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 x 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.