健康与遗传心理学研究室知识库

伴随着早晨醒来，人类的皮质醇水平会短暂地升高，这种现象被称为皮质醇觉醒反应(Cortisol awakening response, CAR )。 CAR在个体内具有较大的稳定性，常被用作神经内分泌活动的特质。每天的CAR也会发生波动，即具有状态性。作为下丘脑一垂体一肾上腺皮质(Hypothalamic-pituitary-adrenal cortex, HPA)轴活动的终端产物，皮质醇和认知功能的关系，一直以来是“应激”领域的关注热点。同时，以往研究表明皮质醇能够调节情绪相关的脑区中的神经元的生理反应，包括海马/杏仁核和腹侧被盖区。皮质醇觉醒反应作为一种特有的叠加于基础皮质醇昼夜节律之上的神经内分泌现象，其影响因素及其与认知/情绪的关系，受到了学术界越来越广泛的关注。然而，以往关于皮质醇觉醒反应与认知/情绪之间关系的研究大多都是关注作为特质的皮质醇觉醒反应，很少有研究探讨作为状态的皮质醇觉醒反应与认知/情绪之间的关系。此外，对于认知/情绪功能则大多关注外显行为，对背后的神经机制探索较少。本研究在既往的文献背景和本实验室前期研究的基础上，利用皮质醇觉醒反应这个心理生理指标，结合行为和事件相关电位技术，通过系列研究，检验健康成年人皮质醇觉醒反应与当天下午的脑功能之间的关系。

研究一旨在考察皮质醇觉醒反应和静息态脑电之间的关系。在实验中以静息态EEG考察不同频段能量。结果发现早晨的CAR和额中线theta波能量显著正相关，这可能说明早晨的CAR越大，白天的额叶功能越好。接下来，我们将采用认知范式来考察CAR与任务态脑功能的关系。

研究二旨在考察皮质醇觉醒反应和期待加工之间的关系。在实验中以持续性注意(Continuous performance test, CPT)任务考察期待加工能力。结果发现早晨的CAR和行为成绩和晚期伴随性负波(contingent negative variation, CI}TV)波幅负相关。该结果表明了CAR能够预测下午的期待相关脑功能，早晨的CAR越高，被试对即将来临的刺激及反应的准备越弱，相应的行为成绩越差。

研究三A旨在考察皮质醇觉醒反应和反应抑制之间的关系。在实验中以Go/NoGo任务来考察反应抑制能力。结果发现早晨的CAIN和NoGo试次的误报率显著负相关。同时，CAR越大，NoGo-N2的峰波幅也越大。该结果表明早晨的CAR越高，当天下午的反应抑制功能越好，对反应冲突的监控强度越大。研究三B同样以Go/NoGo任务考察了皮质醇觉醒反应和错误加工之间的关系。结果发现CAR和ERA波幅显著正相关，表明早晨的CAR越大，当天下午对错误的监控强度越大。此外，皮质醇觉醒反应还能够正向预测错误后Go试次的P3峰波幅，表明早晨的CAR越高，下午对错误后事件分配的资源越多，错误后加工能力越强。

研究四旨在考察皮质醇觉醒反应和情绪反应之间的关系。在实验中通过被动观看任务考察负性情绪晚期加工阶段的神经活动，并用正性负性情绪量表（Positive Affect and Negative Affect Scale, PANAS）采集被试看到情绪图片前后正负性情绪的变化。结果发现CAR和PANAS量表测得的负性情绪的变化显著负相关。CAR和晚正电位(late positive potential, LPP) LPP差异波没有显著相关。该结果表明早晨CAR越大，当天下午负性情绪图片引起的情绪变化越小。

本研究首次通过事件相关电位(Event7related potential, ERP)手段研究了健康人群早晨的CAR和当天下午的脑功能之间的关系。研究一、三、四从不同角度一致发现，CAR能够正向预测下午的脑功能，较高的CAR意味着较好的认知能力和较低的负性情绪反应。但研究二的结果则显示CAR与认知脑功能的关系可能不是单维的，较高的CAR也可能意味着较低的行为前预备和行为成绩。本研究的研究结果不仅有助于理解CAR作为生物标记物在心理生理学研究中的作用，也为提前预判特殊岗位人员的执行任务时的脑功能提供了潜在的科学途径。

The cortisol awakening response (CAR) is the rapid increase of cortisol levels after awakening in the morning. It was first identified as a "reliable biomarker of adrenocortical activity" and it is characterized by marked interindividual variability. There is accumulating additional evidence describing marked intraindividual state variation in the CAR. The cortisol, as the product of hypothalamic-pituitary-adrenal (HPA) axis, its relationship between cognition has been a hot topic in the field of stress. The cortisol awaking response, as a kind of neuroendocrine phenomenon superimposed on basal cortisol cycle, it's relationship between cognitive function has attracted growing attention over the last two decades. At the same time, previous studies have demonstrated that corticosterone has direct modulatory effects on the physiological responsiveness of neurons in neural structures associated with emotion, such as the hippocampus, amygdala and ventral tegmental area. However, little is known about daily variation in the CAR and cognitive/emotion function. Furthermore, most of knowledge has been derived from studies of on behavioral result rather than brain function. Based on the previous research on this topic and former studies of our group, we combined behavioral and event-related potential to examine the relationship between CAR and the brain function.

In the first study of the paper9 we examined whether the cortisol awakening response predict resting state EEG. The results showed that the CAR was associated with power of the middle frontal theta on this same day. This result may indicate that the greater CAR in the morning, the better frontal function throughout the dad. Therefore, we will use cognitive paradigm to investigate the relationship between CAR and task-based brain function.

The aim of the study 2 was to investigate whether the CAR predicted the anticipation function on the same day. Participants performed the CPT task while electroencephalograms (EEG) were recorded in the afternoon of the same day. The results showed that the CAR was negatively related both behavior and amplitude of CNV2. Our findings suggested that the CAR was predictive of the brain function of anticipation in on the same day. The greater CAR in the morning was associated the weaker preparation for the upcoming stimulus and response, and the corresponding worse the behavioral performance.

The aim of the study 3A was to investigate whether the CAR predicted the response inhibition function on the same day. Participants performed a Go/NoGo task while electroencephalograms (EEG) were recorded in the afternoon of the same day. The results showed that a greater CAR was associated with a stronger N2. Furthermore, the CAR was negatively related to the false alarm rate of NoGo-trials. Our findings suggested that the CAR was predictive of the function of response inhibition in both behavioural performance of response inhibition and the the conflict monitoring on the same day in healthy men. The aim of the study 313 was to investigate whether the CAR predicted the error processing function on the same day in both behaviour and the dynamic time course of brain processing. The method was same with the study 3A. The results showed that a greater CAR was associated with a stronger ERIN，indicating the greater monitoring ability in the afternoon. The CAR was also positively related to P3 of post-error Go-trials. Our findings suggested that the greater CAR was predictive of more resources allocated to post-error events and better function of error processing function on the same day in healthy men.

Finally, in the last study of the paper, we investigated whether the CAR predicted negative emotional response in the same day. The Passive viewing task was used to measure negative emotional response. Furthermore, we examined emotion response from PANAS, which contained two emotions (positive and negative). The main result was a significant negative correlation between CAR and negative emotion increase. We did not find a significant relationship between CAR and LPP. Our results support the hypothesis that greater CAR was associated the smaller change in negative emotion response.

This is the first study to examine the relationship between the CAR and daily brain functioning utilizing ERP The results of study 1,3,4 showed that CAR could positively predict the brain function in the afternoon. The greater CAR indicated better cognitive ability and less negative emotional response. However, the results of study 2 may indicate that the CAR was not linearly related to cognition and brain function, the greater CAR was associated worse preparation and the behavioral performance in the afternoon. The results of these issues not only help illuminate the utility of the CAR as a promising biomarker in psychophysiological research, but also provide a good scientific basis for brain function when perfoming tasks of special staff.