Gender differences in neural activity associated with recognition of happy and sad faces by human subjects: An functional magnetic resonance imaging study

Abstract

Do men and women process emotional stimuli differently? This question has been addressed in some prior studies. For example, Kesler/West et al. [1] used functional magnetic resonance imaging (fMRI) to investigate explicit processing of facial emotions, including happiness and sadness. They observed that men showed greater left hemispheric activation when observing sad faces than when observing happy faces. This study explored how the gender of the subjects and of the stimuli affects neural activity associated with emotion recognition of happy or sad expressions using a functional magnetic resonance imaging. The experimental stimuli were 12 photographs of Japanese adults selected from Matsumoto and Ekman’s Pictures of Facial Affect. Using a blocked-design paradigm, the neural activity of the 24 volunteers, 12 men and 12 women, was monitored on a 1.5 T Magnetom Vision MRI scanner (Siemens, Erlangen, Germany) at the Chang Gung Memorial Hospital while they were viewing photos of men or women portraying happy or sad emotions shown through a goggle display system (Resonance Technology Inc., Calif., USA). Our findings support previous reports of gender differences in the neural correlates of emotion recognition, which seems to relate to both the gender of the subjects and the gender of the models portraying the target facial emotions. Our observation of a stronger activation associated with facial emotion recognition in our male subjects, particularly when viewing sad facial emotions, is consistent with our previous finding [2]that gender differences in facial emotion recognition are more noticeable when processing faces portraying sad emotions than when processing faces portraying happy emotions. Relative differences were observed between the male and female subjects in the volume of activation and the lateralization pattern associated with processing emotion recognition when looking at male or female faces. Regarding regions and volumes of activation, both our male and female subjects, when viewing happy emotions portrayed by models of the same gender as themselves, displayed a stronger and a more extensive network of activation. In terms of the lateralization pattern, we observed a general trend of their becoming less left lateralized when our male or female subjects were viewing photos of women portraying either happy or sad emotions than when they were viewing photos of men. Our findings suggest that the laterality of facial emotion processing could be gender, subjects and stimuli, and emotion specific. This observation may further explain the contradictory findings of laterality models of emotion processing reported in the literature. Our findings suggest fundamental gender differences in neural activity associated with processing emotion in male or female faces. Thus, the generalization of the findings in regard to neural activity associated with facial emotion recognition should take gender of the subjects as well as the stimuli into the consideration. References 1 Kesler-West M, et al: Cogn Brain Res 2001; 11: 213–226. 2 Lee TMC, et al: Neurosci Lett 2002; 333: 13–16.