急性应激对执行功能的影响：ERP研究

Stress can lead to an increased activity of the hypothalamic-pituitary-adrenocortical axis (HPA axis). HPA axis releases the glucocorticoids, which can return to the central nervous system to influence the structure and function of the target brain regions, such as the prefrontal cortex and so on. Hence, stress has impacts on cognition and emotion. The executive function, which is associated with the prefrontal cortex, is higher-order cognition function, and it has an important significance to an individual’s adaptation and survival, especially in situations of environmental change and acute stress. Previous studies which examined the effects of acute stress on executive function mainly focused on the behavioral level. A few studies also used fMRI technique. However, fMRI has a limited temporal resolution and may not elucidate how acute stress affects different stages of cognitive processing. The event-related potentials technique, known as its high temporal resolution in milliseconds, is an ideal method to more precisely examine alterations in the dynamic time course of neural activity under acute stress exposure. Therefore, the purpose of the current study was to investigate how acute stress effects on executive functions by using the event-related potentials technique. The questionnaires and salivary cortisol were collected to assess the level of acute stress. We focused on four executive functions, including working memory, response inhibition, error processing and emotion regulation. This study not only facilitates the understanding of the effects of acute stress on executive functions, but also provides scientific indicators and theoretical basis for stress assessment and intervention.

外环境的应激源通过激活HPA轴释放肾上腺皮质激素，后者又返回到中枢神经系统，影响前额叶等脑区的结构和功能，进而影响认知和情绪。前额叶是执行功能的重要中枢，执行功能又是大脑的高级认知活动，对于个体的适应和生存有着重要的意义，尤其是在面临环境突变和急性应激的状态下。以往研究主要从行为层面探索急性应激对执行功能的影响，缺乏深入的认知神经机制的探讨。虽有少量采用fMRI的研究，但由于其较低的时间分辨率，导致我们无法了解急性应激对执行功能影响的动态时间进程。事件相关电位具有毫秒级的时间分辨率，为我们提供了更好的技术手段以了解急性应激对执行功能影响的神经机制。因此本项目以问卷和唾液皮质醇作为评定急性应激的主客观指标，采用事件相关电位技术，考察急性应激对工作记忆、反应抑制、错误加工和情绪调节四种执行功能的影响。通过了解个体在面对急性应激时的心理响应特征及其脑机制，为应激评估和干预提供科学指标和理论基础。

外环境的应激源通过激活HPA轴释放肾上腺皮质激素，后者又返回到中枢神经系统，影响前额叶等脑区的结构和功能，进而影响认知和情绪。前额叶是执行功能的重要中枢，执行功能又是大脑的高级认知活动，对于个体的适应和生存有着重要的意义，尤其是在面临环境突变和急性应激的状态下。本项目采用具有毫秒级的时间分辨率的事件相关电位技术，考察了急性应激对多个执行功能的影响。（1）考察皮质醇觉醒反应（CAR）与同一天的反应抑制功能之间的关系，即CAR是否能预测反应抑制功能（包括行为绩效和脑电指标）。结果发现在正常人群中，CAR越大，反应抑制的N2波幅越大，而对于CAR积极反应组来说，CAR与NoGo试次的误报率呈负相关。这说明CAR不仅可以预测同一天的反应抑制功能的早期认知阶段（如冲突监控阶段），还可以预测行为反应绩效。（2）考察工作记忆的行为绩效和脑电指标是否以及如何预测HPA轴对急性应激的响应能力。结果发现延长的反应时和减少的P2波幅能够预测HPA轴对急性应激的响应能力减弱。本研究支持了工作记忆可以作为潜在的HPA轴对急性应激响应的认知神经标记物。（3）考察新入伍应激对执行功能的影响，发现入伍新兵战士的应激水平与执行功能中的反应抑制能力和任务转换能力存在负相关，新兵应激水平越强，反应抑制能力和任务转换能力越差，体现在反应抑制的虚报率升高和任务转换能力的正确率下降。这些发现能更好地认识新兵战士的心理状况，为未来的新兵评测、训练绩效等工作提供科研依据。