The midbrain periaqueductal gray (PAG) coordinates the expression and topography of defensive behaviors to threat and also plays an important role in Pavlovian fear learning itself. Whereas the role of PAG in the expression of defensive behavior is well understood, the relationship between the activity of PAG neurons and fear learning, the exact timing of PAG contributions to learning during the conditioning trial, and the contributions of different PAG columns to fear learning are poorly understood. We assessed the effects of optogenetic inhibition of lateral (LPAG) and ventrolateral PAG (VLPAG) neurons on fear learning. Using adenoassociated viral vectors expressing halorhodopsin, we show that brief optogenetic inhibition of LPAG or VLPAG during delivery of the shock unconditioned stimulus (US) augments acquisition of contextual or cued fear conditioning, and we also show that this inhibition augments postencounter defensive responses to a nonnoxious threat. Taken together, these results show that LPAG and VLPAG serve a key role in the regulation of Pavlovian fear learning at the time of US delivery. These findings provide strong support for existing models that state that LPAG and VLPAG contribute to a fear prediction error signal determining variations in the effectiveness of the aversive US in supporting learning. (PsycINFO Database Record

中文翻译：

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短暂的光遗传学抑制大鼠外侧或腹侧导水管周围灰色增强了对Pavlovian恐惧条件的获取。

中脑导水管周围灰色（PAG）协调了防御行为对威胁的表达和地形，并且在巴甫洛夫式恐惧学习本身中也发挥着重要作用。众所周知，PAG在防御行为表达中的作用是：PAG神经元活动与恐惧学习之间的关系；在适应性试验中，PAG对学习的确切时机；以及不同PAG列对恐惧学习的贡献之间的关系。知之甚少。我们评估了对恐惧学习的外侧（LPAG）和腹侧PAG（VLPAG）神经元的光遗传学抑制作用。使用表达卤代视紫红质的腺相关病毒载体，我们表明，在无条件刺激（美国）的传递过程中，对LPAG或VLPAG的短暂光遗传学抑制作用增强了情境或暗示的恐惧条件的获取，并且我们还表明，这种抑制作用增强了对非有害威胁的en后防御反应。总之，这些结果表明，在美国交付时，LPAG和VLPAG在调节巴甫洛夫式恐惧学习中起着关键作用。这些发现为现有模型提供了有力的支持，现有模型表明LPAG和VLPAG有助于确定恐惧心理预测错误信号，从而确定厌恶性美国在支持学习方面的有效性差异。（PsycINFO数据库记录 这些结果表明，在美国交付时，LPAG和VLPAG在调节巴甫洛夫式恐惧学习中起着关键作用。这些发现为现有模型提供了有力的支持，现有模型表明LPAG和VLPAG有助于确定恐惧心理预测错误信号，从而确定厌恶性美国在支持学习方面的有效性差异。（PsycINFO数据库记录 这些结果表明，在美国交付时，LPAG和VLPAG在调节巴甫洛夫式恐惧学习中起着关键作用。这些发现为现有模型提供了有力的支持，现有模型表明LPAG和VLPAG有助于确定恐惧心理预测错误信号，从而确定厌恶性美国在支持学习方面的有效性差异。（PsycINFO数据库记录