Walker Rachel A, Wright Kristina M, Jhou Thomas C, McDannald Michael A
Psychology Department, Boston College, Chestnut Hill, Massachusetts.
Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina.
Eur J Neurosci. 2020 Feb;51(3):866-880. doi: 10.1111/ejn.14536. Epub 2019 Aug 29.
Aversive, positive prediction error (+PE) provides a mechanism to update and increase future fear to uncertain threat predictors. The ventrolateral periaqueductal grey (vlPAG) has been offered as a neural locus for +PE computation. Yet, a causal demonstration of vlPAG +PE activity to update fear remains elusive. We devised a fear discrimination procedure in which a danger cue predicts shock deterministically and an uncertainty cue predicts shock probabilistically, requiring prediction errors to achieve an appropriate fear response. Recording vlPAG single-unit activity during fear discrimination in Long-Evans rats, we reveal activity related to shock is consistent with +PE and updates subsequent fear to uncertainty at the trial level. We further demonstrate that vlPAG inhibition during shock selectively decreases future fear to uncertainty, but not danger, and temporal emergence of this effect is consistent with single-unit activity. These findings provide causal evidence that vlPAG +PE is necessary for fear updating.
厌恶的正向预测误差（+PE）提供了一种机制，用于更新并增强未来对不确定威胁预测因素的恐惧。腹外侧导水管周围灰质（vlPAG）被认为是+PE计算的神经位点。然而，vlPAG +PE活动对恐惧更新的因果证明仍然难以捉摸。我们设计了一种恐惧辨别程序，其中危险线索确定性地预测电击，不确定线索概率性地预测电击，这需要预测误差来实现适当的恐惧反应。在Long-Evans大鼠进行恐惧辨别期间记录vlPAG单神经元活动，我们发现与电击相关的活动与+PE一致，并在试验水平上更新了随后对不确定性的恐惧。我们进一步证明，电击期间vlPAG抑制选择性地降低了未来对不确定性的恐惧，但不影响对危险的恐惧，并且这种效应的时间出现与单神经元活动一致。这些发现提供了因果证据，表明vlPAG +PE对于恐惧更新是必要的。
