Despite this degree of consistency with the CSD-PCA factor structure produced in other oddball tasks, there were notable differences. Compared to the other tasks using tonal stimuli, the target N2 sink (241) was shifted medially, with maximal sink amplitude at the frontal midline (Figure 3b, column 3, factor 241). The frontal P3 source was only observed for the novelty oddball task, and was concurrent with parietal P3b (343; Figure 3b, row 2, column 4, factor 343). Although the frontal P3 source (343) was also present for novel stimuli, the only P3 source that was unique to novel stimuli was the novelty vertex source (factor 241; Figure 3b, row 3, column 3; Table 2), which was preceded by a midline novelty N2 sink.3
