Crows, a highly social bird, live in a complex 'fission-fusion' society where individuals need to recognize identity of group members with forming social relationships such as dominance. Such social nature could predict the existence of the integrative brain mechanisms for individual recognition and dominance relationships. Despite a number of evidence for the sophisticated cognitive abilities of this species, little has been unknown on the neural basis for social cognition. In this study, to clarify how to integrate individual recognition, dominance, and behavioral expression, we investigated pallial-limbic system including association pallium, striatum, and hypothalamus by analyzing expression of immediate early gene ZENK, an indirect neuronal activity marker. Firstly, the formation of stable dominance relationships based on the individual recognition was confirmed between male jungle crows in a dyadic encounter paradigm. Then the neuronal activities during an exposure session where each subject crow was exposed to either of a familiar dominant, subordinate, or an unfamiliar 'stuff' crow as a stimulus. To evaluate the multiple contributions of each brain area to cognitive/behavioral aspects, ZENK expression was analyzed by means of a generalized regression model (GdML) base on multi-ple factors such as familiarity, dominance, and non-specific actions of the stimulus crow. Neuronal correlation to familiarity was found mainly in association pallium, whereas that to aggression was found in sub-pallial areas. Hippocampal complex and septal nuclei, furthermore, showed multiple contribution to the factors. Given those results together with the past anatomical studies, we could propose a hypothetical neural system, 'association pallium – parahippocampal – septal subdivisions,' for dominance recognition.
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