Parahippocampal–ventromedial prefrontal cortex functional coupling mediates the association between subjective time perception and delay discounting

Delay discounting (DD) refers to a decrease in the perceived value of an outcome when its delivery is delayed. Time perception (TP), the subjective awareness of the passage of time, is considered a critical factor enabling the modification of heightened DD. However, little is known about the neural mechanisms mediating the relationship between subjective TP and DD. To address this, we instructed participants to perform the TP task while watching scenic videos moving leftward or rightward, followed by the DD task, during brain scanning. We observed that subjective TP became faster while watching rightward scenic movies [the left-to-right (LtoR) condition, which is the participants' native language reading direction] compared to baseline, and there was a significant correlation between differences in subjective TP and DD between the LtoR condition and baseline. Seed-based connectivity analyses revealed a relationship between behavioral data, including TP and DD, and left parahippocampal seed connectivity under the LtoR condition. Subsequent mediation analysis revealed that the left parahippocampal seed-ventromedial prefrontal cortex functional connectivity mediated the relationship between subjective TP and DD. Our findings suggest a natural scenic effect on subjective TP manipulation and provide insights into the neural mechanisms mediating the relationship between subjective TP and DD.