Little attention has been paid to the post-decision processing in fMRI studies with task paradigms in which there was no explicit feedback. Although late-onset BOLD responses were previously observed in the lateral frontopolar cortex after the familiar-novel decision on visually presented words, the nature of neural activations that caused the late-onset BOLD responses remained elusive. We here found, in human experts conducting complicated problem-solving tasks in their expertise domain, that the rostral frontal cortex, including the lateral frontopolar cortex, along with the anterior inferior parietal lobule, was activated only during the post-decision period while there was no feedback. That is, these areas showed late-onset BOLD responses and fitting of the BOLD responses with different models indicates that they were caused by neural activations that occurred after the decision. However, there was no response after performing a sensory-motor control task and the magnitude of post-decision activations was correlated with the degree of uncertainty about the preceding decision, which suggest that the post-decision neural activations were associated with the preceding decision procedure. Furthermore, the same set of areas was more strongly activated when the subject explicitly re-thought the preceding problem. These results suggest that the rostral frontal cortex, together with anterior inferior parietal lobule, comprises a network for uncertainty monitoring and exploration of alternative resolutions in post-decision evaluation. The present results, thus, introduce a new aspect of the functional gradient along the rostro-caudal axis in the frontal cortex.
Significance Statement: After generating and selecting a solution for a given problem, we often evaluate the solution even without explicit feedback. This may be to change the solution when there is an opportunity for change, and, more generally, to deepen our understanding of similar problems. By using checkmate problems in Japanese chess, shogi, without giving any explicit feedback, we here found that the post-decision evaluation is mainly conducted by a frontoparietal network involving rostral frontal areas. These findings also introduce a new aspect of functional gradient in frontal cortex; post-decision evaluation in rostral areas and on-line task execution in caudal areas.
The authors declare no competing financial interests.
The Fujitsu Laboratories. The National Natural Science Foundation of China ; The 111 Project, China [B07008]