2012年11月7日水曜日

The Emergence and Representation of Knowledge about Social and Nonsocial Hierarchies


Dharshan Kumaran, Hans Ludwig Melo, Emrah Duzel
Neuron, Volume 76, Issue 3, 653-666, 8 November 2012

「社会的階層の学習」と扁桃体。扁桃体の活動と学習の進み具合が相関する。また、学習成績の個人差は扁桃体の大きさで説明できる。一方、海馬は社会的階層に限らず「一般的な順位の学習」に関与する。 http://www.cell.com/neuron/abstract/S0896-6273(12)00889-6

Primates are remarkably adept at ranking each other within social hierarchies, a capacity that is critical to successful group living. Surprisingly little, however, is understood about the neurobiology underlying this quintessential aspect of primate cognition. In our experiment, participants first acquired knowledge about a social and a nonsocial hierarchy and then used this information to guide investment decisions. We found that neural activity in the amygdala tracked the development of knowledge about a social, but not a nonsocial, hierarchy. Further, structural variations in amygdala gray matter volume accounted for interindividual differences in social transitivity performance. Finally, the amygdala expressed a neural signal selectively coding for social rank, whose robustness predicted the influence of rank on participants’ investment decisions. In contrast, we observed that the linear structure of both social and nonsocial hierarchies was represented at a neural level in the hippocampus. Our study implicates the amygdala in the emergence and representation of knowledge about social hierarchies and distinguishes the domain-general contribution of the hippocampus.

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