Shaping the Visual Mismatch Response: The Influence of Exogenous Components and Stimulus Placement.

This study investigated the relationship between the pattern-specific event-related potential (ERP) components (C1, C2, C3) and the component specific to automatic change detection in the visual modality (visual mismatch response, vMMR) and the influence of stimulus placement on the latter. These insights would help to understand whether the emergence of vMMR is due to the modulation of exogenous activity or a specific deviant-related activity and advance the methodology of investigating vMMR. In two experiments, we presented checkerboard patterns in passive oddball sequences consisting of frequent (standard) and rare (deviant) events to examine vMMR as a function of the stimulated half-fields. In Experiment 1, the lower and upper half-field stimuli were presented within the same sequences, whereas in Experiment 2, they were presented in different sequences, completed with whole-field stimulation. As expected, we observed polarity reversal of the C1 and C2 components as a function of the stimulated half-field. Deviant stimuli elicited negative vMMR during lower and whole-field stimulation, but upper half-field stimulation evoked no significant vMMR. At lower half-field stimulation, the C2 component was larger to deviant stimuli, indicating the contribution of exogenous components to the deviant-standard difference. The sLORETA calculations showed that similar sources, including the primary visual cortex and other visual areas, were active during all exogenous and deviant-related components. Altogether, these results demonstrate the relationship between the pattern-specific and vMMR components and the more dominant influence of lower half-field stimulation in the recorded brain activity during automatic change detection.