Posttraumatic stress disorder (PTSD) is characterized by intrusions, avoidance, and hyperarousal while patients of the dissociative subtype (PTSD-D) experience additional dissociative symptoms. A neurobiological model proposes hyper-inhibition of limbic structures mediated by prefrontal cortices to underlie dissociation in PTSD. Here, we tested whether functional alterations in fronto-limbic circuits are underpinned by white matter network abnormalities on a network level. 23 women with PTSD-D and 19 women with classic PTSD participated. We employed deterministic diffusion tractography and graph theoretical analyses. Mean fractional anisotropy (FA) was chosen as a network weight and group differences assessed using network-based statistics. No significant white matter network alterations comprising both frontal and limbic structures in PTSD-D relative to classic PTSD were found. A subsequent whole brain exploratory analysis revealed relative FA alterations in PTSD-D in two subcortical networks, comprising connections between the left amygdala, hippocampus, and thalamus as well as links between the left ventral diencephalon, putamen, and pallidum, respectively. Dissociative symptom severity in the PTSD-D group correlated with FA values within both networks. Our findings suggest fronto-limbic inhibition in PTSD-D may present a dynamic neural process, which is not hard-wired via white matter tracts. Our exploratory results point towards altered fiber tract communication in a limbic-thalamic circuit, which may underlie (a) an initial strong emotional reaction to trauma reminders before conscious regulatory processes are enabled and (b) deficits in early sensory processing. In addition, aberrant structural connectivity in low-level motor regions may present neural correlates for dissociation as a passive threat-response.

创伤后应激障碍 (PTSD) 的特点是侵入、回避和过度警觉，而解离亚型 (PTSD-D) 患者则经历额外的解离症状。神经生物学模型提出，前额皮质介导的边缘结构的过度抑制是 PTSD 解离的基础。在这里，我们测试了额边缘回路的功能改变是否是由网络水平上的白质网络异常所支撑的。 23 名患有 PTSD-D 的女性和 19 名患有经典 PTSD 的女性参加了研究。我们采用了确定性扩​​散纤维束成像和图论分析。选择平均分数各向异性（FA）作为网络权重，并使用基于网络的统计数据评估组差异。与经典 PTSD 相比，PTSD-D 中没有发现包括额叶和边缘结构的显着白质网络改变。随后的全脑探索性分析揭示了两个皮质下网络中 PTSD-D 的相对 FA 变化，分别包括左侧杏仁核、海马和丘脑之间的连接，以及左侧腹侧间脑、壳核和苍白球之间的连接。 PTSD-D 组的分离症状严重程度与两个网络中的 FA 值相关。我们的研究结果表明，PTSD-D 中的额叶边缘抑制可能呈现出动态的神经过程，该过程不是通过白质束硬连接的。我们的探索性结果表明边缘-丘脑回路中的纤维束通讯发生了改变，这可能是（a）在有意识的调节过程启用之前对创伤提醒的最初强烈情绪反应和（b）早期感觉处理缺陷的基础。 此外，低级运动区域的异常结构连接可能会呈现出作为被动威胁反应的解离神经相关性。