Frontal midline theta and N200 amplitude reflect complementary information about expectancy and outcome evaluation


  • This study was supported by Natural Sciences and Engineering Research Council of Canada Discovery Grant RGPIN 312409-05. The authors would like to thank Dr. Olav Krigolson for making the data accessible for this research as well as Dr. Michael Masson and Dr. Michael Hunter for their guidance in implementing the statistical methods. The first author would also like to thank Dr. Josep Marco-Pallares for his invaluable influence on data analysis methods used in this research.

Address correspondence to: Azadeh HajiHosseini, Department of Psychology, P. O. Box 3050, University of Victoria, Victoria, BC, V8W 3P5 Canada. E-mail:


Feedback ERN (fERN) and frontal midline theta have both been proposed to index a dopamine-like reinforcement learning signal in anterior cingulate cortex (ACC). We investigated these proposals by comparing fERN amplitude and theta power with respect to their sensitivities to outcome valence and probability in a previously collected EEG dataset. Bayesian model comparison revealed a dissociation between the two measures, with fERN amplitude mainly sensitive to valence and theta power mainly sensitive to probability. Further, fERN amplitude was highly correlated with the portion of theta power that is consistent in phase across trials (i.e., evoked theta power). These results suggest that although both measures provide valuable information about cognitive function of frontal midline cortex, fERN amplitude is specifically sensitive to dopamine reinforcement learning signals whereas theta power reflects the ACC response to unexpected events.