DOI: 10.5176/2251-1865_CBP39
Authors: Tetsuya Iidaka
Abstract: Emotional concern for another person is a critical mental function associated with social communication and interpersonal relationships. In particular, emotion is influenced by the facial expressions of another person, a phenomenon referred to as “emotional contagion”; however, its neural correlates are not fully understood. Several neuroimaging studies have shown that the neural circuit involving the superior temporal sulcus (STS), amygdala, and prefrontal cortex (PFC) plays a key role in understanding facial expressions. Clinical studies have indicated that the functioning of this neural circuit is impaired in patients with autism spectrum disorder (ASD) and schizophrenia. In these patients, blunted affect and indifference to facial expression are frequently observed as clinical symptoms. On the other hand, neurophysiological studies in monkeys indicate that the mirror neuron system in the STS, temporoparietal junction, and PFC are activated when the subject views the motor activities of another monkey. In the present study, we aimed to elucidate the neuroanatomical substrates of emotional contagion by using functional magnetic resonance imaging of normal human subjects. The subjects (n = 9, mean age: 23 years) were scanned while observing a dynamic movie of a happy expression, a static picture of the same person with a neutral expression (target face), and a static picture of another person with a neutral expression (non-target face). The subject’s brain response was measured using a 3 Tesla MRI scanner in an event-related manner. After the scan, the subjects rated how their emotion was influenced by viewing the dynamic expression video using a 7-point Likert scale. The functional imaging data was analyzed using SPM8 software and a random effects model. Subtraction analysis comparing the brain’s response to the target face and its response to the non-target face revealed activation in the PFC and STS regions. These regions were involved in assuming the other person’s emotional state from the neutral face. In addition, the subjective rating of the subject’s own emotional state significantly and positively correlated with neural activity in the left medial PFC (r = 0.89, p < 0.01). This indicated that the subjects who were influenced by another’s emotion tended to show large activation in the medial PFC. These preliminary results suggest that a part of the PFC may be the neural correlate of emotional contagion by another person’s facial expression. Future studies using patient groups may elucidate dysfunction of emotional empathy in ASD and schizophrenia.
Keywords: emotion; empathy; mirror neuron; fMRI; face
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