Atlanta Veterans Affairs Medical Center, Mental Health Service Line, Decatur, Georgia, USA.
Biol Psychiatry. 2011 Mar 15;69(6):556-63. doi: 10.1016/j.biopsych.2010.09.013. Epub 2010 Oct 29.
The symptoms of posttraumatic stress disorder (PTSD) can be explained, at least in part, as an inability to inhibit learned fear during conditions of safety. Our group has shown that fear inhibition is impaired in both combat and civilian PTSD populations. On the basis of our earlier findings, we employed an established fear extinction paradigm to further explore fear dysregulation in a civilian traumatized population.
Fear-potentiated startle (FPS) was examined in 127 trauma-exposed individuals with and without PTSD. We used a protocol in which conditioned fear was first acquired through the presentation of one colored shape (reinforced conditioned stimulus, [CS+]) that was paired with an aversive air blast to the larynx (unconditioned stimulus) and a different colored shape that was not paired to the air blast (nonreinforced condition stimulus). Fear was extinguished 10 min later through repeated presentations of the CSs without reinforcement.
Both groups demonstrated successful fear conditioning on the basis of startle and unconditioned stimulus-expectancy ratings; however, participants with PTSD displayed greater FPS responses to the CS+ and nonreinforced conditioned stimulus compared with the group without PTSD. During fear extinction, the PTSD group showed elevated FPS responses to the previously reinforced CS+ during the early and middle stages of extinction. During the acquisition and extinction phases, PTSD participants with higher levels of reexperiencing symptoms exhibited greater potentiated startle responses to the CS+ compared with PTSD participants with lower reexperiencing symptoms.
These results suggest that PTSD is associated with enhanced fear learning and a greater "fear load" to extinguish after conditioned fear is acquired.
创伤后应激障碍（PTSD）的症状至少可以部分解释为在安全条件下无法抑制习得性恐惧。我们的研究小组已经表明，战斗和非战斗 PTSD 人群都存在恐惧抑制受损的现象。基于我们早期的发现，我们采用了已建立的恐惧消退范式来进一步探索平民创伤人群的恐惧失调。
在 127 名有或没有 PTSD 的创伤后个体中检查了恐惧增强的惊吓（FPS）。我们使用了一种方案，首先通过呈现一个有色形状（强化条件刺激，[CS+]）来获得条件性恐惧，该形状与喉部的厌恶性空气冲击（非条件刺激）配对，以及一个不同的颜色形状不与空气冲击配对（非强化条件刺激）。10 分钟后，通过重复呈现无强化的 CS 来消除恐惧。
两组在惊吓和非条件刺激预期评分的基础上均表现出成功的恐惧条件反射；然而，与无 PTSD 组相比，PTSD 组对 CS+和非强化条件刺激的 FPS 反应更大。在恐惧消退期间，PTSD 组在消退的早期和中期对先前强化的 CS+表现出更高的 FPS 反应。在获得和消退阶段，经历再体验症状水平较高的 PTSD 参与者对 CS+的增强惊吓反应大于经历再体验症状水平较低的 PTSD 参与者。
这些结果表明，PTSD 与增强的恐惧学习以及在获得条件性恐惧后需要消除更大的“恐惧负荷”有关。
