Gamma-band neural synchrony due to autobiographical fact violation in a self-referential question.

Our purpose was to investigate the cortical information processing of autobiographical fact violation (AFV) in self-referential questions. We expected that AFV in a self-referential question would evoke a characteristic pattern of neural synchrony and event-related potentials (ERPs). Averaged ERP and event-related synchronization in the gamma band were analyzed to observe differences between the processing of questions with and without AFV. Significant differences in ERP were found in the posterior area at 290-435ms (N400) and in the frontal area at 520-800ms (late positive component, LPC). Interestingly, differentiation of the gamma-band synchrony was found in two temporal periods, (255-365 and 525-585ms), which are comparable to the periods of significant ERP differences. The two periods are interpreted to be devoted to the processing of semantic and self-referential information, respectively. These findings may imply that the decision-making involved in answering self-referential questions is enabled by the integration of semantic and autobiographical information processing.