Abstract
Growing evidence shows that the posterior region of superior temporal sulcus (pSTS) is engaged in emotional processing, especially during cross-modal integration. However, most of these studies used Caucasian participants and Western-based stimuli. Critically, studies have demonstrated that a person’s cultural background modulates the manner of how facial expressions are processed. Here, we examined the neural mechanisms underlying the processing of East Asian facial expressions and elucidated the role of pSTS in the visual modality using contrast analyses and dynamic causal modeling (DCM) of fMRI responses. Facial expressions of different identities portraying the six basic emotions, including anger, disgust, fear, happiness, sadness, and surprise, were contrasted with those portraying neutral expression. At the beginning of each block, an affective label in Chinese was displayed followed by 8 sequentially presented faces from the same emotional category. Participants judged the emotional intensity of each facial expression. The results showed significant neural activation in the pSTS across all emotional contrasts, especially in the right hemisphere, except for the facial expression of happiness. This finding suggests the pSTS plays a general, rather than cultural specific, role in emotional processing. Only disgusted expressions showed activation in the middle and anterior cingulate cortex, and only surprised expressions activated the amygdala, a widely regarded hub for emotional processing in the brain. DCM indicated that (a) the fusiform gyrus (FFG) and pSTS in the two hemispheres were interconnected, and (b) the projection between bilateral FFG and amygdala were modulated by bilateral pSTS. These results partially confirm Müller et al.’s (2012, Neuroimage) findings, and suggest a critical role for pSTS in emotional processing even in the processing of emotion conveyed in a single visual modality via faces.
Acknowledgement: The study reported here was supported by the Ministry of Science and Technology, Taiwan (No.: 107-2420-H-194-006)