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慢性应激对执行功能的影响:ERP 研究
其他题名The Effects of Chronic Stress on Executive Functions: An ERP Study
袁怡然
学位类型博士
导师张侃 ; 吴健辉
2014-05
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业心理学
关键词慢性应激 执行功能 事件相关电位
摘要在日常生活中,人们不可避免的会遇到各种应激的挑战。短期适度的应激能够有利于个体的生存。但是长期或过度的应激,就会给人的生理和心理带来不良的影响。应激源通过激活下丘脑-垂体-肾上腺轴(HPA 轴)释放肾上腺皮质激素,后者又返回到中枢神经系统,影响靶脑区的结构和功能,主要包括前额叶、杏仁核和海马,进而影响认知和情绪,比如导致记忆能力的降低、行为决策的偏差和情感系统的紊乱。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,尤其是在面临环境改变和应激的状态下。因此研究慢性应激对执行功能的影响具有重要的意义。
目前关于慢性应激对人类执行功能影响的研究主要集中在行为上,神经机制的研究相对还比较少,且研究方法比较单一,多是功能磁共振成像研究。而事件相关电位技术具有毫秒级的时间分辨率,可以为我们提供更好的技术手段以了解慢性应激对执行功能影响的脑机制。因此本论文以经历长期考试(考研)准备作为慢性应激源,以应激觉察量表和皮质醇觉醒反应作为评定慢性应激的主客观指标,采用事件相关电位技术,考察慢性应激对工作记忆、反应抑制和错误加工这三种执行功能的神经动态加工过程的影响。
本论文的具体研究结果如下:
(1)考研组被试的应激觉察量表得分高于非考研组,说明考研组被试的确长时间地暴露于较高水平的应激状态下。考研组的皮质醇觉醒反应低于非考研组,说明长期的备考导致了神经内分泌资源的过度耗竭,进一步证明了考研组被试经历了较高水平的慢性应激。
(2)慢性应激增加了n-back 工作记忆任务中注意分配阶段的神经活动,体现在与注意资源分配有关的P2 波幅的增加,且P2 波幅的效应只体现在考研高应激组上。被试感知到的应激水平越高,P2 的波幅也就越大。即使考研组被试消耗了更多的神经资源,却和非考研组被试具有相同的外显行为绩效,说明慢性应激导致了工作记忆的神经效能的下降。
(3)相关结果显示对于考研组,被试感知到的慢性应激水平越高,对反应冲突的监控速度就越慢,体现在NoGo-N2 潜伏期的延长。
(4)在错误监测阶段,考研组比非考研组诱发了更大的错误反应后的Pe波幅。而且被试认为正在准备的考试的重要性越大,Pe 波幅就越大,说明慢性应激导致了错误后更大的情绪反应和动机评估。
(5)而在错误反应后的行为调整阶段,考研组被试比非考研组的P3 波幅下降,说明慢性应激导致了错误后的注意资源变少,行为调整能力降低。
本论文的研究结果不仅有助于我们更好地了解有关慢性应激对执行功能的神经动态加工过程的影响规律,也为应激评估和干预提供科学指标和理论基础。
其他摘要In our daily life, we will inevitably meet a variety of stress. The short-term or moderate stress is benefit to an individual’s survival, while long-term stress or chronic stress has adverse effects on people’s physiology and psychology. 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, mainly including the prefrontal cortex, amygdale and hippocampus. Hence, stress has impacts on cognition and emotion. For example, stress can impair memory, behavioral decision and leads to emotional disorder. 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 stress. Thus it is important to examine the effects of chronic stress on executive
functions.
The researches which were about the effects of chronic stress on executive function mainly focused on the behavior. Neuroscience study gets less attention. Moreover, the method is unitary; most of stress studies were functional magnetic resonance imaging studies. 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 stress exposure.
Therefore, the purpose of the current research was to investigate how chronic stress effects on executive functions by using the event-related potentials technique. We used preparation for a major examination (National Postgraduate Entrance Exam, NPEE) as a chronic stressor. The perceived stress scale and cortisol awakening response were collected to assess the level of chronic stress. We focused on three executive functions, including working memory, response inhibition and error  processing.
The main results were as follows:
(1) Psychological assessments confirmed that participants in the exam group were indeed exposed to high levels of perceived stress. Endocrinal results revealed a significantly decreased CAR in the exam group compared with the non-exam group, which suggests that exposure to chronic stress leads to reduced adrenocortical activity.
(2) Chronic stress may increase the neural activity of the stage of attention allocation in n-back WM task, reflecting on increased P2 amplitude. Furthermore, the group difference in P2 amplitude was most pronounced in participants in the exam group who reported high levels of perceived stress. Correlation analyses showed that the perceived stress score was positively correlated with the P2 amplitude. Instead of better behavioral performance, the exam group used more neural resources to maintain a similar performance with the non-exam group, which may indicate that chronic stress decreases neural efficiency while performing a WM task.
(3) Correlation analyses showed that the higher level of stress, the slower the speed of conflict detection in response inhibition, which reflecting on prolonged the latency of NoGo-N2. And this correlation only occurred in the exam group.
(4) The exam group showed increased Pe amplitude compared with the non-exam group after committing an error. Participants’ rating of the importance of the exam was positively associated with the amplitude of Pe. These results suggest that chronic stress leads to greater motivational assessment of and higher emotional response to errors.
(5) Chronic stress may lead to the decrease of the attention resource after committing an error, which reflected on attenuated P3 amplitude in post-error condition.
This research not only facilitates the understanding of the effects of chronic stress on executive functions, but also provides scientific indicators and theoretical basis for stress assessment and intervention.
学科领域应用心理学
语种中文
文献类型学位论文
条目标识符http://ir.psych.ac.cn/handle/311026/19750
专题健康与遗传心理学研究室
作者单位中国科学院心理研究所
推荐引用方式
GB/T 7714
袁怡然. 慢性应激对执行功能的影响:ERP 研究[D]. 北京. 中国科学院研究生院,2014.
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