Frontal brain oscillation modulation in facial emotion comprehension: The role of reward and inhibitory systems in subliminal and supraliminal processing

Abstract

Brain oscillation modulation in comprehension of facial expression of emotions was explored in the present study. Second, behavioural activation system (BAS) and behavioural inhibition system (BIS) was considered to verify the effect of motivational/emotional variable on alpha activity. In addition, alpha band variation was monitored when subjects attentively (supraliminal) or preattentively (subliminal) processed faces. In fact, it remains an open question whether it is possible to assign a specific function to cortical oscillations for facial emotion comprehension in unconscious perception. Eighteen participants looked at an ample range of facial expressions of emotions (anger, fear, surprise, disgust, happiness, sadness, neutral) in two different conditions: supraliminal and subliminal stimulation. The results showed that both attentive and preattentive processing can modulate the alpha power. Moreover, frontal right and left side responses varied as a function of emotional types, with increased right frontal activity for negative, aversive emotions versus an increased left response for positive emotion. Finally, higher scoring BIS participants generated more right hemisphere activation for some negative emotions, whereas higher scoring BAS participants were more responsive to a positive emotion measured over the left hemisphere. Motivational significance of facial expressions was considered to elucidate cortical differences in participants’ responses to emotional types.

Keywords:

• Alpha power
• Emotion
• Facial expression
• Frequency band analysis
• Hemispheric differences

Acknowledgements

This study was supported by grant from the National Research Foundation (D.1./2010) of the Catholic University of Milan.