TRANSIENT ACTIVATION OF MIDBRAIN DOPAMINE NEURONS BY REWARD RISK
TRANSIENT ACTIVATION OF MIDBRAIN DOPAMINE NEURONS BY REWARD RISK
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DOI：
10.1016/j.neuroscience.2011.09.037
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发表时间：
2011-12-01
期刊：
影响因子：
3.3
通讯作者：
Fiorillo, C. D.
中科院分区：
文献类型：
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作者：
Fiorillo, C. D.
中脑腹侧的多巴胺神经元在预测未来奖励的刺激后会短暂激活。这种反应已被证明是对未来奖励的预期价值的信号，并且有强有力的证据表明，它推动了与奖励相关的刺激和行动的正强化，这与强化学习模型是一致的。行为也受到奖励不确定性或风险的影响，但尚不清楚多巴胺神经元的短暂反应是否对奖励风险敏感。为了研究这个问题，猴子被训练将不同的视觉刺激与一定或不确定的果汁量联系起来，这些果汁量几乎具有相同的期望值。在选择任务中，猴子更喜欢预测不确定（风险）奖励结果的刺激。在巴甫洛夫任务中，神经元对每个刺激的反应可以单独测量，研究发现多巴胺神经元被与奖励风险相关的刺激更强烈地激活。鉴于多巴胺驱动强化的大量证据，这些结果强烈表明，多巴胺神经元至少在某些条件下可以强化寻求风险的行为（赌博）。冒险行为具有促进探索和学习的优点，这些结果支持多巴胺神经元代表探索价值的假设。(c) 2011 ibro。Elsevier Ltd.出版。版权所有。
Dopamine neurons of the ventral midbrain are activated transiently following stimuli that predict future reward. This response has been shown to signal the expected value of future reward, and there is strong evidence that it drives positive reinforcement of stimuli and actions associated with reward in accord with reinforcement learning models. Behavior is also influenced by reward uncertainty, or risk, but it is not known whether the transient response of dopamine neurons is sensitive to reward risk. To investigate this, monkeys were trained to associate distinct visual stimuli with certain or uncertain volumes of juice of nearly the same expected value. In a choice task, monkeys preferred the stimulus predicting an uncertain (risky) reward outcome. In a Pavlovian task, in which the neuronal responses to each stimulus could be measured in isolation, it was found that dopamine neurons were more strongly activated by the stimulus associated with reward risk. Given extensive evidence that dopamine drives reinforcement, these results strongly suggest that dopamine neurons can reinforce risk-seeking behavior (gambling), at least under certain conditions. Risk-seeking behavior has the virtue of promoting exploration and learning, and these results support the hypothesis that dopamine neurons represent the value of exploration. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.