Liu Xun, Powell David K, Wang Hongbin, Gold Brian T, Corbly Christine R, Joseph Jane E
Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky 40536, USA.
J Neurosci. 2007 Apr 25;27(17):4587-97. doi: 10.1523/JNEUROSCI.5227-06.2007.
Reward-seeking behavior depends critically on processing of positive and negative information at various stages such as reward anticipation, outcome monitoring, and choice evaluation. Behavioral and neuropsychological evidence suggests that processing of positive (e.g., gain) and negative (e.g., loss) reward information may be dissociable and individually disrupted. However, it remains uncertain whether different stages of reward processing share certain neural circuitry in frontal and striatal areas, and whether distinct but interactive systems in these areas are recruited for positive and negative reward processing. To explore these issues, we used a monetary decision-making task to investigate the roles of frontal and striatal areas at all three stages of reward processing in the same event-related functional magnetic resonance imaging experiment. Participants were instructed to choose whether to bet or bank a certain number of chips. If they decided to bank or if they lost a bet, they started over betting one chip. If they won a bet, the wager was doubled in the next round. Positive reward anticipation, winning outcome, and evaluation of right choices activated the striatum and medial/middle orbitofrontal cortex, whereas negative reward anticipation, losing outcome, and evaluation of wrong choices activated the lateral orbitofrontal cortex, anterior insula, superior temporal pole, and dorsomedial frontal cortex. These findings suggest that the valence of reward information and counterfactual comparison more strongly predict a functional dissociation in frontal and striatal areas than do various stages of reward processing. These distinct but interactive systems may serve to guide human's reward-seeking behavior.
寻求奖励行为在很大程度上取决于在奖励预期、结果监测和选择评估等各个阶段对正面和负面信息的处理。行为和神经心理学证据表明，对正面（如收益）和负面（如损失）奖励信息的处理可能是可分离的，且会分别受到干扰。然而，奖励处理的不同阶段在额叶和纹状体区域是否共享某些神经回路，以及这些区域中不同但相互作用的系统是否被用于正面和负面奖励处理，仍不确定。为了探究这些问题，我们在同一事件相关功能磁共振成像实验中，使用金钱决策任务来研究额叶和纹状体区域在奖励处理的所有三个阶段中的作用。参与者被指示选择是下注还是储存一定数量的筹码。如果他们决定储存或者下注输了，他们重新开始下注一个筹码。如果他们下注赢了，赌注在下一轮翻倍。正面奖励预期、获胜结果以及对正确选择的评估激活了纹状体和内侧/中间眶额皮质，而负面奖励预期、输的结果以及对错误选择的评估激活了外侧眶额皮质、前岛叶、颞上极和背内侧额叶皮质。这些发现表明，奖励信息的效价和反事实比较比奖励处理的各个阶段更能有力地预测额叶和纹状体区域的功能分离。这些不同但相互作用的系统可能有助于指导人类的寻求奖励行为。
