Subliminal and supraliminal processing of facial expression of emotions: brain oscillation in the left/right frontal area.

Michela Balconi,Chiara Ferrari

doi:10.3390/brainsci2020085

Abstract

The unconscious effects of an emotional stimulus have been highlighted by a vast amount of research, whereover it remains questionable whether it is possible to assign a specific function to cortical brain oscillations in the unconscious perception of facial expressions of emotions. Alpha band variation was monitored within the right- and left-cortical side when subjects consciously (supraliminal stimulation) or unconsciously (subliminal stimulation) processed facial patterns. Twenty subjects looked at six facial expressions of emotions (anger, fear, surprise, disgust, happiness, sadness, and neutral) under two different conditions: supraliminal (200 ms) vs. subliminal (30 ms) stimulation (140 target-mask pairs for each condition). The results showed that conscious/unconscious processing and the significance of the stimulus can modulate the alpha power. Moreover, it was found that there was an increased right frontal activity for negative emotions vs. an increased left response for positive emotion. The significance of facial expressions was adduced to elucidate cortical different responses to emotional types.

Highlights

IntroductionThe present paper intends to explore the left/right frontal brain oscillation modulation in response to different types of facial expression of emotions
Brain areas generally involved in evaluation of the emotional and motivational significance of facial expressions appear to be mediated by the amygdala and orbitofrontal cortex, while structures such as the anterior cingulate, prefrontal cortex and somatosensory areas are linked to conscious representation of emotional facial expression for strategic control of thought and action [2,3]
Left- and right-side activation was demonstrated in response to positive and negative faces respectively, even if it was mediated by the emotional significance of facial expressions in terms of their approach vs. avoidance attitude

Summary

Introduction

The present paper intends to explore the left/right frontal brain oscillation modulation in response to different types of facial expression of emotions. Faces are a critically important source of social information and it appears that we are biologically prepared to perceive and respond to faces in a unique manner [1]. Brain areas generally involved in evaluation of the emotional and motivational significance of facial expressions appear to be mediated by the amygdala and orbitofrontal cortex, while structures such as the anterior cingulate, prefrontal cortex and somatosensory areas are linked to conscious representation of emotional facial expression for strategic control of thought and action [2,3]. Considering the critical social relevance of emotional facial expressions, it is not surprising that the emotions displayed in facial expression can be perceived even when subjects have no conscious experience of perceiving them

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