抑郁倾向个体的负性记忆抑制

发布时间：2018-10-09 13:14

【摘要】：以往研究表明,抑郁个体常常受到不愉快记忆或想法的侵入和打扰,他们对负性记忆的主动抑制功能受损。为了明确抑郁损伤记忆抑制功能的神经机制,本文采用事件相关电位(ERP)技术分别考察了抑郁倾向个体在编码和提取阶段的记忆抑制任务上的表现。编码阶段,本研究采用项目法定向遗忘范式考察了高低抑郁倾向被试在中性和负性词上的定向遗忘效应及其相应的大脑电生理活动。结果表明,低抑郁倾向被试在中性和负性材料上都表现出了定向遗忘效应;而高抑郁倾向被试只在中性材料上产生了定向遗忘效应,对于负性材料,他们存在遗忘困难。脑电结果显示,相比于低抑郁组,高抑郁倾向被试在被动观看负性词时产生了更大的P2和LPP,而在抑制负性材料的编码时则产生了更大的P1和N2。这些结果共同提示,高抑郁倾向个体在初级感知阶段对负性材料有着更多的选择性注意和加工,而在主动抑制负性材料的编码时,虽然他们调用了更多的认知资源、付出了更大的认知努力,但他们还是失败了,表明他们在抑制控制机制上的效能低于常人。提取阶段,本研究采用想和不想范式考察了高低抑郁倾向被试在中性和负性材料有意提取和提取抑制上的行为成绩及大脑电生理活动。结果表明,高抑郁倾向被试在记忆的提取上表现出了“心境一致性”的倾向:相比于低抑郁组,高抑郁倾向被试在回想负性记忆条件下产生了更大的LPC,而在抑制回想负性记忆条件下产生了更小的N2,表明他们对负性记忆有着主动提取优势并且其对已经进入长时记忆的负性信息有着低于常人的抑制动机,因此难以抑制负性记忆的提取。通过上述两个实验,本研究发现,在编码阶段,高抑郁倾向个体在自下而上的选择性注意和自上而下的抑制控制机制上都存在异常,并且这两种机制上的缺陷共同导致了他们在抑制负性材料编码时的失败。而在提取阶段,高抑郁倾向个体对负性记忆有着提取优势和抑制困难。正是这种记忆编码和提取上的异常使得他们倾向于对生活中的负性事件进行持续性的反刍而难以自控,从而进一步加剧抑郁的心境,造成负性情绪与负性反刍之间的恶性循环。然而,由于本研究所选用的被试为抑郁倾向个体而非临床抑郁患者,因此使用这一研究结果进行推论时应格外谨慎。
[Abstract]:Previous studies have shown that depressed individuals are often invaded and disturbed by unpleasant memories or thoughts, and their active inhibition of negative memory is impaired. In order to elucidate the neural mechanism of memory suppression in depressive patients, event-related potential (ERP) technique was used to investigate the memory suppression tasks of individuals with depression tendency at the coding and extraction stages. At the coding stage, the study investigated the directional forgetting effect and the corresponding electrophysiological activities of the subjects with high or low depression tendency on neutral and negative words. The results showed that the subjects with low depression tendency showed directional forgetting effect on both neutral and negative materials, while those with high depression tendency only had directional forgetting effect on neutral materials, and they had difficulty forgetting in negative materials. EEG results showed that compared with the low depression group, the subjects with high depression tendency produced larger P2 and LPP, when they watched the negative words passively, and produced larger P1 and N2 when they inhibited the encoding of negative materials. Together, these results suggest that individuals with a high tendency to depression have more selective attention and processing of negative materials at the primary stage of perception, while actively suppressing the coding of negative materials, although they call on more cognitive resources. Greater cognitive effort has been made, but they have failed, suggesting that they are less effective than normal in restraining control mechanisms. In the extraction stage, the behavioral scores and brain electrophysiological activities of subjects with high or low depression tendency were investigated by intentional extraction and inhibition of neutral and negative materials. The results showed that the subjects with high depression tendency showed a tendency of "mood consistency" in memory extraction: compared with the low depression group, The subjects with high depression tendency produced larger LPC, under recall negative memory condition and smaller N 2 under inhibition recall negative memory condition, indicating that they had active extraction advantage of negative memory and their pair had entered long. The negative information of time memory has lower inhibition motivation than normal people. Therefore, it is difficult to suppress the extraction of negative memory. Through the above two experiments, we found that in the coding stage, individuals with high depressive propensity were abnormal in the bottom-up selective attention and top-down inhibition control mechanism. And these two mechanisms together lead to their failure to suppress negative material coding. In the extraction stage, individuals with high depressive tendency had the advantage of extraction and inhibition of negative memory. It is this kind of abnormal memory coding and extraction that makes them tend to regurgitate continuously in their life, which makes it difficult to control themselves, thus further exacerbating the depressed mood and creating a vicious circle between negative emotion and negative ruminant. However, since the subjects selected in this study were individuals with a tendency to depression rather than clinically depressed patients, the findings should be extrapolated with caution.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：B842.3

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