Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
Curr Biol. 2012 Oct 9;22(19):1839-44. doi: 10.1016/j.cub.2012.07.062. Epub 2012 Sep 6.
The time of reward and the temporal structure of reward occurrence fundamentally influence behavioral reinforcement and decision processes [1-11]. However, despite knowledge about timing in sensory and motor systems [12-17], we know little about temporal mechanisms of neuronal reward processing. In this experiment, visual stimuli predicted different instantaneous probabilities of reward occurrence that resulted in specific temporal reward structures. Licking behavior demonstrated that the animals had developed expectations for the time of reward that reflected the instantaneous reward probabilities. Neurons in the amygdala, a major component of the brain's reward system [18-29], showed two types of reward signal, both of which were sensitive to the expected time of reward. First, the time courses of anticipatory activity preceding reward delivery followed the specific instantaneous reward probabilities and thus paralleled the temporal reward structures. Second, the magnitudes of responses following reward delivery covaried with the instantaneous reward probabilities, reflecting the influence of temporal reward structures at the moment of reward delivery. In being sensitive to temporal reward structure, the reward signals of amygdala neurons reflected the temporally specific expectations of reward. The data demonstrate an active involvement of amygdala neurons in timing processes that are crucial for reward function.
奖励的时间和奖励发生的时间结构从根本上影响行为强化和决策过程[1-11]。然而，尽管我们了解感官和运动系统中的时间机制[12-17]，但对于神经元奖励处理的时间机制知之甚少。在这个实验中，视觉刺激预测了不同的即时奖励发生概率，从而产生了特定的时间奖励结构。舔舐行为表明，动物已经对奖励的时间产生了预期，这些预期反映了即时奖励概率。杏仁核中的神经元是大脑奖励系统的主要组成部分[18-29]，表现出两种类型的奖励信号，这两种信号都对预期的奖励时间敏感。首先，奖励传递前的预期活动的时间过程遵循特定的即时奖励概率，因此与时间奖励结构平行。其次，奖励传递后反应的幅度与即时奖励概率相关，反映了时间奖励结构在奖励传递时的影响。杏仁核神经元的奖励信号对时间奖励结构敏感，反映了对奖励的时间特异性预期。这些数据表明杏仁核神经元在时间过程中起着至关重要的作用，这对于奖励功能至关重要。
