Discrimination of social reward inequalities in rats

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K22475
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 46:Neuroscience and related fields
• Research Institution: Jichi Medical University
• Principal Investigator: Onaka Tatsushi 自治医科大学, 医学部, 教授 (90177254)
• Project Period (FY): 2019-06-28 – 2023-03-31
• Keywords: 愛着様行動 / 羨望

Outline of Final Research Achievements

After receiving stroking stimuli repetitively from an early age, rats exhibit pet-like behaviors, such as distinguishing and following the human who have petted them. Using this animal model, we examined whether rats can discriminate inequality in social rewards. In this model, interaction with a familiar experimenter was used as a social reward. In the present study, rats received repeated stroking stimuli after weaning. In a social inequality condition, only other individuals received stroking stimuli in front of them. Rats emitted a special type of ultrasonic vocalizations in this situation while rats emitted 50 kHz calls, indicative of the appetitive state, with an affiliative human in front of them. All these data suggest that rats could discriminate social inequality conditions. Experiments with an oxytocin receptor antagonist suggested that the oxytocin receptor is not essential for expression of affiliative behaviors.

Free Research Field

生理学

Academic Significance and Societal Importance of the Research Achievements

不平等を嫌う感情や特定の相手との排他的関係を求める嫉妬感情は社会的規範・道徳性の起源に繋がる感情と考えられ、社会を構築するのに基盤的な社会的情動である。しかし、羨望・嫉妬の感情がどの程度生得的で生物学的基盤をもつものなのか、あるいは、社会的文化的に形成されるものかは分かっていなかった。本研究により集団生活を行う齧歯動物において社会的報酬の不平等を識別することが明らかとなり、その生物学的基盤を探求する道が開けた。