Table_1_Stimulating the Dorsolateral Prefrontal Cortex Decreases the Asset Bubble: A tDCS Study.xlsx

Many studies have discussed the neural basis of asset bubbles. They found that the dorsolateral prefrontal cortex (DLPFC) played an important role in bubble formation, but whether a causal relationship exists and the mechanism of the effect of the DLPFC on bubbles remains unsettled. Using transcranial direct current stimulation (tDCS), we modulated the activity of the DLPFC and investigated the causal relationship between the DLPFC and the asset bubble in the classical learning-to-forecast experiment. 126 subjects were randomly divided into three groups and received different stimulations (left anodal/right cathodal, right anodal/left cathodal, or sham stimulation), respectively. We also conducted a 2-back task before and after stimulation to measure changes in subjects’ cognitive abilities and explore in detail the cognitive mechanism of the effect of DLPFC stimulation on asset bubbles. Based on our results, we found that the bubble of the left anodal/right cathodal stimulation group was significantly smaller than that of the sham stimulation group. In the meantime, subjects performed significantly better in the 2-back task after left anodal/right cathodal stimulation but not right anodal/left cathodal or sham stimulation, which is consistent with their performance in the learning-to-forecast experiment, supporting the cognitive mechanism to some extent. Furthermore, we examined different forecasting rules across individuals and discovered that the left anodal/right cathodal stimulation group preferred the adaptive learning rule, while the sham and right anodal/left cathodal stimulation groups adopted a pure trend-following rule that tended to intensify market volatility aggressively.

已有多项研究探讨了资产泡沫的神经基础。研究发现，背外侧前额叶皮层（dorsolateral prefrontal cortex, DLPFC）在泡沫形成过程中发挥重要作用，但二者是否存在因果关系，以及DLPFC影响资产泡沫的具体机制仍未明确。本研究采用经颅直流电刺激（transcranial direct current stimulation, tDCS）调节DLPFC的活动，并在经典的学习预测实验中探究DLPFC与资产泡沫之间的因果关系。126名被试被随机分为三组，分别接受不同刺激：左侧阳极/右侧阴极刺激、右侧阳极/左侧阴极刺激，或伪刺激。我们还在刺激前后开展了2-back任务，以测量被试认知能力的变化，进而细致探讨DLPFC刺激影响资产泡沫的认知机制。基于研究结果，我们发现左侧阳极/右侧阴极刺激组的资产泡沫规模显著小于伪刺激组。与此同时，接受左侧阳极/右侧阴极刺激的被试在2-back任务中的表现显著优于刺激前，而右侧阳极/左侧阴极刺激组与伪刺激组则无此变化，这一结果与他们在学习预测实验中的表现相符，在一定程度上验证了前述认知机制。此外，我们对个体间不同的预测规则进行了分析，发现左侧阳极/右侧阴极刺激组更倾向于采用自适应学习规则，而伪刺激组与右侧阳极/左侧阴极刺激组则采用纯粹的趋势追踪规则，这类规则往往会大幅加剧市场波动。