Biological Computation Indexes of Brain Oscillations in Unattended Facial Expression Processing Based on Event-Related Synchronization/Desynchronization

The automatic detection of unexpected emotion and neutral body postures: A visual mismatch negativity study

The ability to automatically detect emotional changes in the environment is crucial for social interaction. In the visual system, expression-related mismatch negativity (EMMN) reflects the automatic processing of emotional changes in facial expression. However, body postures also carry visual emotional information that can be recognized effectively and processed automatically, although their processing mechanism remains unknown. In this study, the reverse oddball paradigm was used to investigate the mismatch responses of unexpected fear and neutral body postures. The nonparametric cluster permutation test revealed significant fear and neutral visual mismatch negativity (vMMN) activities, and the fear-related vMMN was enhanced prior (130-230 ms) to the neutral vMMN (180-230 ms). The body-sensitive N190 component may partially account for the vMMN obtained in this study. The fearful body posture evoked a greater N190 response over the neutral body, and amplitudes of N190 were more negative in the deviant condition than the standard condition. Additionally, the body-related visual mismatch oscillatory responses were associated with enhancement of the alpha band oscillation, especially for the fearful body posture. These results expanded the applicable scope of body posture cues corresponding to mismatch signals, objectively defined the electrophysiological activities evoked, and revealed the processing bias toward negative emotion.

Consciousness modulates the automatic change detection of masked emotional faces: Evidence from visual mismatch negativity

The ability to automatically detect changes in the environment is crucial for organisms to survive. In the visual system, changes in visual stimuli may evoke visual mismatch negativity (vMMN), an event-related potential (ERP) component that reflects automatic change detection. Previous studies that used visual masking to examine the effects of consciousness did not yield evidence that vMMN could be elicited by subliminal stimuli. However, these studies used relatively simple visual features. To further examine the role of consciousness in vMMN, the present study used emotional (happy and fearful) faces, which are biologically and socially significant visual stimuli. A passive oddball paradigm was employed, and we found that only fearful faces could evoke vMMN at a low consciousness level. Furthermore, the fear-related vMMN was enhanced by the consciousness level, and localized in regions of the brain associated with emotional face processing and the prefrontal cortex. We also found that the emotional visual mismatch oscillatory responses (vMORs) were associated with the enhancement of the alpha-band oscillation. Moreover, consciousness could weaken the happiness-related vMOR. These results suggested that changes to emotional faces-especially fearful faces-could be unconsciously detected by the brain. More importantly, this automatic change detection mechanism could be modulated by consciousness.