Implausible future events in a confabulating patient with an anterior communicating artery aneurysm

Stuck in the here and now: Construction of fictitious and future experiences following ventromedial prefrontal damage

There is increasing interest in uncovering the cognitive and neural bases of episodic future thinking (EFT), the ability to imagine events relevant to one's own future. Recent functional neuroimaging evidence shows that the ventromedial prefrontal cortex (vmPFC) is engaged during EFT. However, vmPFC is also activated during imagination of fictitious, atemporal experiences. Therefore, its role in EFT is currently unclear. To test (1) whether vmPFC is critical for EFT, and (2) whether it supports EFT specifically, or, rather, construction of any complex experience, patients with focal lesions to vmPFC (vmPFC patients), control patients with lesions not involving vmPFC, and healthy controls were asked to imagine personal future experiences and fictitious experiences. Compared to the control groups, vmPFC patients were impaired at imagining both future and fictitious experiences, indicating a general deficit in constructing novel experiences. Unlike the control groups, however, vmPFC patients had more difficulties in imagining future compared to fictitious experiences. Exploratory correlation analyses showed that general construction deficits correlated with lesion volume in BA 11, whereas specific EFT deficits correlated with lesion volume in BA 32 and BA 10. Together, these findings indicate that vmPFC is crucial for EFT. We propose, however, that different vmPFC subregions may support different component processes of EFT: the most ventral part, BA 11, may underlie core constructive processes needed to imagine any complex experience (e.g., scene construction), whereas BA 10 and BA 32 may mediate simulation of those specific experiences that likely await us in the future.

Amnesia and future thinking: Exploring the role of memory in the quantity and quality of episodic future thoughts

OBJECTIVES

To examine the impact of memory accessibility on episodic future thinking.

DESIGN

Single-case study of neurological patient HCM and an age-matched comparison group of neurologically Healthy Controls.

METHODS

We administered a full battery of tests assessing general intelligence, memory, and executive functioning. To assess autobiographical memory, the Autobiographical Memory Interview (Kopelman, Wilson, & Baddeley, 1990. The Autobiographical Memory Interview. Bury St. Edmunds, UK: Thames Valley Test Company) was administered. The Past Episodic and Future Episodic sections of Dalla Barba's Confabulation Battery (Dalla Barba, 1993, Cogn. Neuropsychol., 1, 1) and a specifically tailored Mental Time Travel Questionnaire were administered to assess future thinking in HCM and age-matched controls.

RESULTS

HCM presented with a deficit in forming new memories (anterograde amnesia) and recalling events from before the onset of neurological impairment (retrograde amnesia). HCM's autobiographical memory impairments are characterized by a paucity of memories from Recent Life. In comparison with controls, two features of his future thoughts are apparent: Reduced episodic future thinking and outdated content of his episodic future thoughts.

CONCLUSIONS

This article suggests neuropsychologists should look beyond popular conceptualizations of the past-future relation in amnesia via focussing on reduced future thinking. Investigating both the quantity and quality of future thoughts produced by amnesic patients may lead to developments in understanding the complex nature of future thinking disorders resulting from memory impairments.

PRACTITIONER POINTS

We highlight the clinical importance of examining the content of future thoughts in amnesic patients, rather than only its quantitative reduction. We propose an explanation of how quantitative and qualitative aspects of future thinking could be affected by amnesia. This could provide a useful approach to understand clinical cases of impaired prospection.

LIMITATIONS

Systematic group investigations are required to fully examine our hypothesis. Although the current study utilized typical future thinking measures, these may be limited and we highlight the need to develop clinically relevant measures of prospection.

Making the future memorable: The phenomenology of remembered future events

Although our ability to remember future simulations conveys an adaptive advantage, enabling us to better prepare for upcoming events, the factors influencing the memorability of future simulations are not clear. In this study, participants generated future simulations that combined specific people, places and objects from memory, and for each trial, made a series of phenomenological ratings about the event components and the simulation as a whole. Memory for simulations was later assessed using a cued-recall test. We used multilevel modelling to determine whether the phenomenological qualities of event components (familiarity, emotionality and significance) and simulations (detail, plausibility) were predictive of whether the simulation was successfully encoded and later accessible. Our results demonstrate that person familiarity, detail and plausibility were significant predictors of whether a given future simulation was encoded into memory and later accessible. These findings suggest that scaffolding future simulations with pre-existing episodic memories is the path to a memorable future.