Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford OX1 3SR, United Kingdom;
Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford OX1 3SR, United Kingdom.
Proc Natl Acad Sci U S A. 2020 May 26;117(21):11799-11810. doi: 10.1073/pnas.1921211117. Epub 2020 May 8.
Decisions about when to act are critical for survival in humans as in animals, but how a desire is translated into the decision that an action is worth taking at any particular point in time is incompletely understood. Here we show that a simple model developed to explain when animals decide it is worth taking an action also explains a significant portion of the variance in timing observed when humans take voluntary actions. The model focuses on the current environment's potential for reward, the timing of the individual's own recent actions, and the outcomes of those actions. We show, by using ultrahigh-field MRI scanning, that in addition to anterior cingulate cortex within medial frontal cortex, a group of subcortical structures including striatum, substantia nigra, basal forebrain (BF), pedunculopontine nucleus (PPN), and habenula (HB) encode trial-by-trial variation in action time. Further analysis of the activity patterns found in each area together with psychophysiological interaction analysis and structural equation modeling suggested a model in which BF integrates contextual information that will influence the decision about when to act and communicates this information, in parallel with PPN and HB influences, to nigrostriatal circuits. It is then in the nigrostriatal circuit that action initiation per se begins.
在人类和动物中，何时采取行动的决策对于生存至关重要，但一个愿望如何转化为在特定时间采取行动的决策，这一点还不完全清楚。在这里，我们展示了一个简单的模型，该模型用于解释动物何时决定采取行动，也解释了人类采取自愿行动时观察到的时间差异的很大一部分。该模型侧重于当前环境的奖励潜力、个体自身最近行动的时间以及这些行动的结果。我们通过使用超高场 MRI 扫描表明，除了内侧前额叶皮层中的前扣带皮层外，包括纹状体、黑质、基底前脑 (BF)、脑桥被盖核 (PPN) 和缰核 (HB) 在内的一组皮质下结构，编码了行动时间的逐次变化。对每个区域中发现的活动模式的进一步分析，以及心理生理相互作用分析和结构方程模型表明，BF 整合了将影响关于何时采取行动的决策的上下文信息，并与 PPN 和 HB 的影响并行，将信息传递给黑质纹状体回路。然后，正是在黑质纹状体回路中，行动本身才开始启动。
