关于恐惧增强惊吓反射效应的神经环路研究

The startle reflex is a defensive response to sudden or threatening stimuli. The previous studies show that startle reflex is increased in the presence of a fear stimulus, called “fear-potentiated startle”. However, the detailed mechanism, especially the neuronal pathway of fear-potentiated startle, is still not clear. In complex vertebrates, including humans, the amygdala perform primary roles in the formation and storage of memories associated with emotional events, including fear and its related negative emotions. The brain lesions studies show that the nucleus reticularis pontis caudalis plays critical roles in the acoustic startle pathway. So does there exist any direct or indirect neuronal pathway between the amygdala and the nucleus reticularis pontis caudalis? If so, can these connections underlie the mechanism of fear-potentiated startle? This project is to identify the neuronal pathway of fear and its related negative emotions potentiated startle reflex, by systematically applying a variety of advanced experimental techniques at the molecular and cellular level and up to animal behavior, including molecular biology, electrophysiology, the anterograde and retrograde pathway tracing techniques based on virus, optogentics, human and animal functional magnetic resonance imaging (fMRI) and multichannel neuronal recording in vivo. Based on the neuronal pathway of fear-potentiated startle, we will additionally try to discover the pathological mechanism of the startle-related diseases and to develop more powerful treatment and medicine.

惊吓反射是突发性的强感觉刺激诱发的一种防御性反射。研究表明，恐惧及其相关负性情绪能显著的增强惊吓反射，该效应是一个非常明确的与恐惧相关的行为现象，从低级到高级动物普遍存在，但是其生理机制尚不清楚。众多研究表明恐惧形成和表达的关键中枢在杏仁核，而惊吓反射的中枢核团为脑干部位的脑桥尾侧网状核。那么，杏仁核与脑桥尾侧网状核之间是否存在直接或间接的神经环路联系，而这种联系是否是恐惧增强惊吓反射效应的生理机制呢？本项目的研究将通过神经环路示踪技术、光遗传学技术、高场功能磁共振成像、多通道胞外神经信号电生理记录等多种研究手段，深入研究恐惧及其相关负性情绪增强惊吓反射这一行为的神经环路基础，揭示杏仁核向脑桥尾侧网状核投射的神经通路的结构特点、功能及调控的作用和机制，并以该环路为引导，研发具有自主知识产权的相关神经疾病的治疗方法和药物。

惊吓反射是动物应对突发性危险刺激的一种本能反射。尽管许多研究均表明，恐惧及其相关负性情绪能显著增强惊吓反射（FPS），但其中的生理机制尚不清楚。传统观点认为惊吓反射的中枢核团为脑干部位的脑桥尾侧网状核(PnC)。本课题组通过结合病毒示踪、在体光遗传及电生理记录等手段发现一条强声刺激诱发惊吓反射以及恐惧如何增强该反射的新环路。声音信息从耳蜗核(CRN)经中脑三叉神经束(MsC)传递到脑桥腹侧被盖区(RgN)，最终引起脊髓运动神经元的激活。在恐惧条件下，中缝背核(DR)释放的五羟色胺通过作用于RgN处GABA能中间神经元上的5-HT1b型受体参与介导抑制性微环路，从而增强惊吓反射。本课题组的工作阐明了FPS的环路机制，对寻找预防和治疗与恐惧和惊吓相关的神经疾病的方法也有着重要的意义。工作结果正在整理投稿中。.为了研究DR核团单个神经元内递质含量响应条件性恐惧刺激的变化，本课题组结合电生理膜片钳和质谱分析建立了快速高灵敏的单细胞组分分析技术，并用该技术在单个神经元内鉴定出50多种物质，相关工作于2017年发表在《美国国家科学院院报》（PNAS）。单细胞质谱技术的应用也为后续单个神经元组分分析、神经元分类以及病理状态下单个神经元中组分变化分析提供强有力的手段。