Theta power as a marker for cognitive interference

Objective: The present study aimed at investigating whether theta activity within medio-frontal cortex (MFC) serves as a marker for increased cognitive control demands such as performance monitoring. Methods: We confronted participants with at least two incompatible sources of information in a Simon task, a flanker task, and a NoGo task to assess whether changes in EEG theta activity correspond to executive control demands across different sources of cognitive interference. Results: Overall, increases of theta power were to a different extent observed in all interference situations: (1) differences in theta power were largest between successful response inhibition in NoGo events compared to Go responses, (2) incongruent and congruent events in the flanker task differed to a lesser extent, and (3) differences in theta power were smallest comparing incompatible and compatible Simon events. Scalp-topographies and dipole modeling of theta activity pointed to different sources across interference conditions that encompassed various MFC areas within anterior cingulate cortex and (pre-) supplementary motor areas. Conclusions: Our results indicate that theta power amplitude is sensitive to the recruitment of executive control in interference situations, whereas the MFC sources of theta power varied across different interference situations. Significance: This study shows for the first time theta power enhancement related to the recruitment of cognitive control across different types of conflicts in the stream of information processing. (C) 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.