CSD factors corresponded to N1 sink (peak latency 105 ms; off-midline, medial-central sinks associated with lateral temporoparietal sources; 5.9% explained variance), temporal N1 sink (170 ms, lateral-temporal sinks paired with a vertex source; 6.1%), N2 sink (240 ms, frontocentral sinks for tones and left lateral-parietal sinks for syllables paired with a mid-parietal source; 6.1%), and P3 source (355 ms; broad medial-parietal maximum; 21.3%). Two additional high-variance factors corresponded to late activity around the time subjects responded (560 ms; mid-frontal sink paired with off-midline, centroparietal sources [FRN]; 26.4%) and beyond (895 ms; unsystematic topography; 21.0%). For both groups, these factors closely matched those reported previously for these tasks in larger samples of healthy adults34,48,49; however, patients appeared to have reduced amplitudes of the tonal N2 sink and P3 source across tasks. The use of a common extraction was validated by separate PCA solutions derived from the CSD data for patients only (n = 23) or controls only (n = 23), which revealed highly comparable factor structures (correlations between corresponding factor loadings were .95 ≤ r ≤ .99). Because factors 240, 355,
