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催产素对自我参照加工的影响及其神经机制
中文摘要

催产素是人脑中分泌的神经肽物质,影响人类的认知和行为。前人关于催产素对社会认知与行为的影响主要关注催产素如何影响关于他人信息的加工以及与他人的行为互动。关于自我的加工是社会认知的重要组成部分,自我与他人在社会互动中对立统一不可分割,所以催产素是否以及如何影响自我相关加工是一个重要的科学问题。本论文采用自我参照加工实验范式,以行为测量、事件相关电位和功能磁共振成像为研究手段,研究催产素是否以及如何影响自我相关的加工,并揭示催产素影响自我相关加工的神经机制。 在四个研究中,采用双盲操作,被试在实验任务前通过鼻腔施用催产素或生理盐水。在实验任务中被试判断一系列人格形容词是否适合描述自己或他人。研究一记录行为反应,在自我参照编码阶段完成后,被试进行词语再认任务。结果发现,催产素相对于生理盐水缩短了自我判断的反应时,并促进了与自我相关的人格形容词的判断的记忆提取。研究二用事件相关电位记录被试进行自我参照编码过程的神经电活动,与生理盐水相比,催产素降低了参与自我参照编码(与他人参照编码相比)相关的P2和LPP成分的幅值。研究三用功能磁共振成像记录与自我参照编码过程的神经活动,发现催产素降低了表征自我的内侧前额叶活动,同时增强了与外部注意相关的额顶网络的神经活动。研究四用功能磁共振成像方法记录与自我关联词语记忆提取时相关的神经活动,发现催产素增强了自我相关记忆提取时的右侧额叶神经活动,以及在提取成功的条件下,增强表征记忆提取精细程度的海马神经活动。 这些结果表明催产素对自我参照编码阶段和记忆提取阶段产生显著影响。影响自我参照编码的神经机制是催产素降低自我相关的脑电活动以及内侧前额叶的神经活动,同时增强额顶外部注意系统的神经活动。影响记忆提取的神经机制是催产素增强右侧额叶及海马的神经活动。这些结果提示降低自我信息编码是催产素影响社会认知和行为的一个新的机制。本文根据实验结果提出了新的理论模型解释催产素对于社会认知和行为的重要作用,并讨论了催产素治疗自闭症的可能的机理。 关键词:催产素,自我参照,内侧前额叶,功能磁共振成像

英文摘要

Oxytocin (OT) is a peptide hormone produced in human brain and plays an important role in social cognition and social behavior. Previous studies of OT effects on social cognition and social behavior have focused exclusively on other-related processing and behavior. The reciprocally interconnected role of self and other processing in social cognition has been widely documented. Thus it is critical to address how OT affects self-related processing in the human brain. By integrating the self-reference paradigm, event-related potential (ERP),and functional magnetic resonance imaging (fMRI),I investigated whether and how intranasal OT influences self-related processing and the underlying neural mechanisms in the human brain. Using a double-blind, placebo-controlled design, participants were treated with OT or placebo before the experiment tasks. The self-referential processing task required judgments about the personality traits of oneself and specific others. In study 1,after the self-referential encoding phase,participants were given a surprised memory test during which they made judgments on whether they had seen the adjectives in the encoding phase. Results showed that OT resulted in shorter encoding time for selfreferential processing and better memory retrieval of self-related adjectives with more episodic details. In study 2,ERPs were recorded during self-referential encoding phase. OT vs. placebo treatment reduced the amplitudes of P2 and LPP during self-referential processing (compared with other-referential processing). In study 3,using fMRI, neural activities were recorded during self-referential encoding. Results showed that OT decreased the medial prefrontal cortex (MPFC) activity associated with self-referential encoding but increased fronto-parietal network associated with external attention. In study 4,participants were treated with OT or placebo after the self-referential encoding phase and before the memory retrieval task. The neural activity was recorded during memory retrieval using fMRI. OT compared to placebo increased the right medial frontal activity during self-related memory retrieval and increased the neural activity in the hippocampus related to retrieval success. These results suggest that OT affects self-referential processing in both referential encoding and memory retrieval. During self-referential encoding OT decreased the neural activity in the MPFC related to coding self-relevance but increased frontoparietal external attention network. This provides evidence for a new mechanism of OT effects on social cognition and social behavior. These findings extend our understanding of the self-referential processing, propose a new mechanism accounts for the important role of OT on social cognition and social behavior, and have important implications for underlying the translation mechanisms of OT for treatment of autism. KEY WORDS: Oxytocin, Self-reference, MPFC, fMRI

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