The Role of Reward and Inhibitory Systems in Subliminal and Supraliminal Processing of Facial Expression of Emotions- Brain Research Contribution

In comprehension of facial expression of emotions behavioural activation system (BAS) and behavioural inhibition system (BIS) was considered as an explicative factor to verify the effect of motivational/reward variable on cortical brain activity. Brain oscillation modulation, that is alpha band variation, was monitored within right- and left -cortical side when subjects consciously (supraliminal stimulation) or unconsciously (subliminal stimulation) processed facial patterns. The unconscious effect of an emotional stimulus was highlighted by a vast amount of research, whereas it remains questionable whether it is possible to assign a specific function to cortical oscillations in unconscious perception of facial expressions of emotions. Twenty subjects looked at six facial expressions of emotions (anger, fear, surprise, disgust, happiness, sadness, and neutral) in two different conditions: supraliminal (200 ms) vs subliminal (30 ms) stimulation (140 target-mask pairs for each condition). The results showed that both conscious and unconscious processing and significance of the stimulus can modulate the alpha power. Moreover, it was found an increased right frontal activity for negative, aversive emotions vs. an increased left response for positive emotion. Finally, whereas higher BIS subjects generated a more right hemisphere activation for negative emotions (mainly fear, anger, surprise, and disgust), BAS subjects were more responsive to positive emotion (happiness) within left hemisphere. Significance of facial expressions was adduced to elucidate cortical different responses to emotional types