The role of ventromedial prefrontal cortex in reward valuation and future thinking during intertemporal choice

TLDR

Intertemporal choice involves balancing immediate versus delayed rewards, and damage to the ventromedial prefrontal cortex (vmPFC) leads to steeper discounting and impaired episodic future thinking, yet its precise role in reward valuation and future thinking during such decisions remains unclear. The study examined how vmPFC lesions affect intertemporal decision making by comparing 12 vmPFC patients with 41 healthy controls on choices between smaller‑immediate and larger‑delayed monetary rewards while varying reward magnitude and the presence of episodic future thinking cues. Participants imagined personal events at the delays associated with larger‑delayed rewards in the EFT condition, allowing the researchers to assess the influence of EFT cues on discounting behavior. Results showed that vmPFC patients discounted future rewards more steeply than controls and that reward magnitude did not alter this effect, but episodic future thinking cues reduced discounting in both groups, indicating vmPFC is essential for reward valuation but not for generating episodic future thinking during intertemporal choice.

Abstract

Intertemporal choices require trade-offs between short-term and long-term outcomes. Ventromedial prefrontal cortex (vmPFC) damage causes steep discounting of future rewards (delay discounting [DD]) and impoverished episodic future thinking (EFT). The role of vmPFC in reward valuation, EFT, and their interaction during intertemporal choice is still unclear. Here, 12 patients with lesions to vmPFC and 41 healthy controls chose between smaller-immediate and larger-delayed hypothetical monetary rewards while we manipulated reward magnitude and the availability of EFT cues. In the EFT condition, participants imagined personal events to occur at the delays associated with the larger-delayed rewards. We found that DD was steeper in vmPFC patients compared to controls, and not modulated by reward magnitude. However, EFT cues downregulated DD in vmPFC patients as well as controls. These findings indicate that vmPFC integrity is critical for the valuation of (future) rewards, but not to instill EFT in intertemporal choice.