Department of Psychology, Centre for Studies and Research in Cognitive Neuroscience, University of Bologna Cesena, FC, Italy.
Front Hum Neurosci. 2013 Sep 25;7:593. doi: 10.3389/fnhum.2013.00593. eCollection 2013.
Although trust and reciprocity are ubiquitous in social exchange, their neurobiological substrate remains largely unknown. Here, we investigated the effect of damage to the ventromedial prefrontal cortex (vmPFC)-a brain region critical for valuing social information-on individuals' decisions in a trust game and in a risk game. In the trust game, one player, the investor, is endowed with a sum of money, which she can keep or invest. The amount she decides to invest is tripled and sent to the other player, the trustee, who then decides what fraction to return to the investor. In separate runs, ten patients with focal bilateral damage to the vmPFC and control participants made decision while playing in the role of either investor or trustee with different anonymous counterparts in each run. A risk game was also included in which the investor faced exactly the same decisions as in the trust game, but a random device (i.e., a computer), not another player, determined the final payoffs. Results showed that vmPFC patients' investments were not modulated by the type of opponent player (e.g., human vs. computer) present in the environment. Thus, vmPFC patients showed comparable risk-taking preferences both in social (trust game) and nonsocial (risk game) contexts. In stark contrast, control participants were less willing to take risk and invest when they believed that they were interacting with people than a computer. Furthermore, when acted as trustee, vmPFC patients made lower back transfers toward investors, thereby showing less reciprocity behavior. Taken together, these results indicate that social valuation and emotion subserved by vmPFC have a critical role in trusting and reciprocity decisions. The present findings support the hypothesis that vmPFC damage may impair affective systems specifically designed for mediating social transaction with other individuals.
尽管信任和互惠在社会交换中普遍存在，但它们的神经生物学基础在很大程度上仍不清楚。在这里，我们研究了腹内侧前额叶皮层（vmPFC）损伤对信任博弈和风险博弈中个体决策的影响。在信任博弈中，一个玩家，即投资者，被赋予一定数量的资金，她可以保留或投资这笔钱。她决定投资的金额将翻三倍并发送给另一个玩家，即受托人，然后受托人决定将多少份额返还给投资者。在单独的回合中，十名双侧 vmPFC 局灶性损伤患者和对照组参与者在每个回合中与不同的匿名对手分别扮演投资者或受托人的角色进行决策。还包括一个风险博弈，投资者在该博弈中面临与信任博弈完全相同的决策，但最终的收益由一个随机装置（即计算机）而不是另一个玩家决定。结果表明，vmPFC 患者的投资不受环境中存在的对手玩家类型（例如，人与计算机）的调节。因此，vmPFC 患者在社会（信任博弈）和非社会（风险博弈）情境中都表现出相似的风险偏好。相比之下，当控制参与者认为他们在与人类而不是计算机互动时，他们不太愿意冒险和投资。此外，作为受托人，vmPFC 患者向投资者的回传较少，因此表现出较少的互惠行为。综上所述，这些结果表明，由 vmPFC 介导的社会价值和情感在信任和互惠决策中起着关键作用。这些发现支持了这样一种假设，即 vmPFC 损伤可能会损害专门用于与其他个体进行社会交易的情感系统。
