Experiment 2: Source estimation.

Defining the brain mechanisms underlying initial emotional evaluation is a key but unexplored clue to understanding affective processing. Event-related potentials (ERPs), especially suited for investigating this issue, were recorded in two experiments (n = 36 and n = 35). We presented emotionally negative (spiders) and neutral (wheels) silhouettes homogenized regarding their visual parameters. In Experiment 1, stimuli appeared at fixation or in the periphery (200 trials per condition and location), the former eliciting a N40 (39 milliseconds) and a P80 (or C1: 80 milliseconds) component, and the latter only a P80. In Experiment 2, stimuli were presented only at fixation (500 trials per condition). Again, an N40 (45 milliseconds) was observed, followed by a P100 (or P1: 105 milliseconds). Analyses revealed significantly greater N40-C1P1 peak-to-peak amplitudes for spiders in both experiments, and ANCOVAs showed that these effects were not explained by C1P1 alone, but that processes underlying N40 significantly contributed. Source analyses pointed to V1 as an N40 focus (more clearly in Experiment 2). Sources for C1P1 included V1 (P80) and V2/LOC (P80 and P100). These results and their timing point to low-order structures (such as visual thalamic nuclei or superior colliculi) or the visual cortex itself, as candidates for initial evaluation structures.阐明初始情绪评估背后的大脑机制，是理解情感加工过程的关键却尚未被充分探索的核心线索。事件相关电位（Event-related Potentials, ERPs）因其特别适配该问题的研究需求，在两项实验中被用于数据采集（样本量分别为n=36和n=35）。本研究呈现了情绪效价为负性（蜘蛛）与中性（车轮）的轮廓刺激，并对二者的视觉参数进行了严格标准化处理。在实验1中，刺激物呈现在中央注视点或外周视野（每种条件、每个位置各200试次）：前者可诱发出N40（39 ms）与P80（或称C1：80 ms）成分，后者仅诱发出P80成分。在实验2中，刺激物仅呈现在中央注视点（每种条件各500试次），同样观测到N40（45 ms）成分，随后出现P100（或称P1：105 ms）成分。分析结果显示，两项实验中负性蜘蛛刺激的N40-C1P1峰峰值均显著高于中性刺激；协方差分析（Analysis of Covariance, ANCOVAs）表明，此类效应并非仅由C1P1成分单独介导，N40背后的神经加工过程同样发挥了显著贡献。源定位分析显示，N40的神经源头主要集中于V1区（实验2中该结果更为显著）；C1P1成分的神经源头则包括V1区（对应P80）与V2/侧枕叶复合体（Lateral Occipital Complex, LOC，对应P80与P100）。上述结果及其出现的时间进程表明，低级视觉加工结构（如视觉丘脑核团或上丘）或视觉皮层本身，即为初始情绪评估的潜在神经基础。