Humanities and Social Sciences and Computational and Neural Systems, California Institute of Technology, Pasadena, CA 91125;
Virginia Tech Carilion Research Institute, Virginia Tech, Roanoke, VA 24016; and.
Proc Natl Acad Sci U S A. 2014 Jul 22;111(29):10503-8. doi: 10.1073/pnas.1318416111. Epub 2014 Jul 7.
Groups of humans routinely misassign value to complex future events, especially in settings involving the exchange of resources. If properly structured, experimental markets can act as excellent probes of human group-level valuation mechanisms during pathological overvaluations--price bubbles. The connection between the behavioral and neural underpinnings of such phenomena has been absent, in part due to a lack of enabling technology. We used a multisubject functional MRI paradigm to measure neural activity in human subjects participating in experimental asset markets in which endogenous price bubbles formed and crashed. Although many ideas exist about how and why such bubbles may form and how to identify them, our experiment provided a window on the connection between neural responses and behavioral acts (buying and selling) that created the bubbles. We show that aggregate neural activity in the nucleus accumbens (NAcc) tracks the price bubble and that NAcc activity aggregated within a market predicts future price changes and crashes. Furthermore, the lowest-earning subjects express a stronger tendency to buy as a function of measured NAcc activity. Conversely, we report a signal in the anterior insular cortex in the highest earners that precedes the impending price peak, is associated with a higher propensity to sell in high earners, and that may represent a neural early warning signal in these subjects. Such markets could be a model system to understand neural and behavior mechanisms in other settings where emergent group-level activity exhibits mistaken belief or valuation.
人类群体经常错误地给复杂的未来事件赋值，特别是在涉及资源交换的环境中。如果经过适当的构建，实验市场可以作为研究人类群体估值机制的极好工具，特别是在病理性高估——价格泡沫时期。这种现象的行为和神经基础之间的联系一直缺失，部分原因是缺乏相应的技术。我们使用多主体功能磁共振成像范式，来测量参与实验性资产市场的人类主体的神经活动，这些实验性资产市场中形成了内源性价格泡沫并最终崩溃。尽管有很多关于此类泡沫如何形成、如何识别的理论，但我们的实验提供了一个了解神经反应与行为（买卖）之间关系的窗口，这些行为促成了泡沫的形成。我们发现，伏隔核（NAcc）的整体神经活动可以追踪价格泡沫，而市场内部的 NAcc 活动可以预测未来的价格变化和崩溃。此外，收入最低的参与者表现出一种更强的倾向，即随着 NAcc 活动的增加而购买。相反，我们在收入最高的参与者的前脑岛皮层中报告了一个信号，该信号先于即将到来的价格峰值，与高收入者更高的卖出倾向相关，并且可能代表了这些参与者的神经预警信号。这样的市场可能是一个模型系统，可以帮助我们理解在其他环境中，新兴的群体活动表现出错误的信念或估值时的神经和行为机制。
