In previous binaural and dichotic oddball tasks, we restricted our analysis of target-related P3b sources to parietal sites (e.g., Kayser & Tenke, 2006b; Tenke et al., 2008; but for an alternative, see Kayser, Tenke, Gates, & Bruder, 2007). In the present study, the target P3b source (343) was best defined at the five medial parietal sites (Pz, P1/2, P3/4). However, this source topography extended into lateral sites, requiring an additional ANOVA to probe source asymmetries using seven homologous pairs (TP7/8, P7/8, P5/6, P3/4, P1/2, PO7/8, PO3/4). The corresponding mid-frontocental source of factor 343 consisted of four sites: AFz, Fz, F1/2. Finally, F – CP + (542) was measured at five sites for the mid-frontocental sink (FCz, Fz, F1/2, FCz) and four homologous pairs for the centroparietal source (CP1/2, CP3/4, P1/2, P3/ 4). In addition to these regions, the novelty response also included a novelty vertex source for factor 241 (FCz, Cz, C1/2, CPz), and a secondary lateral frontal source topography (AF7/8, F7/8). ANOVA models for each of the midline topographies included group (patient, control) as a between-subjects factor and site
