The silent count effect was observed during a late CSD factor (560 ms peak latency) interval and was maximum over left temporal sites. While the underlying component is substantially masked in surface potentials, CSD-PCA methods have repeatedly revealed a mid-frontal, response-related negativity (FRN) accompanied by off-midline centroparietal sources during this time interval in a wide range of ERP paradigms – including tonal,34 phonetic,48,49 novelty,56 and dichotic55 oddball tasks, as well as continuous recognition memory tasks using spoken or read words and faces.53,82,84 Thus, the FRN is a characteristic and replicable CSD component. Although this component is observed around the time subjects respond48 or approximately 50 ms after the recorded response onset,53,82 and its topography is highly similar to the error-related negativity (ERN; Ne) for error but also correct responses,87–90 the fact that it is also present during the silent count condition strongly suggests that is it not contingent on a motor response. Still, FRN peak latencies during button presses, as identified in the grand mean CSD waveforms, were about 75 ms longer for patients compared to controls, thereby approximating but
