Source localization of event-related potentials related to cross-modal semantic interference effect using scalp-skull-brain dipole tracing method

The object of this study was to investigate the source localization of event-related potentials (ERPs) related to cross-modal semantic interference effect. Twenty-eight healthy volunteers participated in the study, in which ERPs were measured while subjects judged the semantic relationship between a test picture and a preceding context picture where a superimposed context word was either semantically related (related condition) or unrelated (unrelated condition) to the test picture. The source localization of the equivalent current dipoles (ECDs) of the ERP components, which significantly varied between the related and the unrelated condition when the pictures were semantically unrelated, was determined by the scalp-skull-brain dipole tracing (SSB-DT) method using a two-dipole model. Three distinct components were observed in the difference ERPs obtained by subtracting the ERPs of the unrelated condition from those of the related condition: An early positive component arising in the latency range of 380-420 ms, a negative component in the latency range of 520560 ms, and a late positive component in the latency range of 680-720 ms. According to the SSB-DT method, significant ECDs were found only for the negative component. The ECDs of the negative component were localized in the night anterior cingulate gyrus and the left superior temporal gyrus, which was nearly in accordance with the source generator of the response conflict negativity reported in previous studies.