Ernest Gallo Clinic and Research Center, University of California-San Francisco, 5858 Horton Street, Emeryville, CA 94608, USA.
Cereb Cortex. 2010 Dec;20(12):2884-99. doi: 10.1093/cercor/bhq036. Epub 2010 Mar 22.
The medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) are 2 structures within a larger corticolimbic network mediating goal-directed actions, especially when the procurement of different goals is sensitive to impulsive tendencies. The present study investigated the role of these structures in goal-directed action for differential reward by training rats to respond for sucrose reward at a nosepoke operandum such that longer duration nosepokes (up to 2 s) resulted in correspondingly larger volumes of reward. After 16 weeks of training, neurotoxic lesions of either the mPFC or the NAc-core were performed, followed by reassessment of sustained response behavior. Lesions of mPFC increased choice impulsivity by shifting responding away from large rewards toward rewards of smaller sizes. The total volume of reward earned remained unchanged, thereby dissociating the lesion effects on response parameters from overall motivation for reward. In contrast, NAc-core lesions decreased the total amount of responding and total volume of reward earned without altering choice impulsivity across differing nosepoke durations and reward sizes. These results suggest that the mPFC mediates the ability to maintain behavioral responding over longer durations for larger magnitude rewards, while the NAc-core mediates the initiation of responding, perhaps by affecting motivational drive, independent of reward magnitude.
内侧前额叶皮层（mPFC）和伏隔核（NAc）是介导目标导向行为的更大皮质边缘网络中的 2 个结构，特别是当获取不同目标对冲动倾向敏感时。本研究通过训练大鼠对鼻触操作器进行蔗糖奖励反应，以研究这些结构在目标导向行为中的作用，即较长时间的鼻触（最长可达 2 秒）会导致相应较大体积的奖励。经过 16 周的训练后，对 mPFC 或 NAc 核的神经毒性损伤进行了操作，然后重新评估了持续反应行为。mPFC 的损伤通过将反应从大奖励转移到较小奖励，增加了选择冲动性。获得的总奖励量保持不变，从而将损伤对反应参数的影响与对奖励的整体动机区分开来。相比之下，NAc 核损伤减少了总反应次数和总奖励量，而不改变不同鼻触持续时间和奖励大小下的选择冲动性。这些结果表明，mPFC 介导了为更大奖励保持较长时间的行为反应的能力，而 NAc 核介导了反应的启动，这可能通过影响动机驱动来实现，而与奖励大小无关。
