2009 年 7 巻 2 号 p. 129-135
Theory of Mind (ToM) which the ability to attribute mental states to others are important processes in social cognition. Brain imaging studies in healthy subjects have described a brain system involving medial prefrontal cortex, superior temporal sulcus and temporal pole in ToM processing. In this functional magnetic resonance imaging (fMRI) study, we used the picture sequencing tasks with both intentional story (ToM story) and physical story in order to allow comparison of brain activations in these two processes. Participants were ten right-handed healthy Japanese volunteers (male = 5, female = 5; mean age was 24.9 years, s.d. = 1.4). Functional images were acquired using a 1.5 T Siemens Magnetom Vision. Our results showed that the ToM story compared to the physical story revealed increased activations in bilateral superior frontal gyrus, medial frontal gyrus, and right middle frontal gyrus. Correct responses in the ToM story were associated with enhanced activations of right middle frontal gyrus, bilateral superior frontal gyrus, right orbital gyrus, and left inferior frontal gyrus. These activations are common to a part of results in previous brain imaging studies on ToM and social cognitive functions using various tasks. The present study suggests that social cognition in a nonverbal task is especially associated with the medial and right middle frontal function. These results have implications for our understanding of disorders characterized by impairments of social cognition which are related to making references about mental states of others, such as schizophrenia and autism.