Laterality, EEG alpha band power and behavioural inhibition (BIS) and activation (BAS) systems in emotional face comprehension

Objective: Brain asymmetry in response to emotional facial expressions is a main topic in emotion domain. Brain oscillations was used to analyze the contribution of cortical rhythms in this process. Secondly, behavioural activation system (BAS) and behavioural inhibition system (BIS) were considered such as an explicative factor for measuring the effect of motivational/emotional variable on alpha activity within the two hemispheres. Third, valence and arousal were considered as explicative factors in elucidating emotional face comprehension. Participants and Methods: Asimmetry in comprehending facial expression of emotions was explored in the present research by analyzing EEG alpha frequency band variations within right- and left-cortical side. Nineteen subjects were submitted to an ample range of emotional facial expressions (anger, fear, surprise, disgust, happiness, sadness, and neutral). Results: The results demonstrated that anterior frontal sites were more active (alpha decreasing) than central and parietal sites in response to facial stimuli. Moreover, right and left side responses varied as a function of emotional types, with an increased right frontal activity for negative emotions vs. an increased left response for positive emotion. Finally, whereas higher BIS subjects generated a more right hemisphere activation for negative, high arousing emotions (such as fear, anger, and disgust), BAS subjects were more responsive to positive emotion (happiness) within left hemisphere. Conclusions: Valence and arousing power of facial expressions were considered to elucidate cortical differences in subjects’ responses to emotional types, in addition to BIS/BAS system.