The neural system of metacognition accompanying decision-making in the prefrontal cortex

Decision-making is usually accompanied by metacognition, through which a decision maker monitors uncertainty regarding a decision and may then consequently revise the decision. These metacognitive processes can occur prior to or in the absence of feedback. However, the neural mechanisms of metacognition remain controversial. One theory proposes an independent neural system for metacognition in the prefrontal cortex (PFC); the other, that metacognitive processes coincide and overlap with the systems used for the decision-making process per se. In this study, we devised a novel “decision–redecision” paradigm to investigate the neural metacognitive processes involved in redecision as compared to the initial decision-making process. The participants underwent a perceptual decision-making task and a rule-based decision-making task during functional magnetic resonance imaging (fMRI). We found that the anterior PFC, including the dorsal anterior cingulate cortex (dACC) and lateral frontopolar cortex (lFPC), were more extensively activated after the initial decision. The dACC activity in redecision positively scaled with decision uncertainty and correlated with individual metacognitive uncertainty monitoring abilities—commonly occurring in both tasks—indicating that the dACC was specifically involved in decision uncertainty monitoring. In contrast, the lFPC activity seen in redecision processing was scaled with decision uncertainty reduction and correlated with individual accuracy changes—positively in the rule-based decision-making task and negatively in the perceptual decision-making task. Our results show that the lFPC was specifically involved in metacognitive control of decision adjustment and was subject to different control demands of the tasks. Therefore, our findings support that a separate neural system in the PFC is essentially involved in metacognition and further, that functions of the PFC in metacognition are dissociable.Author summary: Decision-making is often accompanied by a sense of uncertainty regarding the outcome. In many situations, there is no explicit feedback or cue to indicate whether the decision is correct or not. Fortunately, our brain can evaluate decision uncertainty using the internal signals and subsequently make appropriate adjustments to initial decisions. The process of considering the outcome of a decision and whether a decision should be adjusted is called metacognition, and it tends to be automatically induced. Thus, decision-making is usually accompanied by metacognition, and the two processes are inevitably coupled. However, the neural systems supporting metacognitive processing remain unclear and have often been misattributed to the neural system of the decision-making process per se. Here, we have analyzed this process in several volunteers by imaging the brain activity in specific regions while they performed Sudoku and random-dot motion (RDM) tasks. Our results suggest the existence of a neural system located in the prefrontal cortex (PFC) mainly involved in metacognition and independent from the neural system of decision-making.