Our initial reports using this design in healthy adults focused on the methodological comparison of PCA solutions derived from ERP or CSD waveforms (n = 66),48 and the suitability of using these methods for both high- and low-density EEG montages (n = 17).49 The task- and response-related findings of these prior reports provide the groundwork for the current study. Three CSD components represented the target-related N2/P3 complex: 1) an N2 sink, which showed task-dependent topographic maxima with opposite hemispheric asymmetries (tones: frontotemporal R > L; syllables: parietotemporal L > R); 2) a mid-parietal P3 source, which also showed task-dependent, asymmetric enhancements; and 3) a mid-frontal sink accompanied by centroparietal sources occurring around the time of the subjects’ response to targets. The CSD component structure therefore clearly separated a classical P3b positivity from an overlapping anterior negativity.27 While response mode modulated the earlier task-dependent effects, or substantially altered their overall amplitude, an intriguing finding was a selective enhancement of source activity over left lateral temporal sites only for silent count (cf. Figure 8 in Kayser et al.48). This effect was associated
