Self and Other: An fMRI Study of Referential Processing and Retrieval

The self-reference effect has often been used as an indicator of how the brain processes information about ones self. Using fMRI, we studied the neural correlates of the self-reference effect during both encoding and retrieval by means of a unique paradigm of stimuli presentation. Changes in BOLD signal during self-referential processing were compared with those observed during mother-referential processing, and conjunction analysis of these two conditions resulted in joint activations of the superior fontal, inferior frontal and posterior cingulate gyri. Areas of the anterior cingulate gyrus and the visual word form area were observed for self-referential processing and not for mother-referential processing. During retrieval, hippocampal deactivation was observed for all memory tasks vs. the non-memory control task. Furthermore, the hippocampi deactivated less during the recall of self-referenced vs. mother-referenced items. Given that there was no significant difference between mean response times and recall accuracy between these conditions, the differences in deactivation are discussed as a way in which the recall of self-referenced material may be neurofunctionally special. Subjects in this study also performed a social attribution task in which they inferred mental states about geometric shapes. BOLD signal changes during this condition indicated activation of dorsomedial prefrontal cortices (DMPFC), bilateral ventral pathways including the fusiform face area, the amygdalae (right \u3e left), bilateral superior temporal sulci (STS, right \u3e left), anterior fusiform, and bilateral posterior cingulate gyri. In order to explore the areas of overlap between this more abstract social processing and the activations observed in the referential-processing task, an overlay map of these two tasks was created. Overlap was observed in the MPFC, the STS and posterior cingulate cortices. These findings are discussed in the context of a relationship between theory of mind and theory of self, and possible implications for the study of neuropsychiatric disorders are explored