健康与遗传心理学研究室知识库

     文献表明应激可激活下丘脑一垂体一肾上腺皮质(hypothalamic- pituitary-adrenal, HPA)轴和交感神经系统( sympathetic nervous system, SNS )，导致外周糖皮质激素( glucocorticoid)和儿茶酚胺(catecholamine)递质水平升高。应激可对一记忆功能产生影响，但是应激反应中HPA轴和SNS的激活与记忆不同阶段的关系尚无系统研究。为进一步探讨HPA轴和SNS在应激影响一记忆功能中的作用模式，采用相关研究方法，研究应激对一记忆不同阶段的影响及其与HPA轴和SNS反应的关系。研究包括以下两个部分:
    第一部份首先采用负性情绪图片刺激，研究这一被动性情绪应激模式下健康女大学生HPA轴(指标为唾液皮质醇)和SNS(指标为血压和心率)的反应，随后依次观察这一情绪刺激对记忆和注意成绩的影响，并且探讨HPA轴和SNS在其中的作用，结果如下:
    1负性情绪图片刺激可诱发被试明显的负性情绪反应，激活SNS和HPA轴，表明这一情绪刺激材料可在实验室中作为情绪应激模式用于人类研究;
    2采用学习一v己忆研究范式，发现负性情绪图片刺激可提高记忆成绩，这一作用与SNS反应呈正相关;但皮质醇反应与一记忆成绩呈负相关;
    3负性情绪图片刺激可提高注意成绩，并与SNS反应呈正相关;皮质醇反应与第一分钟注意成绩呈负相关;
    第二部份分别研究负性情绪图片刺激对一记忆编码、巩固、提取阶段的影响，进一步探讨HPA轴和SNS在其中的作用，结果如下:
    1记忆编码前负性情绪图片刺激可提高一记忆成绩，并与SNS反应呈正相关，与皮质醇变化无明显相关;
    2一记忆巩固阶段负性情绪图片刺激可提高一记忆成绩，皮质醇反应与一i己忆成绩呈正相关，但SNS反应与t记忆成绩呈负相关;
    3记忆提取前负性情绪图片刺激对一记忆成绩无明显影响，但皮质醇反应与记忆成绩呈负相关。
    以上结果表明，负性情绪图片刺激可诱发明显的情绪应激反应，激活HPA轴和SNS的功能。而HPA轴和SNS激活在记忆编码、巩固、提取的过程中可能发挥不同的作用。较高水平SNS兴奋可促进其记忆编码，但损害其记忆巩固;HPA轴反应则可促进记忆巩固、一损害记忆提取。

    Previous studies demonstrated that stress activated both the hypothalamic-pituitary-adrenal (I:PA) axis and the sympathetic nervous system (SNS),increased the levels of peripheral glucocorticoid and catecholamine. Glucocorticoid and catecholamine secreted during stressful events may affect memory function. To further clarify the roles of HPA axis and SNS in stress-induced changes of memory performance, the present study investigated the effects of passive emotional stress on different memory phases and the relationship with  neuroendocrine  function.Experiments were divided into two parts.
    In the first part, HPA axis (indexed by salivary cortisol level)and SNS (indexed by blood pressure level and heart rate) reactions to negative affective picture stimuli were examined in healthy female college students. Then the effects of negative emotional stress on memory and attention performances and the relationship with HPA axis and SNS responses were investigated. Results are as follows:
    1 Negative affective picture stimuli induced negative emotional responses and increased peripheral blood pressure level and salivary cortisol level, suggesting both SNS and HPA functions were activated. These results demonstrate that the negative affective picture stimuli can be used in laboratory as a negative emotional stress model.
    2 Negative emotional stimuli increased the recall performance for learn-recall test, in which blood pressure reaction was associated with increased memory performance, suggesting that high SNS activation may facilitate memory performance.Cortisol reaction was associated with decreased memory performance, suggesting stress-induced HPA axis response may impair memory performance.
   3 Negative emotional stimuli increased the attention performance, in which blood pressure reaction was associated with increased attention performance,suggesting that high SNS activation may facilitate attention performance. Cortisol reaction was associated with decreased attention performance, suggesting that stress-induced IIPA axis response may impair attention performance.
    In the second part, experiments were performed to investigate the effects of negative emotional stimuli on memory encoding, consolidation and retrieval process and the relationships with HPA axis and SNS responses. Results are as follows:
    1 .Negative emotional stimuli presented before encoding process increased the memory performance, in which blood pressure reaction was associated with the increased performance, suggesting that high SNS activation may facilitate memory encoding process. HPA axis response seemed not to be associated with memory encoding process.
    2. Negative emotional stimuli presented during consolidation process had complex effects on the memory performance. Cortisol reaction was associated with increased memory performance. But high blood pressure reactions were associated with poor memory performances.
    3. Negative emotional stimuli presented before retrieval process had no significant effect on memory performance. However, cortisol reaction was associated with decreased memory performance.
    In summary, negative affective picture stimuli induced negative emotional responses and activated both SNS and HPA functions. Reactions of HPA axis and SNS induced by negative affective picture stimuli play different roles in the effects of passive emotional stress on memory performance. The high level of SNS activation may increase memory performance of encoding, decrease memory performance of consolidation. Responses of HPA axis induced by negative emotional stimuli may impair memory retrieval process and enhance memory consolidation process.