Oscillatory activity in theta (∼4–7 Hz) range in human electroencephalographic (EEG) recordings during cognitive tasks is maximal over fronto-midline scalp regions and has been termed fm-theta [1], [2]. Increased fm-theta power is associated with engagement of executive functions during cognitive inhibition [3], [4], [5] and in response to higher working memory load [6], [7], and errors [8]. Human intracranial studies indicate that fm-theta oscillations are generated in the anterior cingulate cortex (ACC) [9], [10], [11], confirming source modeling of scalp EEG sources to ACC or surrounding medial prefrontal cortex [12], [13], [14], [15]. However, because of their low spatial resolution, EEG estimates may be insensitive to other local theta generators such as the frontal and parietal cortices, revealed by intracranial recordings [11], [16], [17]. Indeed, extensive fMRI-based evidence indicates that various executive tasks activate an overlapping network including medial and lateral prefrontal and lateral parietal cortices [18], [19], [20], [21]. ACC, also termed rostral cingulate zone [22], seems to be the nexus of this distributed network and is particularly activated by conflict-inducing conditions that rely on controlled processing [23], [24], [25].
