Self-related processes define assorted self-relevant or social-cognitive functions that allow us to gather insight and to draw inferences related to our own mental conditions. Self-related processes are mediated by the default mode network (DMN), which, critically, shows altered functionality in individuals with posttraumatic stress disorder (PTSD). In PTSD, the midbrain periaqueductal gray (PAG) demonstrates stronger functional connectivity with the DMN [i.e., precuneus (PCN), medial prefrontal cortex (mPFC)] as compared to healthy individuals during subliminal, trauma-related stimulus processing. Here, we analyzed the directed functional connectivity between the PAG and the PCN, as well as between the PAG and the mPFC to more explicitly characterize the functional connectivity we have observed previously on the corresponding sample and paradigm. We evaluated three models varying with regard to context-dependent modulatory directions (i.e., bi-directional, bottom-up, top-down) among individuals with PTSD (n = 26) and healthy participants (n = 20), where Bayesian model selection was used to identify the most optimal model for each group. We then compared the effective connectivity strength for each parameter across the models and between our groups using Bayesian model averaging. Bi-directional models were found to be favoured across both groups. In PTSD, we revealed the PAG to show stronger excitatory effective connectivity to the PCN, as well as to the mPFC as compared to controls. In PTSD, we further demonstrated that PAG-mediated effective connectivity to the PCN, as well as to the mPFC were modulated more strongly during subliminal, trauma-related stimulus conditions as compared to controls. Clinical disturbances towards self-related processes are reported widely by participants with PTSD during trauma-related stimulus processing, where altered functional connectivity directed by the PAG to the DMN may elucidate experiential links between self- and trauma-related processing in traumatized individuals.

自我相关的过程定义了各种自我相关的或社会认知的功能，这些功能使我们能够收集见识并得出与我们自己的心理状况有关的推论。自我相关的过程由默认模式网络（DMN）介导，该网络严重显示出创伤后应激障碍（PTSD）患者的功能发生了改变。在PTSD中，与下肢，创伤相关的刺激过程中的健康个体相比，中脑导水管周围灰色（PAG）表现出与DMN [即前神经（PCN），内侧前额叶皮层（mPFC）]的更强功能连接。在这里，我们分析了PAG与PCN之间以及PAG与mPFC之间的定向功能连接，以更明确地表征我们之前在相应的样本和范式上观察到的功能连接。我们评估了三种模型，这些模型在PTSD（n = 26）和健康参与者（n = 20）的个体之间，取决于上下文相关的调制方向（即双向，自下而上，自上而下），其中贝叶斯模型选择用于确定每个组的最佳模型。然后，我们使用贝叶斯模型平均比较了模型之间以及各组之间每个参数的有效连接强度。双向模型在两组中均受青睐。在PTSD中，我们发现PAG与PCN以及与mPFC相比，显示出更强的兴奋性有效连接性。在PTSD中，我们进一步证明了在下意识期，PAG介导的与PCN以及mPFC的有效连接受到了更强烈的调节，与对照组相比，与创伤有关的刺激条件。在创伤相关刺激过程中，PTSD参与者广泛报道了对自我相关过程的临床障碍，其中PAG指向DMN的功能连接性的改变可能阐明了受创伤个体中自我和创伤相关过程之间的经验联系。