Assareh Neda, Bagley Elena E, Carrive Pascal, McNally Gavan P
School of Psychology, University of New South Wales Sydney.
University of Sydney.
Behav Neurosci. 2017 Dec;131(6):454-459. doi: 10.1037/bne0000217. Epub 2017 Oct 30.
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
中脑导水管周围灰质（PAG）协调对威胁的防御行为的表达和拓扑结构，并且在巴甫洛夫恐惧学习本身中也起着重要作用。虽然PAG在防御行为表达中的作用已得到充分理解，但PAG神经元活动与恐惧学习之间的关系、PAG在条件反射试验期间对学习贡献的确切时间，以及不同PAG柱对恐惧学习的贡献却知之甚少。我们评估了对外侧（LPAG）和腹外侧PAG（VLPAG）神经元进行光遗传学抑制对恐惧学习的影响。使用表达嗜盐菌视紫红质的腺相关病毒载体，我们发现，在给予电击非条件刺激（US）期间对LPAG或VLPAG进行短暂的光遗传学抑制会增强情境性或线索性恐惧条件反射的习得，并且我们还发现这种抑制会增强遭遇后对无害威胁的防御反应。综上所述，这些结果表明，LPAG和VLPAG在给予US时对巴甫洛夫恐惧学习的调节中起关键作用。这些发现为现有模型提供了有力支持，这些模型认为LPAG和VLPAG有助于产生恐惧预测误差信号，该信号决定了厌恶性US在支持学习方面的有效性差异。（PsycINFO数据库记录）
