A mismatch process in brief delayed matching-to-sample task: an fMRI study.

Our previous ERP studies have consistently demonstrated that a negativity N270 elicited by incongruent information in visual S1-S2 matching task represents a type of conflict process, which is distinct from that represented by the classic conflict task or other negative components in delayed matching-to-sample stimulus presentation patterns, since the inter-stimulus interval between S1 and S2 was presented as shorter as 500 ms. The N270 component of ERP was shown to reflect conflict processing during the simple working memory operations. In the present study, a functional MRI (fMRI) was used to investigate the visuospatial characteristics of brain activation associated with the task eliciting N270. The fMRI data showed an increased activation in the right anterior cingulate cortex (ACC, BA 24) and right dorsolateral prefrontal cortex (DLPFC, BA 46), and activation biased to the left occipitotemporal cortex (BA 37) in the incongruent condition. It is suggested that the greater activations of the right ACC coupling with right DLPFC to incongruent task reflect functional efficiency of the right cingulo-prefrontal network during the brief visual delayed period discrimination performance and mismatched information processing.