抄録
The prefrontal cortex can be divided into two parts, the lateral and medial, traditionally held to have dissociable functions. In the present talk, we demonstrate the functional dissociation of medial and lateral prefrontal regions that contribute to behavioral flexibility along cognitive-emotional axis. Decomposition of brain activity measured by fMRI revealed dissociation of three groups of prefrontal regions and related mental components involved in set shifting required during performance of the Wisconsin Card Sorting Test (WCST): the left lateral region associated with update of behavioral set, the right lateral region associated with inference of the meaning of negative feedback, and the medial region associated with emotion evoked by the presentation of negative feedback. The medial region was segregated from the pre-supplementary motor area activated during set shifting and from the anterior cingulate regions known to be associated with conflict monitoring and error detection. The medial region was also reproducibly activated during presentation of negative feedback in a motion prediction task, a situation simpler than the WCST. Furthermore, the medial prefrontal activity in the prediction task correlated with emotional aspects of personality traits of individual subjects as indexed by psychological assessments. These results suggest that traditional cognitive-emotional dichotomy of the lateral and medial prefrontal functions holds during set shifting, and that the medial prefrontal cortex is functionally heterogeneous, as has been widely accepted regarding the lateral prefrontal cortex. [J Physiol Sci. 2007;57 Suppl:S25]
