创伤后应激障碍与海马亚区影像学研究

Neuroimaging study of hippocampal subregion involved in post-traumatic stress disorder

海马在恐惧学习和记忆中扮演重要角色,是创伤后应激障碍(post-traumatic stress disorder,PTSD)病生机制的关键脑区。神经影像学研究证实PTSD患者海马结构和功能连接异常,然而海马亚区改变仍不明确。脑结构研究结果表明成人PTSD患者海马角和齿状回萎缩,患者再体验症状可能与齿状回神经发生减少导致的模式分离功能障碍有关。儿童PTSD患者海马角和齿状回变化不显著,海马前下托萎缩最明显,这可能导致恐惧消退和情景记忆缺陷。PTSD患者海马体积改变或具有一定性别特异性偏侧化现象。脑功能研究结果表明PTSD患者海马亚区功能连接选择性损伤,与默认模式网络中关键脑区连通性降低。文章从脑影像学角度系统综述PTSD患者海马亚区结构和功能连接改变,以期促进对PTSD致病机制的理解,识别海马亚区的治疗靶点。

The hippocampus plays an important role in fear learning and memory processing.It is a key brain area in the pathogenesis of post-traumatic stress disorder(PTSD).Neuroimaging studies have confirmed that the hippocampal structure and functional connectivity of patients with PTSD are abnormal,but the changes in hippocampal subregions are still unclear.The results of brain structure studies showed that the cornu ammonis and dentate gyrus atrophy in adult PTSD patients and the symptom of re-experience may be related to pattern separation dysfunction caused by reduced dentate gyrus neurogenesis.Among children diagnosed with PTSD,there is no significant change found in cornu ammonis and dentate gyrus,while atrophy in presubiculum was observed,which could result in fear extinction and deficits in episodic memory.The alteration of hippocampal volume in PTSD may have a gender-specific lateralization phenomenon.The results of brain function studies show that the functional connectivity of hippocampal subregions in PTSD patients is selectively damaged,especially the connectivity with key brain regions in the default mode network is reduced.This article systematically reviews the structural and functional connectivity changes of hippocampal subregions in patients with PTSD from the perspective of neuroimaging,in order to promote the understanding of the pathogenesis of PTSD and identify the therapeutic targets of hippocampal subregions.