关键词: 公平, 最后通牒任务, 功能磁共振成像, 腹内侧前额叶, 脑岛

Abstract: Given that we live in highly complex social environments, many of important decisions are made in the context of social interactions. A lot of studies have found that people are willing to sacrifice their own interests to maintain fair, which is called inequity aversion tendency. Simple but sophisticated tasks kown as UG（Ultimatum Game）have been used to study fairness in the laboratory setting , UG is a useful experimental tool for examining both decisions about, and responses to, fairness and equity . The Ultimatum Game (UG) is often used to examine responses to fairness. In the UG, two players must divide a sum of money, with the proposer specifying the division. The responder then has the option of accepting or rejecting this offer. If the offer is accepted, the sum is divided as proposed. If it is rejected, neither player receives anything. The UG therefore models decisions about resource allocation on the part of the proposer, as well as responses to fairness and inequity in the responder. The proposer’s decision is based on the degree of activation of VMPFC. VMPFC patients show “negative generosity” by offering less than they themselves demand，VMPFC is thought to be responsible for emotional processing and empathy，VMPFC patients can not understand unfair allocation will be rejected by responders. Moreover, unfair offers that were subsequently rejected were associated with a stronger insula response than those that were subsequently accepted, suggesting that the magnitude of anterior insula activation in?uences the decision to accept or reject. For different roles, the fairness behavior have different mechanism. For example, testosterone have different effects on different roles .It may have an similar effect on VMPFC function for proposers, Testosterone can increase individuals’ "negative generosity” behavior. On the other side, it also contributes to the individual refusal behavior for unfair distribution. In addition, a variety of neuroscience methods have been used to probe the underlying neural systems of fairness. This review highlights neural mechanisms of fairness, and describes existing theoretical models in detail. Although differences have been found in proposer and responder’s behavior, the fairness have some common basis. Brain imaging studies have found that the fairness was associated with activation in a network of regions including the insula which is responsible for the emotional processing and the dorsal medial prefrontal cortex which is responsible for cognitive control. As kind of neuromodulators, Oxytocin plays a catalytic role in social altruism behaviors such as fairness. It has been verified by many previous studies. This review point out some problems and the future research direction for the neural mechanisms of fairness.

Key words: fairness, Ultimatum Game, fMRI, VMPFC, insula