The role of the medial prefrontal cortex in risk and time preferences: A tDCS study.

Risk and time preferences are fundamental determinants of economic decision making. Although medial prefrontal cortex (mPFC) activity has been associated with valuation across these domains, causal evidence that focal mPFC perturbation alters both risky and intertemporal choices remains limited. In this research, we applied anodal, cathodal, or sham transcranial direct current stimulation (tDCS) to mPFC and administered a battery of risky lotteries and a Convex Time Budget task that jointly elicits risk and intertemporal trade-offs. Our results indicate that individuals who received cathodal stimulation were more likely to choose safe lotteries and to allocate their tokens to an earlier date rather than future dates; these effects were statistically reliable in nonparametric tests and remained evident after covariate adjustment. This co-modulation of both preferences following mPFC perturbation provides causal evidence that the mPFC supports a shared valuation component and can co-modulate both risky and delayed choices. Our findings clarify the mPFC's specific causal role within the broader neural circuitry governing economic preferences.