Dissociative responses to conscious and non-conscious fear impact underlying brain function in post-traumatic stress disorder
Dissociative responses to conscious and non-conscious fear impact underlying brain function in post-traumatic stress disorder
复制标题
DOI：
10.1017/s0033291708002742
复制
发表时间：
2008-12-01
影响因子：
6.9
通讯作者：
Bryant, R.
中科院分区：
文献类型：
--
作者：
Felmingham, K.;Kemp, A. H.;Bryant, R.
背景创伤后应激障碍（PTSD）中的分离反应被认为是限制唤醒的策略反应。神经影像学研究表明，在PTSD中，个体对威胁表现出分离和过度唤醒反应，这两种反应是不同的。前额叶活动的增加可能反映了分离中边缘系统唤醒网络的调节增强。如果解离是对威胁的一种高阶调节反应，那么对威胁刺激的有意识和自动加工可能存在不同的反应。本研究通过考察不同意识水平下分离对恐惧加工的影响来解决这一问题。使用1.5 T扫描仪的功能性磁共振成像（fMRI）检查23名PTSD患者在有意识和无意识（使用后向掩蔽）条件下对恐惧（与中性）面部表情的激活。比较了11名显示非分离反应的个体和12名显示分离反应的个体对有意识和无意识感知的恐惧刺激的激活。与非分离性PTSD相比，分离性PTSD与腹侧前额叶皮层的有意识恐惧激活增强有关，与双侧杏仁核、杏仁核和左丘脑的无意识恐惧激活增强有关。在分离组中，背内侧前额叶区的激活相对减少，这是明显的。这些发现证实了我们的假设，即在分离性PTSD中，前额叶活动增强，意识恐惧增强，边缘系统网络活动增强，无意识恐惧增强。这支持了这样一种理论，即分离是一种调节策略，用于科普PTSD中的极端唤醒，但这种策略似乎只在有意识的威胁处理过程中起作用。
Background. Dissociative reactions in post-traumatic stress disorder (PTSD) have been regarded as strategic responses that limit arousal. Neuroimaging studies suggest distinct prefrontal responses in individuals displaying dissociative and hyperarousal responses to threat in PTSD. Increased prefrontal activity may), reflect enhanced regulation of limbic arousal networks in dissociation. If dissociation is a higher-order regulatory response to threat, there may he differential responses to conscious and automatic processing of threat stimuli. This study addresses this question by examining the impact of dissociation on fear processing at different levels of awareness.Method. Functional magnetic resonance imaging (fMRI) with a 1.5-T scanner was used to examine activation to fearful (versus neutral) facial expressions during consciously attended and non-conscious (using backward masking) conditions in 23 individuals with PTSD. Activation in 11 individuals displaying non-dissociative reactions was compared to activation in 12 displaying dissociative reactions to consciously and non-consciously perceived fear stimuli.Results. Dissociative PTSD was associated with enhanced activation in the ventral prefrontal cortex for conscious fear, and in the bilateral amygdala, insula and left thalamus for non-conscious fear compared to non-dissociative PTSD. Comparatively reduced activation in the dissociative group was apparent in dorsomedial prefrontal regions for conscious fear faces.Conclusions. These findings confirm our hypotheses of enhanced prefrontal activity to conscious fear and enhanced activity in limbic networks to non-conscious fear in dissociative PTSD. This supports the theory that dissociation is a regulatory strategy invoked to cope with extreme arousal in PTSD, but this strategy appears to function only during conscious processing of threat.