Gender differences in neural correlates of recognition of happy and sad faces in humans assessed by functional magnetic resonance imaging

To examine the effect of gender on the volume and pattern of brain activation during the viewing of alternating sets of faces depicting happy or sad expressions, 24 volunteers, 12 men and 12 women, participated in this functional magnetic resonance imaging study. The experimental stimuli were 12 photographs of Japanese adults selected from Matsumoto and Ekman's Pictures of Facial Affect. Four of these pictures depicted happy facial emotions, four sad, and four neutral. Half of the photographs were of men and the other half were of women. Consistent with previous findings, distinct sets of neural correlates for processing happy and sad facial emotions were noted. Furthermore, it was observed that male and female subjects used a rather different set of neural correlates when processing faces showing either happy or sad expressions. This was more noticeable when they were processing faces portraying sad emotions than happy emotions. Our findings provide some preliminary support for the speculation that the two genders may be associated with different areas of brain activation during emotion recognition of happy or sad facial expressions. This suggests that the generalizability of findings in regard to neural correlates of facial emotion recognition should consider the gender of the subjects.