Mental (future) event construction: component processes, neural bases, and role in decision making.

The present thesis addresses the cognitive and neural mechanisms underlying the construction of mental events and its role in decision-making. A specific form of mental event construction, episodic future thinking (EFT), has been a topic of intense inquiry, due to its purported adaptive role. EFT shares cognitive and neural mechanisms with episodic remembering, which has fuelled the discussion on its core component processes. To this aim, different theories have been advanced, focussing on the reconstructive nature of past memories, recombined into novel experiences, the self-projection into alternative situations underlying most forms of mental simulations, or the mental construction of scenes, seen as the backbones of either past, future and atemporal experiences. The first chapter delves into the relation between episodic memory and EFT, investigating multiple facets of future thinking in a patient with focal retrograde amnesia, and reveals that episodic remembering is crucial for EFT, less so for other forms of mental simulation for which semantic memory suffices, or for future-oriented decision making. The second chapter explores the neural bases of mental future event construction in patients with damage to the ventromedial prefrontal cortex (vmPFC), confirming a deficit in EFT in vmPFC patients, while excluding that this deficit depends on impairments in working memory or narrative abilities. The third chapter investigates whether a deficit in constructing (single) scenes may underly vmPFC patients' event construction impairment, studying scene construction in vmPFC and hippocampal patients. The chapter ends with a proposed model of the interaction of vmPFC and the hippocampus in which vmPFC initiates scene construction, and the hippocampus helps build cohesive scenes. The last chapter explores the adaptive role of EFT, showing that externally cueing EFT in vmPFC patients reduces their steep discounting of future rewards, further elucidating the role of vmPFC in mental event construction and in guiding future-oriented choice.