为了能在受欢迎的餐厅吃饭，有些人愿意在门口排一个小时的队。日本一个研究小组通过动物实验揭示，为获得想要的东西而耐心等待的时候，大脑内分泌血清素的神经细胞会变得活跃。

日本冲绳科学技术研究所的一个研究小组在新一期美国《神经科学杂志》上发表论文说，他们以大白鼠为对象进行实验，在大白鼠想要食物或水的时候，不马上给它们提供，而是让它们等一段时间。研究人员把电极固定在大白鼠的脑部，以记录它们在等待食物时候的神经活动。

研究人员发现，实验鼠在等待时，其大脑内分泌血清素的神经细胞会变得活跃，这部分神经细胞分泌血清素的频率提高到通常情况下的3倍左右，实验鼠脑内血清素的浓度也相应升高，而中途放弃等待实验鼠的这部分神经细胞活动在它们放弃的几秒前出现变弱。

血清素是一种神经传递素。此前的研究显示，如果抑制脑内血清素发挥作用，人会变得容易采取冲动的行动。

这项成果有助于研究注意力缺陷多动障碍（ADHD）等伴有冲动症状疾病的发病原因，并有助于开发相应的治疗方法。

原文出处：

The Journal of Neuroscience January 12, 2011, 31(2):469-479; doi:10.1523/JNEUROSCI.3714-10.2011

Activation of Dorsal Raphe Serotonin Neurons Underlies Waiting for Delayed Rewards

Katsuhiko Miyazaki,1 Kayoko W. Miyazaki,1 and Kenji Doya1,2

1Neural Computation Unit, Okinawa Institute of Science and Technology, Okinawa 904-0412, Japan, and 2Computational Neuroscience Laboratories, Advanced Telecommunications Research Institute International, Kyoto 619-0288, Japan

The serotonergic system plays a key role in the control of impulsive behaviors. Forebrain serotonin depletion leads to premature actions and steepens discounting of delayed rewards. However, there has been no direct evidence for serotonin neuron activity in relation to actions for delayed rewards. Here we show that serotonin neurons increase their tonic firing while rats wait for food and water rewards and conditioned reinforcement tones. The rate of tonic firing during the delay period was significantly higher for rewards than for tones, for which rats could not wait as long. When the delay was extended, tonic firing persisted until reward or tone delivery. When rats gave up waiting because of extended delay or reward omission, serotonin neuron firing dropped preceding the exit from reward sites. Serotonin neurons did not show significant response when an expected reward was omitted, which was predicted by the theory that serotonin signals negative reward prediction errors. These results suggest that increased serotonin neuron firing facilitates a rat's waiting behavior in prospect of forthcoming rewards and that higher serotonin activation enables longer waiting.