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OBJECTIVE: Functional neuroimaging and lesion studies show that the ventromedial prefrontal cortex (vmPFC) is implicated in episodic future thinking (EFT), yet its role remains unclear. In this study, we sought to (a) confirm recent findings of impaired EFT in patients with lesions to the vmPFC (vmPFC patients) using a new task, and (b) investigate the influence of nonepisodic mechanisms, namely, narrative construction and working memory maintenance, on vmPFC patients' EFT performance. METHOD: vmPFC patients and healthy participants imagined future events using pictures as cues, described pictures, or described pictures while maintaining them in working memory after an observation phase. RESULTS: Compared with the controls, vmPFC patients produced less specific reports across all conditions, as indicated by fewer internal (episodic) but a similar number of external (semantic) details. However, controlling for description and working memory performance did not eliminate group differences in EFT. Moreover, vmPFC damage reduced the proportion of internal-to-total details for EFT only. CONCLUSIONS: These results indicate that EFT problems in vmPFC patients are not merely the reflection of problems in maintaining in working memory and narrating events, but, more likely, of an impairment upstream, in creating novel events. (PsycINFO Database Record

The ability to project oneself into the past and future to relive or pre-live personal experiences, known as mental time travel (MTT), is associated with activity in a core network of brain regions involving the ventromedial prefrontal cortex (vmPFC). We investigated whether (1) vmPFC is crucial for MTT, and (2) whether vmPFC is selectively involved in the construction of self-relevant events or also mediates construction of events happening to others. Patients with lesions to vmPFC (vmPFC patients) and healthy controls remembered personal past events and imagined personal future events across different timeframes, and imagined events to happen to a close or a distant other. Compared to the controls, vmPFC patients were impaired at constructing both past and future events, indicating that vmPFC is critical for MTT. vmPFC patients' ability to imagine personal future events was related to patients' temporal discounting rates. Patients, however, were also impaired at imagining other-related events, suggesting that self-relevance may not be a critical factor in explaining vmPFC's involvement in MTT. We suggest that vmPFC is crucial for the imagination of complex experiences alternative to the current reality, which serves construction of both self-relevant and other-relevant events.

Mind-wandering, an ubiquitous expression of humans' mental life, reflects a drift of attention away from the current task towards self-generated thoughts, and has been associated with activity in the brain default network. To date, however, little is understood about the contribution of individual nodes of this network to mind-wandering. Here, we investigated whether the ventromedial prefrontal cortex (vmPFC) is critically involved in mind-wandering, by studying the propensity to mind-wander in patients with lesion to the vmPFC (vmPFC patients), control patients with lesions not involving the vmPFC, and healthy individuals. Participants performed three tasks varying in cognitive demands while their thoughts were periodically sampled, and a self-report scale of daydreaming in daily life. vmPFC patients exhibited reduced mind-wandering rates across tasks, and claimed less frequent daydreaming, than both healthy and brain-damaged controls. vmPFC damage reduced off-task thoughts related to the future, while it promoted those about the present. These results indicate that vmPFC critically supports mind-wandering, possibly by helping to construct future-related scenarios and thoughts that have the potential to draw attention inward, away from the ongoing tasks.

We studied episodic memory and future thinking for self-relevant and other-relevant events at different levels of retrieval support, theory of mind, and delay discounting in ASD children and adolescents (ASDs). Compared to typically developing controls, ASDs produced fewer internal (episodic) but a similar number of external (semantic) details while remembering past events, imagining future events, and imagining future events happening to others, indicating a general impairment of event construction. This deficit was driven by group differences under high retrieval support, and therefore unlikely to depend on self-initiated retrieval/construction deficits. ASDs' event construction impairment related to the severity of ASD symptoms, and to theory of mind deficits. ASDs, however, showed normal delay discounting, highlighting preserved forms of future-based decision-making in ASD.

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.

A new test of coherent form discrimination called Form Test is proposed in order to assess ventral stream functionality. The task consists of shape discrimination among 8 different forms. The form is obtained by a number white luminance coherent dots presented on a circular black background. Stimuli are presented in 5 levels of spatial coherence by increasing noise dots. Noise dots are non aligned and non coherent luminance dots which disturb shape discrimination. A sample of 163 children (75 females and 88 males, age range: 5-12) is considered. Results show significant differences among coherence levels: the number of correct answers decreases with noise increment. Moreover, the age of children affect the scores: the performance of children in Form Test improves with age. The results confirm that Form Test can be an helpful instrument to measure the ventral stream functionality and shows its sensitivity to the age differences.