The source of Intellectual activity-Neural basis of Default activity

两只猴子接受了空间延迟交替（WM）任务的训练。我们检测了猴子在(1)有液体奖励的WM任务（WM任务期）和(2)没有任务表现和奖励的安静坐着（休息期）时多巴胺的释放情况。在WM任务期间，我们观察到内侧前额叶皮层（PFC）的多巴胺释放比REST期间显著减少。神经影像学研究表明，PFC背外侧的激活与WM任务表现有关，而PFC背外侧多巴胺释放的增加被认为在WM任务表现中起着重要作用。相比之下，在内侧PFC，我们观察到REST期间rCBF和多巴胺释放均比WM任务期间增加。我们的研究结果表明，内侧PFC中与默认模式大脑活动相关的认知操作可能受到多巴胺释放增加的支持。

Two monkeys were trained in a WM (spatial delayed alternation) task. We examined dopamine release while the monkey was (1) performing the WM task with a liquid reward (WM task period) and (2) sitting quietly without task performance and without reward (REST period). During the WM task period, we observed a significant decrease in dopamine release compared with during the REST period in the medial prefrontal cortex (PFC). Neuroimaging studies have indicated activations of the dorsolateral PFC in relation to WM task performance, and increased dopamine release in the dorsolateral PFC is considered to play essential roles in WM task performance. In contrast, in the medial PFC, we observed increases in both the rCBF and dopamine release during REST as compared with WM task period. Our results suggest that cognitive operations associated with default-mode brain activity in the medial PFC may be supported by the increased dopamine release.