Unraveling the neural basis of repeated moral decisions with mouse tracking and fMRI.

Tracking response history and current rewards is critical for making moral decisions. By integrating functional magnetic resonance imaging (fMRI) and mouse tracking (MT) with a value-based moral decision task, we quantify the level of choice conflict with the MT metric-area under the curve (AUC), and examine how individuals incorporate information from the response history to make repeated moral decisions. Our study uses response entropy and cumulative responses (CR) to define choice consistency on both the subject level and trial level. We find that a stronger correlation between AUC and response entropy is mediated by the weight of reward in decisions. Regarding the fMRI results, the precuneus tracks AUC and increases across time. Across the whole brain, we compare the pattern of how the human brain encodes AUC with several NeuroSynth templates, and find that neural similarity of reward decreased and was correlated with entropy and the weight of relative reward. Meanwhile, multivariate representations in cognitive control and self-referential brain regions such as inferior frontal gyrus (IFG), anterior cingulate cortex (ACC), and temporoparietal junction (TPJ) encode the weight of relative reward and CR together. Finally, the functional connectivity (FC) analysis show that ACC, as well as the FC between ACC and precuneus, becomes more prominent across time. Through understanding choice conflict and response history, our research sheds light on its significance in multi-trial moral decision from the consistency perspective. These findings establish a foundation for exploring the underlying mechanisms involved in repeated decisions with conflict processes.