The expected target/nontarget condition effects were clearly evident, particularly for the tonal task in healthy adults (Figure 1, left), revealing frontocentral N2 sinks (approximate peak latency 230 ms; e.g., site F4) and mid-parietal P3 sources (375 ms; Pz) for target stimuli only. However, target-related N2 sinks and P3 sources were smaller in patients (Figure 1, right). In contrast, a late mid-frontal sink for targets (480 ms; Fz), which we have repeatedly observed in various paradigms48,53,55,56 and linked to a frontal response negativity (FRN),53 was equally robust in controls and patients. Across tasks, a prominent frontocentral N1 sink corresponded to a lateral temporoparietal source (105 ms; e.g., see sites Cz, C3/4, FC5/6 and TP9/10, P9/10), although this was smaller for syllables compared to tones. This early frontocentral N1 sink was followed by lateral temporal N1 sinks for tones (160 ms; T7/8) but not for syllables.
