Dopamine neurons code subjective sensory experience and uncertainty of perceptual decisions
Dopamine neurons code subjective sensory experience and uncertainty of perceptual decisions
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DOI：
10.1073/pnas.1117636108
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发表时间：
2011-12-06
影响因子：
11.1
通讯作者：
Romo, Ranulfo
中科院分区：
文献类型：
--
作者：
de Lafuente, Victor;Romo, Ranulfo
中脑多巴胺（DA）神经元对与未来奖励相关的感官刺激做出反应。当奖励是概率性的，DA神经元反映这种不确定性，增加他们的放电率之间的一段时间的感觉线索和奖励传递时间。然而，奖励的可能性是通过视觉线索从外部传达的，我们不知道DA神经元是否会发出内部产生的不确定性信号。在这里，我们表明，DA神经元编码的不确定性与知觉判断的存在或不存在的振动触觉刺激。我们观察到，不确定性调制的活动引起的围棋线索指示猴子科目沟通他们的决定。也就是说，相同的go提示根据在go指令之前几秒做出的判断的不确定性水平而生成不同的DA响应。容易检测到的阈上刺激引起小DA反应，表明未来的奖励将不会是一个令人惊讶的事件。相反，感觉刺激的缺失会产生与不确定性相关的大的DA反应：刺激是真的不存在，还是低振幅的振动未被检测到？此外，DA神经元对刺激本身的反应随着振动幅度的增加而增加，但只有当猴子正确地检测到它的存在时。这一发现表明，DA活动是不相关的实际强度，而是感知强度。因此，除了它们在奖励预测中众所周知的作用之外，DA神经元还编码主观感觉体验和感知决策内部产生的不确定性。
Midbrain dopamine (DA) neurons respond to sensory stimuli associated with future rewards. When reward is delivered probabilistically, DA neurons reflect this uncertainty by increasing their firing rates in a period between the sensory cue and reward delivery time. Probability of reward, however, has been externally conveyed by visual cues, and it is not known whether DA neurons would signal uncertainty arising internally. Here we show that DA neurons code the uncertainty associated with a perceptual judgment about the presence or absence of a vibrotactile stimulus. We observed that uncertainty modulates the activity elicited by a go cue instructing monkey subjects to communicate their decisions. That is, the same go cue generates different DA responses depending on the uncertainty level of a judgment made a few seconds before the go instruction. Easily detected suprathreshold stimuli elicit small DA responses, indicating that future reward will not be a surprising event. In contrast, the absence of a sensory stimulus generates large DA responses associated with uncertainty: was the stimulus truly absent, or did a low-amplitude vibration go undetected? In addition, the responses of DA neurons to the stimulus itself increase with vibration amplitude, but only when monkeys correctly detect its presence. This finding suggests that DA activity is not related to actual intensity but rather to perceived intensity. Therefore, in addition to their well-known role in reward prediction, DA neurons code subjective sensory experience and uncertainty arising internally from perceptual decisions.