The spatiotemporal dynamics of early attention processes: a high-resolution electroencephalographic study of N2 subcomponent sources.

The N2 subcomponents of event-related potentials are known to reflect early attentional processes. The anterior N2 may reflect conflict monitoring, whereas the posterior N2 may be involved in target detection. The aim of this study was to identify the brain areas involved in the generation of the N2 subcomponents, in order to define the spatiotemporal dynamics of these attentional processes. We recorded 128-channel electroencephalograms in 15 healthy controls performing a three-stimulus visual oddball task and identified standard-, distracter- and target-elicited N2 components. Individual N2 sources were localized using standardized-weighted-low-resolution-electromagnetic-tomography (swLORETA). Comparative analyses were performed with a non-parametric permutation technique. Common N2 generators were observed in the Brodmann area (BA) 24 of the anterior cingulate cortex (ACC). The posterior cingulate cortex and the central precuneus were more involved in distracter processing, whereas the anterior precuneus and BA 32 of the ACC were target-specific. In accordance with previous demonstration of the frontoparietal cortex's critical role in attentional processes, these new data shed light on the ACC's role in conflict monitoring and its interaction with other median and frontoparietal structures in early attentional processes.