Neuroscience Graduate Program, University of Vermont, Burlington, VT 05405, United States; Department of Psychological Science, University of Vermont, Burlington, VT 05405, United States.
Department of Psychological Science, University of Vermont, Burlington, VT 05405, United States.
Neurobiol Learn Mem. 2020 May;171:107189. doi: 10.1016/j.nlm.2020.107189. Epub 2020 Feb 14.
The present experiments aimed to expand our understanding of the role of the prelimbic cortex (PL) in the contextual control of instrumental behavior. Research has previously shown that the PL is involved when the "physical context," or chamber in which an instrumental behavior is trained, facilitates performance of the instrumental response (Trask, Shipman, Green, & Bouton, 2017). Recently, evidence has suggested that when a sequence of two instrumental behaviors is required to earn a reinforcing outcome, the first response (rather than the physical chamber) can be the "behavioral context" for the second response (Thrailkill, Trott, Zerr, and Bouton, 2016). Could the PL also be involved in this kind of contextual control? Here rats first learned a heterogenous behavior chain in which the first response (i.e., pressing a lever or pulling a chain) was cued by a discriminative stimulus and led to a second stimulus which cued a second response (i.e., pulling a chain or pressing a lever); the second response led to a sucrose reward. When the first and second responses were tested in isolation in the training context, pharmacological inactivation of the PL resulted in a reduction of the first response, but not the second response. When the second response was performed in the "context" of the first response (i.e., as part of the behavior chain) however, PL inactivation reduced the second response. Overall, these results support the idea that the PL is important for mediating the effects of a training context on instrumental responding, whether the context is physical or behavioral.
本实验旨在加深我们对前额皮质（PL）在工具行为情境控制中作用的理解。先前的研究表明，当“物理情境”（即训练工具行为的腔室）促进工具反应的表现时，PL 会参与其中（Trask、Shipman、Green 和 Bouton，2017）。最近的证据表明，当需要执行两个工具行为序列才能获得强化结果时，第一个反应（而不是物理腔室）可以成为第二个反应的“行为情境”（Thrailkill、Trott、Zerr 和 Bouton，2016）。PL 也可能参与这种情境控制吗？在这里，大鼠首先学习了一种异质行为链，其中第一个反应（即按压杠杆或拉动链条）由辨别刺激提示，并导致第二个刺激提示第二个反应（即拉动链条或按压杠杆）；第二个反应导致蔗糖奖励。当第一个和第二个反应在训练情境中单独测试时，PL 的药理学失活导致第一个反应减少，但第二个反应没有减少。然而，当第二个反应作为第一个反应的“情境”（即行为链的一部分）执行时，PL 失活会减少第二个反应。总体而言，这些结果支持这样一种观点，即 PL 对于调节训练情境对工具反应的影响很重要，无论该情境是物理的还是行为的。
