Degrees of separation: a quantitative neuroimaging meta-analysis investigating self-specificity and shared neural activation between self- and other-reflection.

In functional neuroimaging studies, self-specificity has been investigated by contrasting other-relevant processing against the self. Our meta-analysis investigates self-specificity with respect to degrees of self-relatedness (SR) of the other (i.e. close and public other). Literature suggests a dorsal-ventral component of self- and other-reflection within the MPFC, which has yet to be analyzed according to varying SR, nor has it been quantified statistically. In the present meta-analysis, we pursued three main objectives. First, we conducted whole-brain ALE meta-analyses using contemporary literature analyzing self>close other and self>public other contrasts to determine self-specific regions sensitive to SR. Next, we conducted ALE and conjunction analyses of studies employing self>control, close other>control, or public other>control contrasts to determine shared regions of activation. Third, we conducted post hoc analyses to quantify any observed dorsal-ventral distinction, employing novel methodology using a surface-based coordinates system. We observed significant activation in the dACC and vACC for self>close other and self>public other, whereas anterior insula was observed only for self>public other. An MPFC dorsal-ventral distinction was observed and quantified whereby public other>control was significantly more dorsal than self>control and close other>control. Our results are discussed with regards to SR. Prospective avenues of research exploiting our methodology are proposed.