A Monitoring Brain System for the Evaluation of Information

This study explored brain electrical activity and generators related to error detection and violation of expectation, using electroencephalogram (EEG) activity from 128 scalp sites. In addition to classical ERP analyses, we applied frequency (wavelet) analyses and sLORETA source localization. Our main aims were: to look for the existence of a general monitoring system that evaluates information; to test the relation between the monitoring system and the anterior cingulate cortex (ACC) and its theta electro-physiological rhythm; to test whether the activity of this monitoring system could be triggered unintentionally; and to test the sensitivity of this system to the degree of deviation from the expected values. Results indicated that evaluating the correctness of arithmetical equations is related to medial-frontal phase-locked theta activity, power, and synchrony. Source localization suggested the ACC is a main brain generator involved in these theta effects. These effects depended nonlinearly on the degree of deviation from the expected information. In the case of arithmetical violations, fronto-medial activity was preceded by activity over right parietal areas. Our study also indicated that linguistic violations, such as semantic violations and spelling errors, elicit similar theta effects. Moreover, we demonstrated that these brain responses can also be elicited unintentionally and can be separated from the brain response to conflict, for example, an incongruent Stroop condition. We also found age and gender effects in the brain response to violations of expectations. Lastly, there were also individual differences in these responses, which were quite stable and related to temperamental differences in effortful control.