The neural dissociation of subjective valuation from choice processes in intertemporal choice

摘要

During intertemporal choice, the neurobiological mechanism could include two process stages: a multicomponent valuation stage and a choice stage. Previous studies suggested that the contribution of subjective valuation may be recruited during the valuation stage, but that was absent during the choice stage. However, no studies have directly demonstrated the neural dissociation of subjective valuation from choice processes in intertemporal choice. Combining a novel, temporally distributed discounting task with event-related fMRI, we examined this hypothesis whether the neural substrates of subjective valuation were activated in the valuation stage, not in the choice stage. Behaviorally, participants discounted delayed rewards following a hyperbolic discounting function, and discount rates varied considerably between participants, reflecting different individual preferences. Ventral striatum (VStr), ventralmedial prefrontal cortical (vmPFC), and posterior cingulate cortical (PCC) activation were correlated strongly with the subjective valuation in the valuation stage, whereas dorsolateral prefrontal cortical (DLPFC), and inferior frontal gyrus (IFG) were correlated with choice processes in the choice stage. These findings suggest that mesolimbic dopamine projection regions show greater sensitivity to the subjective value during the valuation stage, and are absent during the choice stage, which demonstrates the neural dissociation of subjective valuation from choice processes in intertemporal choice.