Brain regional networks active during the mismatch negativity vary with paradigm

We used independent component analysis (ICA) of high-density EEG recordings coupled with single dipole fitting to identify the dominant brain regions active during the MMN in two different versions of a passive oddball paradigm: a simple, monotic, frequency-deviant paradigm and a more complex, dichotic, frequency-deviant paradigm with deviants occurring in either ear alone or in both ears at the same time. In both paradigms we found brain regional sources in the temporal and frontal cortices active during the MMN period, consistent with some previous studies. In the simpler paradigm, the scalp-potential variance during the earlier (70-120 ms) MMN was mostly accounted for by a wide array of temporal, frontal, and parietal sources. In the more complex paradigm, however, a generator in the prefrontal cortex accounted for a substantial amount of the variance of the scalp potential during the somewhat later MMN period (120-200 ms). These findings are consistent with a more nuanced view of the MMN and its generators than has been held in the past.