The nucleus accumbens core (NAc) is important for integrating and providing information to downstream areas about the timing and value of anticipated reward. Although NAc is one of the first brain regions to be affected by drugs of abuse, we still do not know how neural correlates related to reward expectancy are affected by previous cocaine self-administration. To address this issue, we recorded from single neurons in the NAc of rats that had previously self-administered cocaine or sucrose (control). Neural recordings were then taken while rats performed an odor-guided decision-making task in which we independently manipulated value of expected reward by changing the delay to or size of reward across a series of trial blocks. We found that previous cocaine self-administration made rats more impulsive, biasing choice behavior toward more immediate reward. Further, compared to controls, cocaine-exposed rats showed significantly fewer neurons in the NAc that were responsive during odor cues and reward delivery, and in the reward-responsive neurons that remained, diminished directional and value encoding was observed. Lastly, we found that after cocaine exposure, reward-related firing during longer delays was reduced compared to controls. These results demonstrate that prior cocaine self-administration alters reward-expectancy encoding in NAc, which could contribute to poor decision making observed after chronic cocaine use.

中文翻译：

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以前的可卡因自我管理会破坏腹侧纹状体的奖励期望编码。

伏伏核核心（NAc）对于整合和向下游地区提供有关预期奖励的时间和价值的信息非常重要。尽管NAc是第一个受滥用药物影响的大脑区域之一，但我们仍然不知道与可卡因的自我管理会如何影响与预期报酬相关的神经相关。为了解决这个问题，我们从先前可卡因或蔗糖（对照组）的大鼠NAc中记录了单个神经元。然后在大鼠执行气味引导的决策任务时进行神经记录，在该任务中，我们通过在一系列试验块中将奖励的延迟或奖励大小更改为独立地操纵预期奖励的值。我们发现以前的可卡因自我给药会使老鼠更冲动，将选择行为偏向更直接的奖励。此外，与对照组相比，接触可卡因的大鼠显示出在嗅觉提示和奖励传递过程中有响应的NAc中神经元明显减少，而在剩余的奖励响应神经元中，观察到方向和值编码减少。最后，我们发现可卡因暴露后，与对照组相比，较长时间的延误中与奖励相关的射击减少了。这些结果表明，以前的可卡因自我管理会改变NAc中的预期回报编码，这可能会导致长期使用可卡因后观察到的不良决策。观察到方向和值编码减少。最后，我们发现可卡因暴露后，与对照组相比，较长时间的延误中与奖励相关的射击减少了。这些结果表明，以前的可卡因自我管理会改变NAc中的预期回报编码，这可能会导致长期使用可卡因后观察到的不良决策。观察到方向和值编码减少。最后，我们发现可卡因暴露后，与对照组相比，较长时间的延误中与奖励相关的射击减少了。这些结果表明，以前的可卡因自我管理会改变NAc中的预期回报编码，这可能会导致长期使用可卡因后观察到的不良决策。