. Lesions of the PVT after rats had acquired their respective conditioned responses also attenuated the expression of the goal-tracking response, and increased the sign-tracking response, but did so selectively in goal-trackers. These results suggest that the PVT acts to suppress the attribution of incentive salience to reward cues, as disruption of the functional activity within this structure enhances the tendency to sign-track.