Frontal synchronisation facilitates taxonomic priming: insights from N400 source estimation and functional connectivity

This study explored the cortical sources and functional connections underlying the N400 in relation to taxonomic priming. High-density EEG was recorded in 60 neurotypical individuals during an auditory categorical priming task. eLORETA source estimation was performed. Functional connectivity specific to the processing of primed and unprimed words was calculated between 68 × 68 ROI pairs. Significant N400 activation clusters were identified in an early time window (460–510 ms) in the left frontal cortex (orbitofrontal, pars opercularis, pars triangularis, precentral), and in a middle time window (520–570 ms) in the left posterior cingulate cortex. Significant connections for the processing of primed versus unprimed words were identified within the left frontal lobe, between left and right frontal cortices, and between left frontal and parieto-occipital cortices. Functional synchronisation between frontal areas facilitates the top-down retrieval of lexical-semantic representations for primed words. This enhanced connectivity likely drives local frontal activation reductions for primed compared to unprimed word processing.

本研究探讨了与分类启动（taxonomic priming）相关的N400（N400）成分的皮层起源及其潜在功能连接机制。研究招募60名神经典型个体，在其完成听觉类别启动任务期间采集高密度脑电（EEG，Electroencephalogram）信号，并采用eLORETA（eLORETA）进行脑电源定位估计。针对启动词与非启动词加工的特异性功能连接，本研究在68×68的感兴趣区（ROI，Region of Interest）对之间进行了计算分析。结果显示，在早期时间窗口（460–510 ms）的左侧额叶皮层（眶额叶、额下回岛盖部、额下回三角部、中央前回），以及中期时间窗口（520–570 ms）的左侧后扣带皮层中，均识别出具有统计学意义的N400激活簇。针对启动词与非启动词加工的显著性功能连接主要包括三类：左侧额叶内部的功能连接、左右侧额叶皮层之间的功能连接，以及左侧额叶与顶枕皮层之间的功能连接。额叶区域间的功能同步化可自上而下促进启动词的词汇-语义表征提取，而相较于非启动词加工，这种增强的功能连接或可导致启动词加工过程中的局部额叶激活水平降低。