Cross-frequency dynamics of neuromagnetic oscillatory activity: two mechanisms of emotion regulation.

Hemodynamic and electromagnetic neuroimaging suggests a sequence of intraregional and interregional activity during emotion processing. Oscillatory activity within trials may offer insight into neural mechanisms involved in this process. MEG was measured in 24 subjects during passive viewing of neutral and unpleasant pictures and emotion regulation by cognitive reappraisal. Regulation prompted more gamma increase and alpha decrease to picture onset than did passive viewing. Source analysis confirmed differential modulation of these power changes in occipitoparietal regions during passive viewing and larger power changes in prefrontal regions during regulation. Local coupling of alpha phase to gamma amplitude within a medial prefrontal region and long-range synchrony of medial prefrontal, occipital, and temporoparietal regions index mechanisms of prefrontal top-down contribution to emotion processing.