视觉靶刺激和干扰子刺激响应过程中的脑电流源模型分析

Brain Electrical Source Analysis of the Response to Visual Target and Distractor Stimuli

采用3-刺激视觉oddball实验范式,研究大脑离散电流源在干扰子刺激和靶刺激响应过程中的电流时间过程。本文采集了健康受试者的64导联头皮脑电(EEG)数据,通过3-刺激范式,既检测到人脑在识别小概率事件(靶刺激和干扰子刺激)过程中产生的P300电位的P3b成分;又测得P300电位的P3a成分,P3a主要在干扰子刺激响应过程中产生。本文用相同实验范式下的磁共振激活簇空间坐标作为约束条件,建立了干扰子刺激和靶刺激事件相关电位(ERPs)的区域源模型,区域源模型的电流计算分析表明P3b的主要神经源包括双侧下顶叶、双侧后顶叶皮层和双侧颞下皮层,而P3a的主要神经源包括双侧脑岛、双侧中央前沟和扣带回等额叶皮层。研究结果表明对靶刺激的脑处理涉及顶叶、颞下皮层和左侧脑岛等参与的刺激驱动注意过程、目标引导注意过程、视觉形状分类与记忆提取等,而对干扰子刺激的脑处理则主要涉及右侧脑岛、扣带回等完成的注意转移、注意资源的重新分配过程。

In this paper, time courses of discrete cortical current sources evoked by target and distraetor stimulus are presented in a visual threestimulus oddball paradigm. 64channel electroencephalogram （EEG） signals were recorded in healthy subjects in the paradigm where the P3b component of the P300 is evoked in the detection of rare events （target and distractor） and the P3a component is mainly produced by distractor events. A regional source model with constraints of spatial coordinates from fMRI was then applied to eventrelated potentials （ERPs） data in the target and distractor conditions. Activities of regional sources indicated bilateral inferior parietal lobe, posterior parietal cortex and inferior temporal cortex mainly contribute to the P3b, while the P3a was mainly produced by bilateral in sula, bilateral preeentral sulcus and cingulate gyrus. Target processing involved parietal lobe, inferior temporal cor tex and left insula engaged in stimulusdriven attention process, goaldirected attention process, categorization of vis ual stimuli and memory retrieval, while distraetor processing involved right insula and cingulate gyrus engaged in at tention switching and reengagement of attention resource.