Studies in psychiatry and cognitive neuroscience have reported an important relationship between individual interoceptive accuracy and anxiety level. This indicates that greater attention to one's bodily state may contribute to the development of intense negative emotions and anxiety disorders. We hypothesized that reactivity in the anterior insular cortex underlies the intensity of interoceptive awareness and anxiety. To elucidate this triadic mechanism, we conducted functional magnetic resonance imaging (fMRI) and mediation analyses to examine the relationship between emotional disposition and activation in the anterior insular cortex while participants evaluated their own emotional and bodily states. Our results indicated that right anterior insular activation was positively correlated with individual levels of social anxiety and neuroticism and negatively correlated with agreeableness and extraversion. The results of the mediation analyses revealed that activity in the right anterior insula mediated the activity of neural correlates of interoceptive sensibility and social fear. Our findings suggest that attention to interoceptive sensation affects personality traits through how we feel emotion subjectively in various situations.

In this study, we investigated the neural substrate involved in the comprehension of novel metaphoric sentences by comparing the findings to those obtained with literal and anomalous sentences using event-related functional magnetic resonance imaging (fMRI). Stimuli consisted of 63 copula sentences ("An A is a B") in Japanese with metaphorical, literal, or anomalous meanings. Thirteen normal participants read these sentences silently and responded as to whether or not they could understand the meaning of each sentence. When participants read metaphoric sentences in contrast to literal sentences, higher activation was seen in the left medial frontal cortex (MeFC: Brodmann's area (BA) 9/10), the left superior frontal cortex (SFC: BA 9), and the left inferior frontal cortex (IFC: BA 45). The opposite contrast (literal sentences in contrast to metaphoric sentences) gave higher activation in the precuneus (BA 7) and the right middle and SFC (BA 8/9). These findings suggest that metaphor comprehension is involved in specific neural mechanisms of semantic and pragmatic processing which differ from those in literal comprehension. Especially, our results suggest that activation in the left IFC reflects the semantic processing and that activation in the MeFC reflects the process of inference for metaphorical interpretation to establish semantic coherence.