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首页> 外文期刊>Journal of Neurophysiology >Predictive reward signal of dopamine neurons.
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Predictive reward signal of dopamine neurons.

机译：多巴胺神经元的预测性奖励信号。

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The effects of lesions, receptor blocking, electrical self-stimulation, and drugs of abuse suggest that midbrain dopamine systems are involved in processing reward information and learning approach behavior. Most dopamine neurons show phasic activations after primary liquid and food rewards and conditioned, reward-predicting visual and auditory stimuli. They show biphasic, activation-depression responses after stimuli that resemble reward-predicting stimuli or are novel or particularly salient. However, only few phasic activations follow aversive stimuli. Thus dopamine neurons label environmental stimuli with appetitive value, predict and detect rewards and signal alerting and motivating events. By failing to discriminate between different rewards, dopamine neurons appear to emit an alerting message about the surprising presence or absence of rewards. All responses to rewards and reward-predicting stimuli depend on event predictability. Dopamine neurons are activated by rewarding events that are better than predicted, remain uninfluenced by events that are as good as predicted, and are depressed by events that are worse than predicted. By signaling rewards according to a prediction error, dopamine responses have the formal characteristics of a teaching signal postulated by reinforcement learning theories. Dopamine responses transfer during learning from primary rewards to reward-predicting stimuli. This may contribute to neuronal mechanisms underlying the retrograde action of rewards, one of the main puzzles in reinforcement learning. The impulse response releases a short pulse of dopamine onto many dendrites, thus broadcasting a rather global reinforcement signal to postsynaptic neurons. This signal may improve approach behavior by providing advance reward information before the behavior occurs, and may contribute to learning by modifying synaptic transmission. The dopamine reward signal is supplemented by activity in neurons in striatum, frontal cortex, and amygdala, which process specific reward information but do not emit a global reward prediction error signal. A cooperation between the different reward signals may assure the use of specific rewards for selectively reinforcing behaviors. Among the other projection systems, noradrenaline neurons predominantly serve attentional mechanisms and nucleus basalis neurons code rewards heterogeneously. Cerebellar climbing fibers signal errors in motor performance or errors in the prediction of aversive events to cerebellar Purkinje cells. Most deficits following dopamine-depleting lesions are not easily explained by a defective reward signal but may reflect the absence of a general enabling function of tonic levels of extracellular dopamine. Thus dopamine systems may have two functions, the phasic transmission of reward information and the tonic enabling of postsynaptic neurons.
机译：损害，受体阻滞，自我电刺激和滥用药物的影响表明，中脑多巴胺系统参与处理奖励信息和学习方法行为。大多数的多巴胺神经元在主要的液体和食物奖励以及有条件的，奖励预测的视觉和听觉刺激后显示出阶段性激活。它们在刺激后表现出双相的，激活-抑制反应，类似于奖励预测的刺激，或者是新颖的或特别显着的。但是，只有很少的阶段性激活遵循厌恶性刺激。因此，多巴胺神经元以环境价值标记环境刺激，预测和检测奖励并发出警报和激励事件。由于无法区分不同的奖励，多巴胺神经元似乎发出有关奖励存在或不存在的惊人提示。对奖励和奖励预测刺激的所有响应都取决于事件的可预测性。多巴胺神经元通过奖励比预期更好的事件而被激活，而不受与预期一样好的事件的影响，而由于不良于预期的事件而被压抑。通过根据预测误差发出奖励信号，多巴胺反应具有强化学习理论所假定的教学信号的形式特征。在学习过程中，多巴胺反应从初级奖励转换为预测奖励的刺激。这可能有助于奖赏逆行作用的神经元机制，这是强化学习的主要难题之一。冲动反应将短波多巴胺释放到许多树突上，从而向突触后神经元广播相当全面的增强信号。该信号可以通过在行为发生之前提供预先的奖励信息来改善进近行为，并且可以通过修改突触传递来促进学习。多巴胺奖励信号由纹状体，额叶皮层和杏仁核中神经元的活动所补充，这些神经元处理特定的奖励信息，但不会发出全局奖励预测错误信号。不同奖励信号之间的合作可以确保使用特定奖励来选择性地增强行为。在其他投影系统中，去甲肾上腺素神经元主要充当注意力机制，而基底核神经元编码的奖励异质性。小脑攀爬纤维向小脑浦肯野细胞发出运动性能错误或厌恶事件预测错误的信号。消耗多巴胺的病变后的大多数缺陷不易通过有缺陷的奖赏信号来解释，但可能反映出缺乏细胞外多巴胺的补品水平的一般启用功能。因此，多巴胺系统可能具有两种功能，即奖励信息的阶段性传递和突触后神经元的补药作用。

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