Effects of Mood Induction on Frontal Asymmetry in Individuals with Behavioral Activation/Inhibition Systems

Aim and The behavioral inhibition system (BIS) and the behavioral activation system (BAS) are considered as factors to verify the effects of personality significance on cortical activity. The present study explored the effects of the BIS and BAS on frontal asymmetry in response to affect stimuli. Methods and Materials: This study included 36 individuals (18 with high BAS sensitivity and 18 with high BIS sensitivity، 17 women). All subjects were introduced to neutral، happy، and sad conditions by the International Affective Pictures System (IAPS) and brain waves were recorded simultaneously. Finally، absolute power of alpha band (8-12 Hz) of the right and left frontal areas were calculated for each participant. A mixed repeated measurements analysis of variance (ANOVA) was used to analyze the absolute alpha power. Results revealed an increased response to neutral stimuli in BAS group within the left frontal area. However، no significant effects were found in the BIS group in this condition. In addition، an increased left frontal activity (alpha decreasing) in response to happy pictures was seen in the BAS group. On the other hand، an increased right frontal activity (alpha decreasing) in response to sad pictures was found in the BIS group. The results were consistent with the approach/withdrawal model and cerebral asymmetry. The role of the frontal region in positive and negative moods was also approved.