【作者】 孙金燕；

【导师】 骆清铭； 龚辉；

【作者基本信息】 华中科技大学 ， 生物医学工程， 2013， 博士

【摘要】 注意是人类重要的认知功能之一。人的学习、生活和工作中会涉及多种认知功能，其中注意功能非常关键，注意功能的异常与多种疾病密切相关，因此对注意神经机制的研究具有很重要的意义。本文围绕注意的定向和执行控制两个组成成分展开研究。对于注意定向，采用脑电技术考察了视觉空间注意定向对刺激处理的影响和威胁情绪对注意定向的影响。对执行控制，采用近红外光谱术（NIRS）和脑电技术结合的光电联合手段考察了Stroop任务中执行控制的神经机制。主要的研究内容和结论如下：（1）在持续性注意条件下的线索-目标任务中，结合事件相关电位（ERP）和事件相关振荡（ERO）两种分析，考察视觉空间注意定向对刺激处理的影响。结果发现有效刺激P1幅度比无效刺激更正。有效刺激theta频段功率显著增加，且大于无效刺激，说明theta频段可能表征注意资源的多少。alpha频段在注意视野同侧后部脑区功率显著增加，体现了一种主动抑制机制。视觉空间注意对beta频段的调节与alpha频段相似，说明beta频段可能反映了与alpha频段类似的机制。结果说明视觉空间注意通过增强注意刺激的处理和抑制干扰刺激两种机制的结合影响刺激的处理。（2）情绪点探测任务中结合ERP和ERO两种分析，考察威胁情绪相对于愉悦情绪的注意偏向。情绪线索呈现500ms时，威胁线索诱发的N1成分比愉悦线索更负，该效应在额中区最大；威胁线索诱发的theta频段功率的增加大于愉悦线索，这一效应在后部脑区显著。N1结果表明对威胁情绪的处理偏向与早期注意处理相关，theta结果支持了后部脑区theta同步性反映对刺激情绪意义的评估。ERP和ERO结果从不同的方面说明了注意能够更多地定位到威胁情绪线索。（3）联合NIRS和脑电技术，同步测量颜色-字匹配Stroop任务中的血氧响应和电生理响应，以考察执行控制的神经机制。结果发现反应时和晚正复合波（LPC）的Stroop效应上存在性别差异。LPC的Stroop效应只对女性被试显著，且与女性被试较大的反应时Stroop效应正相关。说明LPC反映字义的额外处理，女性被试进行了更精细的语义分析，贡献于其更大的反应时Stroop效应。N450的Stroop效应出现在不一致刺激的行为反应之前，且它与前额叶氧合血和蛋白（HbO2）的Stroop效应负相关。具体为左侧前额叶HbO2的Stroop效应与N450前段（440-580ms）的Stroop效应负相关，而双侧前额叶HbO2的Stroop效应与N450后段（600-680ms）的Stroop效应负相关。这说明N450反映冲突探测和解决，左侧前额叶可能参与冲突探测，而双侧前额叶参与冲突解决。本研究加深了对注意定向和执行控制神经机制的理解，同时对研究疾病注意功能的异常有积极的指导意义。更多还原

【Abstract】 Attention is an important cognitive function for humans. It is critical for study, life,work and any cognitive process of human beings. Abnormal attention is closely relatedwith many diseases. Thus, it has great significance to investigate the neural correlates ofattention.This study focused on two components of attention: orienting and executive control.As to orienting, the influence of visuospatial attention orienting on stimulus processingand the influence of threatening emotion on orienting were investigated with event-relatedelectroencephalography (EEG). Regarding executive control, the neural correlates ofexecutive control was investigated with a multi-modality optical-electrophysiologymethod combining near-infrared spectroscopy (NIRS) and event-related EEG in a Strooptask. The main research contents and innovation are as follows:(1) The influence of visuospatial attention orienting on stimulus processing wasinvestigated by combining event-related potential (ERP) and event-related oscillation(ERO) analyses. The mean amplitude of P1was more positive for valid stimuli thaninvalid stimuli. Valid stimuli led to significant power increase in theta, alpha and beta. Thepower increase in theta for valid stimuli was significantly larger than that for invalidstimuli, which indicates that theta might reflect how much visuospatial attention isallocated. Alpha power increase in the posterior region ipsilateral to the attended positionreflects an active suppression mechanism. The attention modulation on beta was similar toalpha, which indicates that beta might reflect a similar mechanism to alpha. These resultsindicate that visuospatial attention influences the stimulus processing by both facilitatingthe attended stimuli and inhibiting the unattended stimuli under sustained attention.(2) The attentional bias of threatening emotion relative to pleasant emotion wasinvestigated in an emotional dot probe task by using both ERP and ERO analyses.Emotional cues showed for500ms. The mean amplitude of N1was greater negative forthreatening cues than pleasant cues with the most significant effect in the fronto-central region, indicating a processing bias for threat related to the early attention processing. Thetheta synchronization was stronger for threatening cues than pleasant cues with significanteffect in posterior regions, suggesting that the posterior theta synchronization reflects theevaluation of emotional significance of stimuli. Taken together, these results indicate thatattention is more oriented toward threatening information and ERP and ERO analysesprovide some independent insights into the attentional bias for threatening emotion.(3) The hemodynamic and electrophysiological responses in a color-word matchingStroop task were simultaneously measured by combining NIRS and ERP to study theneural correlates of executive control. There were gender differences in the Stroop effectsof response time (Stroop_RT) and late positive complex (Stroop_LPC). The Stroop_LPCwas only significant in females. The results show that LPC is associated with additionalprocessing of word meaning, and females conduct more elaborate semantic processingwhich might contribute to their larger Stroop_RT. The significant N450Stroop effectoccurred before the behavioral response to incongruent stimuli, and it was negativelycorrelated with the oxy-hemoglobin (HbO2) Stroop effect. More specifically, the HbO2Stroop effect in the left prefrontal cortex (PFC) was negatively correlated with the N450Stroop effect during the early phase (440-580ms), while the HbO2Stroop effect in thebilateral PFC was negatively correlated with the N450Stroop effect during the later phase(600-680ms). The results indicate that:(1) there are two stages in N450: conflict detectionand resolution;(2) left PFC may be involved in conflict detection and bilateral PFC isengaged in conflict resolution.This study provides insights into the neural correlates of attention orienting andexecutive control, and gives practical guidance for studying the abnormal attention ofdiseases.更多还原