Department of Experimental Psychology, Ghent University, 9000 Ghent, Belgium, and Department of Psychology and Cognitive Science Center Amsterdam, University of Amsterdam, 1018 XA Amsterdam, The Netherlands.
J Neurosci. 2014 Feb 5;34(6):2148-54. doi: 10.1523/JNEUROSCI.1214-13.2014.
Decision-making involves weighing costs against benefits, for instance, in terms of the effort it takes to obtain a reward of a given magnitude. This evaluation process has been linked to the dorsal anterior cingulate cortex (dACC) and the striatum, with activation in these brain structures reflecting the discounting effect of effort on reward. Here, we investigate how cognitive effort influences neural choice processes in the absence of an extrinsic reward. Using functional magnetic resonance imaging in humans, we used an effort-based decision-making task in which participants were required to choose between two options for a subsequent flanker task that differed in the amount of cognitive effort. Cognitive effort was manipulated by varying the proportion of incongruent trials associated with each choice option. Choice-locked activation in the striatum was higher when participants chose voluntarily for the more effortful alternative but displayed the opposite trend on forced-choice trials. The dACC revealed a similar, yet only trend-level significant, activation pattern. Our results imply that activation levels in the striatum reflect a cost-benefit analysis, in which a balance is made between effort discounting and the intrinsic motivation to choose a cognitively challenging task. Moreover, our findings indicate that it matters whether this challenge is voluntarily chosen or externally imposed. As such, the present findings contrast with classical findings on effort discounting that found reductions in striatum activation for higher effort by finding enhancements of the same neural circuits when a cognitively challenging task is voluntarily selected and does not entail the danger of losing reward.
决策涉及权衡成本与收益，例如，就获得给定大小奖励所需的努力而言。这个评估过程与背侧前扣带皮层 (dACC) 和纹状体有关，这些大脑结构的激活反映了努力对奖励的折扣效应。在这里，我们研究了在没有外在奖励的情况下认知努力如何影响神经选择过程。使用功能性磁共振成像技术在人类中，我们使用了一种基于努力的决策任务，参与者需要在两种选择之间进行选择，以便在随后的侧翼任务中进行选择，而这两种选择在认知努力的程度上有所不同。通过改变与每个选择选项相关的不一致试验的比例来操纵认知努力。当参与者自愿选择更费力的替代方案时，纹状体的选择锁定激活更高，但在强制选择试验中则呈现相反的趋势。dACC 显示出类似的，但仅趋势水平显著的激活模式。我们的结果意味着纹状体的激活水平反映了成本效益分析，其中在努力折扣和选择认知挑战性任务的内在动机之间取得平衡。此外，我们的发现表明，这是否是自愿选择还是外部强加的很重要。因此，与经典的努力折扣发现相比，当自愿选择认知挑战性任务而不会有失去奖励的危险时，发现纹状体激活减少，而当自愿选择和不会有失去奖励的危险时，发现同一神经回路的增强。
