Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA.
Neuroscience. 2010 Sep 15;169(4):1682-8. doi: 10.1016/j.neuroscience.2010.06.047. Epub 2010 Jun 25.
The mesolimbic dopamine system is critically involved in modulating reward-seeking behavior and is transiently activated upon presentation of reward-predictive cues. It has previously been shown, using fast-scan cyclic voltammetry in behaving rats, that cues predicting a variety of reinforcers including food/water, cocaine or intracranial self-stimulation (ICSS) elicit time-locked transient fluctuations in dopamine concentration in the nucleus accumbens (NAc) shell. These dopamine transients have been found to correlate with reward-related learning and are believed to promote reward-seeking behavior. Here, we investigated the effects of varying reinforcer magnitude (intracranial stimulation parameters) on cue-evoked dopamine release in the NAc shell in rats performing ICSS. We found that the amplitude of cue-evoked dopamine is adaptable, tracks reinforcer magnitude and is significantly correlated with ICSS seeking behavior. Specifically, the concentration of cue-associated dopamine transients increased significantly with increasing reinforcer magnitude, while, at the same time, the latency to lever press decreased with reinforcer magnitude. These data support the proposed role of NAc dopamine in the facilitation of reward-seeking and provide unique insight into factors influencing the plasticity of dopaminergic signaling during behavior.
中脑边缘多巴胺系统在调节奖励寻求行为方面起着至关重要的作用，并且在呈现奖励预测线索时会短暂激活。先前已经使用行为大鼠中的快速扫描循环伏安法证明，预测各种强化物（包括食物/水、可卡因或颅内自我刺激（ICSS））的线索会引发伏隔核（NAc）壳中多巴胺浓度的时间锁定瞬态波动。这些多巴胺瞬变被发现与奖励相关的学习有关，并被认为促进了奖励寻求行为。在这里，我们研究了在进行 ICSS 的大鼠中，改变强化物大小（颅内刺激参数）对 NAc 壳中线索诱发的多巴胺释放的影响。我们发现，线索诱发的多巴胺的幅度是可适应的，与强化物的大小有关，并且与 ICSS 寻求行为显著相关。具体来说，与线索相关的多巴胺瞬变的浓度随着强化物大小的增加而显著增加，而同时，压杆的潜伏期随着强化物大小的增加而减少。这些数据支持 NAc 多巴胺在促进奖励寻求中的作用，并为影响行为期间多巴胺能信号可塑性的因素提供了独特的见解。
