Departments of Psychiatry and Anatomy & Neurobiology, School of Medicine, University of Puerto Rico, P.O. Box 365067, San Juan, 00936-5067, Puerto Rico.
Neuroscience Division, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11724, USA.
Psychopharmacology (Berl). 2019 Jan;236(1):399-406. doi: 10.1007/s00213-018-5012-7. Epub 2018 Sep 27.
Neurons in PL and IL project densely to two areas implicated in active avoidance: the basolateral amygdala (BLA) and the ventral striatum (VS). We therefore combined c-Fos immunohistochemistry with retrograde tracers to characterize signaling in platform-mediated active avoidance.
Male rats were infused with retrograde tracers (CTB, FB) into basolateral amygdala and ventral striatum and conditioned to avoid tone-signaled footshocks by stepping onto a nearby platform. In a subsequent test session, rats received either 2 unreinforced tones (avoidance retrieval) or 15 unreinforced tones (avoidance extinction) followed by analysis of c-Fos combined with fluorescent imaging of retrograde tracers.
Retrieval of avoidance did not activate IL neurons, but did activate PL neurons projecting to BLA, and to a lesser extent VS. Extinction of avoidance activated IL neurons projecting to both BLA and VS, as well as PL neurons projecting to VS.
Our observation that avoidance retrieval is signaled by PL projections to BLA suggests that PL may modulate VS indirectly via BLA, and agrees with other findings implicating BLA in active avoidance. Less expected was the signaling of extinction via PL inputs to VS, which may converge with IL inputs to VS to inhibit expression of avoidance.
PL 和 IL 中的神经元密集投射到两个与主动回避有关的区域：基底外侧杏仁核（BLA）和腹侧纹状体（VS）。因此，我们结合 c-Fos 免疫组织化学和逆行示踪剂来描述平台介导的主动回避中的信号传递。
雄性大鼠被逆行示踪剂（CTB、FB）注入基底外侧杏仁核和腹侧纹状体，并通过踏上前附近的平台来适应回避与声音信号相关的足部电击。在随后的测试会话中，大鼠接受了 2 个未强化的音调（回避检索）或 15 个未强化的音调（回避消退），然后对 c-Fos 进行分析，并结合逆行示踪剂的荧光成像。
回避的检索并没有激活 IL 神经元，但激活了投射到 BLA 的 PL 神经元，以及程度较轻的 VS。回避的消退激活了投射到 BLA 和 VS 的 IL 神经元，以及投射到 VS 的 PL 神经元。
我们观察到回避检索是由 PL 投射到 BLA 的信号传递的，这表明 PL 可能通过 BLA 间接调节 VS，这与其他发现一致，即 BLA 参与主动回避。更出乎意料的是，通过 PL 输入到 VS 的消退信号传递，这可能与 IL 输入到 VS 汇聚，以抑制回避的表达。
