Striatal dopamine release and motivated behavior

这个项目的目的是确定纹状体多巴胺释放在动机和强化中的作用。最近，我们发现大鼠乳上核的化学刺激是强化的，这表明乳上核可能是初级强化的一个组成部分。由于多巴胺在腹侧纹状体的释放与初级强化有关，我们研究了电刺激乳上核是否增强并唤起腹侧纹状体的多巴胺释放，如伏安信号所示。大鼠学会了杠杆按压，在乳上核上以200微a左右的电流提供短暂的电刺激序列。在乳上核上支持剧烈自我刺激的电刺激序列诱导多巴胺释放，这是伏安信号所显示的。乳上刺激引起的多巴胺信号的时间模式与腹侧被盖刺激引起的多巴胺信号的时间模式基本相同。这些结果表明，乳上核刺激触发腹侧纹状体释放多巴胺，这与初级强化有关，并且乳上核是与中边缘多巴胺系统相关的奖励回路的一部分。

The aim of this project is to determine the role of striatal dopamine release in motivation and reinforcement. Recently, we found that chemical stimulation of the supramammillary nucleus is reinforcing in rats, suggesting that the supramammillary nucleus may be a component of primary reinforcement. Since dopamine release in the ventral striatum has been implicated in primary reinforcement, we examined whether electrical stimulation of supramammillary nucleus is reinforcing and evokes dopamine release in the ventral striatum as shown by voltammetric signals. Rats learned to lever-press to deliver brief trains of electrical stimulation at the supramammillary nucleus with currents around 200 micro A. Electrical trains that support vigorous self-stimulation at the supramammillary area induced dopamine released as indicated by voltammetric signals. Temporal patterns of dopamine signals evoked by supramammillary stimulation are essentially identical to those of evoked by ventral tegmental stimulation. These results suggest that supramammillary stimulation triggers dopamine release in the ventral striatum, which has been implicated in primary reinforcement, and that the supramammillary nucleus is part of the reward circuitry associated with the meso-limbic dopamine system.