2013年12月11日水曜日

Right supramarginal gyrus is crucial to overcome emotional egocentricity bias in social judgments

Giorgia Silani, Claus Lamm, Christian C Ruff, and Tania Singer
The Journal of Neuroscience, 25 September 2013, 33(39): 15466-15476

ヒト、行動+fMRI+rTMS実験。
ヒトは「自分の感情を投影して他者の感情を判断する」クセがある。
そして、そのクセは縁上回(Supramarginal Gyrus)が活動しているときに抑えられる。
実際、rTMSで縁上回の活動を一時的に抑制してやると、「自分の感情を投影して他者の感情を判断するクセ」が強くなった。

Humans tend to use the self as a reference point to perceive the world and gain information about other people's mental states. However, applying such a self-referential projection mechanism in situations where it is inappropriate can result in egocentrically biased judgments. To assess egocentricity bias in the emotional domain (EEB), we developed a novel visuo-tactile paradigm assessing the degree to which empathic judgments are biased by one's own emotions if they are incongruent to those of the person we empathize with. A first behavioral experiment confirmed the existence of such EEB, and two independent fMRI experiments revealed that overcoming biased empathic judgments is associated with increased activation in the right supramarginal gyrus (rSMG), in a location distinct from activations in right temporoparietal junction reported in previous social cognition studies. Using temporary disruption of rSMG with repetitive transcranial magnetic stimulation resulted in a substantial increase of EEB, and so did reducing visuo-tactile stimulation time as shown in an additional behavioral experiment. Our findings provide converging evidence from multiple methods and experiments that rSMG is crucial for overcoming emotional egocentricity. Effective connectivity analyses suggest that this may be achieved by early perceptual regulation processes disambiguating proprioceptive first-person information (touch) from exteroceptive third-person information (vision) during incongruency between self- and other-related affective states. Our study extends previous models of social cognition. It shows that although shared neural networks may underlie emotional understanding in some situations, an additional mechanism subserved by rSMG is needed to avoid biased social judgments in other situations.

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