Good reputation enhances positive self-image, which motivates prosocial behavior, a phenomenon known as indirect reciprocity. Thus, good reputation should promote prosocial behavior toward estranged people to whom affective responses leading to direct reciprocity are suppressed. We predicted that such behaviors involve an interrelationship between self-image, processed in the medial prefrontal cortex (mPFC) and precuneus, and social reward, processed in the reward system. To test our hypothesis, we performed fMRI on 21 participants during a virtual ball-toss game after subjects formed negative impressions (estrangement) or neutral impressions of other players. During some blocks of the game, the other players did not receive tosses, and participants could increase tosses to them (i.e. engage in prosocial behavior). Participants significantly increased tosses to all isolated players; therefore, prosocial behavior occurred irrespective of estrangement. Prosocial behavior toward estranged players enhanced positive self-image and increased activation of the anterior mPFC and precuneus. The precuneus exhibited enhanced functional connectivity with the striatum. Thus, a positive self-image, represented by an interaction between the midline cortical structures and striatum, plays key roles in prosocial behavior toward estranged people.

良好的声誉可以增强积极的自我形象，从而激发亲社会行为，这种现象被称为间接互惠。因此，良好的声誉应促进对疏远者的亲社会行为，因为他们对导致直接互惠的情感反应受到抑制。我们预测，这种行为涉及在内侧前额叶皮层（mPFC）和早孕中处理的自我形象与在奖励系统中处理的社会奖励之间的相互关系。为了检验我们的假设，在受试者进行负面印象（疏远）或其他玩家的中立印象之后，我们在虚拟的掷球游戏中对21名参与者进行了功能磁共振成像。在游戏的某些阶段中，其他玩家没有得到掷骰子，参与者可以增加对他们的掷骰子（即参与亲社会行为）。参与者大大增加了对所有孤立玩家的投掷；因此，不论是否疏远，都会发生亲社会行为。对疏远的玩家的亲社会行为增强了积极的自我形象，并增强了前mPFC和足前突的激活。前胎表现出与纹状体增强的功能连通性。因此，以中线皮层结构和纹状体之间的相互作用为代表的积极的自我形象在对疏远人群的亲社会行为中起着关键作用。