Max Planck Institute for Human Development, D-14195 Berlin, Germany.
J Neurosci. 2012 Oct 24;32(43):14942-50. doi: 10.1523/JNEUROSCI.0573-12.2012.
Using neuroimaging in combination with computational modeling, this study shows that decision threshold modulation for reward maximization is accompanied by a change in effective connectivity within corticostriatal and cerebellar-striatal brain systems. Research on perceptual decision making suggests that people make decisions by accumulating sensory evidence until a decision threshold is crossed. This threshold can be adjusted to changing circumstances, to maximize rewards. Decision making thus requires effectively managing the amount of accumulated evidence versus the amount of available time. Importantly, the neural substrate of this decision threshold modulation is unknown. Participants performed a perceptual decision-making task in blocks with identical duration but different reward schedules. Behavioral and modeling results indicate that human subjects modulated their decision threshold to maximize net reward. Neuroimaging results indicate that decision threshold modulation was achieved by adjusting effective connectivity within corticostriatal and cerebellar-striatal brain systems, the former being responsible for processing of accumulated sensory evidence and the latter being responsible for automatic, subsecond temporal processing. Participants who adjusted their threshold to a greater extent (and gained more net reward) also showed a greater modulation of effective connectivity. These results reveal a neural mechanism that underlies decision makers' abilities to adjust to changing circumstances to maximize reward.
本研究结合神经影像学和计算建模，表明在追求最大化奖励的决策过程中，决策阈值的调节伴随着皮质纹状体和小脑纹状体脑系统内有效连接的变化。关于感知决策的研究表明，人们通过积累感官证据来做出决策，直到达到决策阈值。这个阈值可以根据变化的情况进行调整，以最大化奖励。因此，决策需要有效地管理积累的证据量与可用时间量。重要的是，这种决策阈值调节的神经基础尚不清楚。参与者在具有相同持续时间但不同奖励计划的块中执行感知决策任务。行为和建模结果表明，人类主体调节决策阈值以最大化净奖励。神经影像学结果表明，决策阈值的调节是通过调节皮质纹状体和小脑纹状体脑系统内的有效连接来实现的，前者负责处理积累的感官证据，后者负责自动、亚秒级的时间处理。那些更能调整阈值（并获得更多净奖励）的参与者也表现出更大的有效连接调节。这些结果揭示了一种神经机制，它是决策制定者适应变化环境以最大化奖励的能力的基础。
