Thome Janine, Densmore Maria, Terpou Braeden A, Théberge Jean, McKinnon Margaret C, Lanius Ruth A
Department of Psychiatry, Western University, London, ON, Canada.
Department of Theoretical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
Front Behav Neurosci. 2022 May 30;16:862192. doi: 10.3389/fnbeh.2022.862192. eCollection 2022.
Increasing evidence points toward the need to extend the neurobiological conceptualization of posttraumatic stress disorder (PTSD) to include evolutionarily conserved neurocircuitries centered on the brainstem and the midbrain. The reticular activating system (RAS) helps to shape the arousal state of the brain, acting as a bridge between brain and body. To modulate arousal, the RAS is closely tied to the autonomic nervous system (ANS). Individuals with PTSD often reveal altered arousal patterns, ranging from hyper- to blunted arousal states, as well as altered functional connectivity profiles of key arousal-related brain structures that receive direct projections from the RAS. Accordingly, the present study aims to explore resting state functional connectivity of the RAS and its interaction with the ANS in participants with PTSD and its dissociative subtype.
Individuals with PTSD ( = 57), its dissociative subtype (PTSD + DS, = 32) and healthy controls ( = 40) underwent a 6-min resting functional magnetic resonance imaging and pulse data recording. Resting state functional connectivity (rsFC) of a central node of the RAS - the pedunculopontine nuclei (PPN) - was investigated along with its relation to ANS functioning as indexed by heart rate variability (HRV). HRV is a prominent marker indexing the flexibility of an organism to react adaptively to environmental needs, with higher HRV representing greater effective adaptation.
Both PTSD and PTSD + DS demonstrated reduced HRV as compared to controls. HRV measures were then correlated with rsFC of the PPN. Critically, participants with PTSD and participants with PTSD + DS displayed inverse correlations between HRV and rsFC between the PPN and key limbic structures, including the amygdala. Whereas participants with PTSD displayed a relationship between HRV and PPN rsFC with the amygdala, participants with PTSD + DS demonstrated a relationship between HRV and PPN rsFC with the amygdala.
The present exploratory investigation reveals contrasting patterns of arousal-related circuitry among participants with PTSD and PTSD + DS, providing a neurobiological lens to interpret hyper- and more blunted arousal states in PTSD and PTSD + DS, respectively.
越来越多的证据表明，有必要扩展创伤后应激障碍（PTSD）的神经生物学概念，以纳入以脑干和中脑为中心的进化保守神经回路。网状激活系统（RAS）有助于塑造大脑的唤醒状态，充当大脑与身体之间的桥梁。为了调节唤醒，RAS与自主神经系统（ANS）密切相关。PTSD患者通常表现出改变的唤醒模式，从过度唤醒到唤醒迟钝，以及接受RAS直接投射的关键唤醒相关脑结构的功能连接谱改变。因此，本研究旨在探讨PTSD患者及其解离亚型患者静息状态下RAS的功能连接及其与ANS的相互作用。
PTSD患者（n = 57）、其解离亚型（PTSD + DS，n = 32）和健康对照者（n = 40）接受了6分钟的静息功能磁共振成像和脉搏数据记录。研究了RAS的一个中心节点——脚桥核（PPN）的静息状态功能连接（rsFC），以及其与以心率变异性（HRV）为指标的ANS功能的关系。HRV是一个突出的指标，用于衡量生物体对环境需求做出适应性反应的灵活性，较高的HRV表示更强的有效适应性。
与对照组相比，PTSD组和PTSD + DS组的HRV均降低。然后将HRV测量值与PPN的rsFC进行相关性分析。至关重要的是，PTSD患者和PTSD + DS患者在HRV与PPN和包括杏仁核在内的关键边缘结构之间的rsFC之间呈现负相关。PTSD患者在HRV与PPN和杏仁核的rsFC之间呈现一种关系，而PTSD + DS患者在HRV与PPN和杏仁核的rsFC之间呈现另一种关系。
本探索性研究揭示了PTSD患者和PTSD + DS患者之间与唤醒相关的神经回路的不同模式，为分别解释PTSD和PTSD + DS中的过度唤醒和更迟钝唤醒状态提供了一个神经生物学视角。
