Regulating how fast to learn is critical for flexible behavior. Learning about the consequences of actions should be slow in stable environments, but accelerate when that environment changes. Recognizing stability and detecting change is difficult in environments with noisy relationships between actions and outcomes. Under these conditions, theories propose that uncertainty can be used to modulate learning rates ("meta-learning"). We show that mice behaving in a dynamic foraging task exhibit choice behavior that varied as a function of two forms of uncertainty estimated from a meta-learning model. The activity of dorsal raphe serotonin neurons tracked both types of uncertainty in the foraging task, as well as in a dynamic Pavlovian task. Reversible inhibition of serotonin neurons in the foraging task reproduced changes in learning predicted by a simulated lesion of meta-learning in the model. We thus provide a quantitative link between serotonin neuron activity, learning, and decision making.

中文翻译：

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血清素神经元通过不确定性调节学习率

调节学习速度对于灵活的行为至关重要。在稳定的环境中，对动作后果的了解应该是缓慢的，但是当环境发生变化时，了解则要加快。在行动与结果之间存在嘈杂关系的环境中，很难识别稳定性并检测变化。在这些条件下，理论提出不确定性可用于调节学习率（“元学习”）。我们表明，表现出动态觅食任务的小鼠表现出的选择行为随从元学习模型估计的两种不确定性形式而变化。背缝血清素神经元的活动跟踪了觅食任务以及动态巴甫洛夫任务中的两种不确定性。在觅食任务中对5-羟色胺神经元的可逆抑制，再现了模型中元学习的模拟病变所预测的学习变化。因此，我们提供了5-羟色胺神经元活动，学习和决策之间的定量联系。