In contrast, robust group and condition differences were found for late stimulus-locked CSD factors (N2 sink, P3 source). Across modalities, the vertex N2 sink was significantly reduced in patients compared to controls (cf. factors 385 and 270 in Figures 5C and 5D; Table 3). The vertex N2 sink was also greater for old than new visual stimuli.6 Likewise, the analysis for the auditory N2 sink at medial central sites yielded a strong group difference, an old-greater-than-new condition main effect (M ± SD, old = −0.76 ± 1.04, new = −0.62 ± 0.98), and a left-greater-than-right hemisphere main effect (cf. factor 385 in Figure 5C; Table 3A). Although there was only a marginally significant group × hemisphere interaction, a significant simple hemisphere main effect was observed for controls, F(1, 38) = 14.2, p = .0006 (M ± SD, C3 = −1.57 ± 0.78, C4 = −0.90 ± 1.00), but not patients, F(1, 38) = 1.09, p = .30 (M ± SD, C3 = −0.24 ± 0.76, C4 = −0.05 ± 0.68).
