In neuroscience, evidence suggests that memory brain regions, such as the hippocampus, are involved in imagining novel situations. We conclude that hippocampus-mediated simulation plays a critical role in providing the motivation to pursue goals that are not present to our senses.Įconomic theory assumes that we assign some sort of value to options that are presented to us in order to choose between them. Conversely, patients with hippocampus atrophy due to Alzheimer's disease, but not patients with Fronto-Temporal Dementia, were less inclined to favor options that required mental simulation.
Structural MRI data suggested that grey matter density was a significant predictor of hippocampus activation, and therefore of the propensity to favor simulated options. Functional MRI data confirmed that hippocampus activity could account for subjects assigning higher values to simulated options.
Behavioral data showed that participants who imagined future options with greater details rated them as more likeable. To avoid confounding simulation process with delay discounting, we compared this ecological condition to control conditions using the same temporal labels while keeping constant the presentation mode. The ecological condition opposed immediate options presented as pictures (hence directly observable) to delayed options presented as texts (hence requiring mental stimulation). We developed a novel paradigm to assess the impact of hippocampus structure and function on the propensity to favor imagined outcomes in the context of intertemporal choices. We reasoned that the quality of hippocampus-mediated simulation might therefore condition the subjective value assigned to imagined outcomes. Many choice situations require imagining potential outcomes, a capacity that was shown to involve memory brain regions such as the hippocampus.