Abstract
Orientation is one of the important elements of objects that can influence visual processing. In this study, we examined whether changes in orientation could be detected automatically under unattended condition. Visual mismatch negativity (vMMN) was used to analyze this processing. In addition, we investigated the underlying neural oscillatory activity. Non-phase-locked spectral power was used to explore the specific frequency related to unexpected changes in orientation. The experiment consisted of standard (0° arrows) and deviant (90°/270° arrows) stimuli. Compared with standard stimuli, deviant stimuli elicited a larger N170 component (negative wave approximately 170 ms after the stimuli started) and a smaller P2 component (positive wave approximately 200 ms after the stimuli started). Furthermore, vMMN was obtained by subtracting the event-related potential (ERP) waveforms in response to standard stimuli from those elicited in response to deviant stimuli. According to the time–frequency analysis, deviant stimuli elicited enhanced band power compared with standard stimuli in the delta and theta bands. Compared with previous studies, we concluded that theta activity plays an important role in the generation of the vMMN induced by changes in orientation.
Highlights
IntroductionDetecting orientation changes can be vital to survival, especially under unattended condition
We focused on the cardinal orientations and sought to investigate the role of neural oscillations in the Visual MMN (vMMN) response
The results showed that accuracy was more than 93.5%, which means our event-related potential (ERP) and EEG data were recorded under unattended condition
Summary
Detecting orientation changes can be vital to survival, especially under unattended condition. This process can be studied using a component of eventrelated potential (ERP) called mismatch negativity (MMN). MMN is a reliable indicator of change-detection processing (Näätänen et al, 2007; Fuentemilla et al, 2008). Visual MMN (vMMN) can be elicited by visual oddball tasks (20% deviant stimuli are inserted randomly in a sequence of 80% standard stimuli). Researchers found that the lateral N1b subcomponent (120–200 ms) and P2 component (200–300 ms) were related to vMMN (Czigler et al, 2006; Hietanen et al, 2008).
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