Bray Signe, O'Doherty John
Computation and Neural Systems, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
J Neurophysiol. 2007 Apr;97(4):3036-45. doi: 10.1152/jn.01211.2006. Epub 2007 Feb 15.
Attractive faces can be considered to be a form of visual reward. Previous imaging studies have reported activity in reward structures including orbitofrontal cortex and nucleus accumbens during presentation of attractive faces. Given that these stimuli appear to act as rewards, we set out to explore whether it was possible to establish conditioning in human subjects by pairing presentation of arbitrary affectively neutral stimuli with subsequent presentation of attractive and unattractive faces. Furthermore, we scanned human subjects with functional magnetic resonance imaging (fMRI) while they underwent this conditioning procedure to determine whether a reward-prediction error signal is engaged during learning with attractive faces as is known to be the case for learning with other types of reward such as juice and money. Subjects showed changes in behavioral ratings to the conditioned stimuli (CS) when comparing post- to preconditioning evaluations, notably for those CSs paired with attractive female faces. We used a simple Rescorla-Wagner learning model to generate a reward-prediction error signal and entered this into a regression analysis with the fMRI data. We found significant prediction error-related activity in the ventral striatum during conditioning with attractive compared with unattractive faces. These findings suggest that an arbitrary stimulus can acquire conditioned value by being paired with pleasant visual stimuli just as with other types of reward such as money or juice. This learning process elicits a reward-prediction error signal in a main target structure of dopamine neurons: the ventral striatum. The findings we describe here may provide insights into the neural mechanisms tapped into by advertisers seeking to influence behavioral preferences by repeatedly exposing consumers to simple associations between products and rewarding visual stimuli such as pretty faces.
迷人的面孔可被视为一种视觉奖励形式。先前的成像研究报告称，在呈现迷人面孔时，包括眶额皮质和伏隔核在内的奖励结构会出现活动。鉴于这些刺激似乎起到了奖励的作用，我们着手探究是否有可能通过将任意情感中性刺激的呈现与随后呈现迷人及不迷人面孔相结合，在人类受试者中建立条件反射。此外，我们在人类受试者进行这种条件反射程序时，用功能磁共振成像（fMRI）对他们进行扫描，以确定在以迷人面孔进行学习时，是否会像已知在以果汁和金钱等其他类型奖励进行学习时那样，出现奖励预测误差信号。与预处理评估相比，受试者在对条件刺激（CS）的行为评分上出现了变化，特别是对于那些与迷人女性面孔配对的CS。我们使用一个简单的雷斯克拉 - 瓦格纳学习模型来生成奖励预测误差信号，并将其纳入与fMRI数据的回归分析中。我们发现，与不迷人面孔相比，在以迷人面孔进行条件反射时，腹侧纹状体中存在与预测误差相关的显著活动。这些发现表明，一个任意刺激可以通过与愉悦的视觉刺激配对而获得条件价值，就像与金钱或果汁等其他类型奖励一样。这个学习过程在多巴胺神经元的一个主要目标结构——腹侧纹状体中引发了奖励预测误差信号。我们在此描述的发现可能为广告商的神经机制提供见解，这些广告商试图通过反复让消费者接触产品与诸如漂亮面孔等奖励性视觉刺激之间的简单关联来影响行为偏好。
