The Future of Memory: Remembering, Imagining, and the Brain

This article considers two recent lines of research concerned with the construction of imagined or simulated events that can provide insight into the relationship between memory and decision making. One line of research concerns episodic future thinking, which involves simulating episodes that might occur in one’s personal future, and the other concerns episodic counterfactual thinking, which involves simulating episodes that could have happened in one’s personal past. We first review neuroimaging studies that have examined the neural underpinnings of episodic future thinking and episodic counterfactual thinking. We argue that these studies have revealed that the two forms of episodic simulation engage a common core network including medial parietal, prefrontal, and temporal regions that also supports episodic memory. We also note that neuroimaging studies have documented neural differences between episodic future thinking and episodic counterfactual thinking, including differences in hippocampal responses. We next consider behavioral studies that have delineated both similarities and differences between the two kinds of episodic simulation. The evidence indicates that episodic future and counterfactual thinking are characterized by similarly reduced levels of specific detail compared with episodic memory, but that the effects of repeatedly imagining a possible experience have sharply contrasting effects on the perceived plausibility of those events during episodic future thinking versus episodic counterfactual thinking. Finally, we conclude by discussing the functional consequences of future and counterfactual simulations for decisions.

Episodic future thinking refers to the ability to imagine or simulate experiences that might occur in an individual’s personal future. It has been known for decades that cognitive aging is associated with declines in episodic memory, and recent research has documented correlated age-related declines in episodic future thinking. Previous research has considered both cognitive and neural mechanisms that are responsible for age-related changes in episodic future thinking, as well as effects of aging on the functions served by episodic future thinking. Studies concerned with mechanism indicate that multiple cognitive mechanisms contribute to changes in episodic future thinking during aging, including episodic memory retrieval, narrative style, and executive processes. Recent studies using an episodic specificity induction—brief training in recollecting episodic details of a recent experience—have proven useful in separating the contributions of episodic retrieval from other non-episodic processes during future thinking tasks in both old and young adults. Neuroimaging studies provide preliminary evidence of a role for age-related changes in default and executive brain networks in episodic future thinking and autobiographical planning. Studies concerned with function have examined age-related effects on the link between episodic future thinking and a variety of processes, including everyday problem-solving, prospective memory, prosocial intentions, and intertemporal choice/delay discounting. The general finding in these studies is for age-related reductions, consistent with the work on mechanisms that consistently reveals reduced episodic detail in older adults when they imagine future events. However, several studies have revealed that episodic simulation nonetheless confers some benefits for tasks tapping adaptive functions in older adults, such as problem-solving, prospective memory, and prosocial intentions, even though age-related deficits on these tasks are not eliminated or reduced by episodic future thinking.

<p>Episodic future thinking is defined as the ability to mentally project oneself into the future into a specific time and place. Episodic future thinking has been explored extensively in neuroscience. However, it has not been determined whether the measurement of episodic future thinking might be valuable in a clinical neuropsychological setting. The current study examined the relationship between episodic future thinking and instrumental activities of daily living (IADLs), which is a domain of adaptive functioning frequently assessed by neuropsychologists to examine independent living potential including the ability to handle finances, prepare food, complete household duties, and manage medications. A secondary aim was to examine whether episodic future thinking is related to IADLs over and above standard measures of cognition. 61 older adults with heterogeneous neurological conditions and 41 healthy older adults completed a future thinking task (the adapted Autobiographical Interview), two measures of IADLs (an informant report measure called the Everyday Cognition Scale and a performance-based measure called the Independent Living Scales), and standard measures of memory and executive functioning. Episodic future thinking was significantly associated with performance-based IADLs when accounting for age, education, gender, and depression (r=.26, p=.010). Episodic future thinking significantly predicted performance-based IADLs over and above executive functioning (R2=.025, p=.030). Episodic future thinking was not predictive of performance-based IADLs over and above memory (p=.157). Episodic future thinking was not significantly associated with informant reported IADLs when accounting for age, education, gender, and depression (p=.284). This study suggests that episodic future thinking is significantly associated with IADLs, beyond what can be accounted for by executive functioning. Episodic future thinking may provide information about IADLs to clinical neuropsychologists so they can improve their recommendations for independent living.</p>

Episodic future thinking is defined as the ability to mentally simulate a future event. Although episodic future thinking has been studied extensively in neuroscience, this construct has not been explored in depth from the perspective of clinical neuropsychology. The aim of this critical narrative review is to assess the validity and clinical implications of episodic future thinking. A systematic review of episodic future thinking literature was conducted. PubMed and PsycInfo were searched through July 2015 for review and empirical articles with the following search terms: "episodic future thinking," "future mental simulation," "imagining the future," "imagining new experiences," "future mental time travel," "future autobiographical experience," and "prospection." The review discusses evidence that episodic future thinking is important for adaptive functioning, which has implications for neurological populations. To determine the validity of episodic future thinking, the construct is evaluated with respect to related constructs, such as imagination, episodic memory, autobiographical memory, prospective memory, narrative construction, and working memory. Although it has been minimally investigated, there is evidence of convergent and discriminant validity for episodic future thinking. Research has not addressed the incremental validity of episodic future thinking. Practical considerations of episodic future thinking tasks and related constructs in a clinical neuropsychological setting are considered. The utility of episodic future thinking is currently unknown due to the lack of research investigating the validity of episodic future thinking. Future work is discussed, which could determine whether episodic future thinking is an important missing piece in standard clinical neuropsychological assessment. (PsycINFO Database Record

Is Episodic Future Thinking Important for Instrumental Activities of Daily Living? A Study in Neurological Patients and Healthy Older Adults.

Prospection, or future thinking, refers to the ability to mentally simulate plausible events at a future point in time and draws heavily upon the capacity to retrieve autobiographical details from the past. This review examines the extent to which prospection is compromised in neurodegenerative disorders with a view to identifying (1) underlying mechanisms of future thinking disruption and (2) the impact of future thinking deficits on everyday adaptive functioning. PubMed and MEDLINE were searched for peer-reviewed articles published or in press up to 14 October 2014. The key criterion for inclusion was that the primary outcome measure concerned the envisaging of episodic events at a future time point. Search terms of 'future thinking', 'prospection', and 'future simulation' were used in combination with the following terms: 'dementia', 'Mild Cognitive Impairment', 'Alzheimer's disease', 'semantic dementia', 'frontotemporal dementia', 'Parkinson's disease', 'Motor Neuron disease', 'Vascular dementia', and 'Dementia with Lewy bodies' (e.g., 'future thinking' AND 'Alzheimer's disease'). Searches were limited to articles published in English. A total of nine unique papers were identified in which prospection was the main outcome measure in dementia. Collectively, these studies reveal marked impairments in the ability to simulate personally relevant events at a future time point in dementia syndromes. Future research investigating the real-world implications of prospection deficits in dementia is crucial to elucidate the interplay between future-oriented thought and everyday adaptive functions such as prospective memory, decision-making, and maintaining a coherent sense of self over time.

The cognitive function to project oneself into the specific past or future is labeled mental time travel (MTT). MTT to the past is considered "episodic memory" and the future is termed "episodic future thinking". Remembering the past and imaging the future during MTT both draw on information stored in episodic memory: a process that enables integration of episodic information into a coherent event representation. Recent studies suggested that episodic information in past/future event representations varies with temporal distance from the present to the event. However, it is unclear whether the influence on temporal distance is actually caused by the function of episodic memory retrieval. The present study investigated the relationship between episodic memory and temporal concepts with a lexical decision task. The results indicate that remembering the past activated temporal concepts of the near future more than that of the far future. This finding suggests that the rich information derived from episodic memory modulates the subjective sense of time in episodic future thinking.

This article focuses on the neural and cognitive component processes that support the ability to imagine the future (episodic future thinking), which has recently been assumed to rely on the reconstructive nature of the episodic memory system. Functional neuroimaging studies have demonstrated the presence of a common core network, which underlies autobiographical remembering and future thinking. This network includes many regions traditionally associated with memory, such as the hippocampus and areas in the prefrontal cortex. However, inconsistent findings have emerged from recent studies of episodic future thinking in patients with amnesia and hippocampal damage, suggesting that imagining the future may not be entirely dependent on this structure. The existing evidence for impairments in future thinking in patients with prefrontal damage is at best either indirect, coming from studies of impaired planning and decision-making, or rest on a few case reports. Thus, the precise role of the hippocampus and prefrontal cortex in future thinking remains an open question. In this review, I consider findings from studies of patients with focal brain lesions with respect to current theoretical accounts for different component processes supporting the ability to envision the future and discuss the discrepant results within the literature.

The focus of this dissertation is on future prospection and goals in healthy aging. More broadly, this dissertation is contextualized within a particular theoretical framework that proposes that some of the cognitive decline associated with aging reflects adaptive changes in motivation and resource allocation (Hess, 2014). We used prospection as the cognitive domain within which to explore these motivational changes. In particular, we looked at a subtype of prospection known as episodic future thinking, which is concerned with how individuals imagine future scenarios, and what effects this might have on behaviour. Whereas the first experiment took up questions about motivational influences on the nature and bounds of future thinking deficits in older adults, the second experiment tested hypotheses about the adaptive function of future thinking. Specifically, episodic future thinking is often presumed to be adaptive for planning and successful action execution. Using prospective memory as a platform, we tested the idea that episodic future thinking can facilitate goal achievement, specifically in older adults. In the first experiment, a cue-word paradigm, with words chosen to reflect age-relevant goal domains, was used to prompt the imagination of future scenarios. The results from the first experiment suggest that contrary to predictions, goal activation does not affect level of episodic detail in future thinking. However, phenomenological characteristics were modulated, with younger adults showing more sensitivity than older adults. In the second experiment, participants employed different cognitive strategies – one of which included future thinking – in a gold standard test of prospective memory. The results from the second experiment failed to find episodic future thinking a helpful strategy and did not replicate previous work demonstrating a beneficial effect of another commonly used strategy, implementation intentions, which was used for comparison. Nonetheless, secondary analyses suggest that individual differences in strategy preference may be critical to consider before ruling out the utility of episodic future thinking. The results from these experiments contribute to a growing literature on motivation-cognition interactions across the lifespan, and suggest promising future directions regarding research into motivation, prospection, and healthy aging.

The focus of this dissertation is on future prospection and goals in healthy aging. More broadly, this dissertation is contextualized within a particular theoretical framework that proposes that some of the cognitive decline associated with aging reflects adaptive changes in motivation and resource allocation (Hess, 2014). We used prospection as the cognitive domain within which to explore these motivational changes. In particular, we looked at a subtype of prospection known as episodic future thinking, which is concerned with how individuals imagine future scenarios, and what effects this might have on behaviour. Whereas the first experiment took up questions about motivational influences on the nature and bounds of future thinking deficits in older adults, the second experiment tested hypotheses about the adaptive function of future thinking. Specifically, episodic future thinking is often presumed to be adaptive for planning and successful action execution. Using prospective memory as a platform, we tested the idea that episodic future thinking can facilitate goal achievement, specifically in older adults. In the first experiment, a cue-word paradigm, with words chosen to reflect age-relevant goal domains, was used to prompt the imagination of future scenarios. The results from the first experiment suggest that contrary to predictions, goal activation does not affect level of episodic detail in future thinking. However, phenomenological characteristics were modulated, with younger adults showing more sensitivity than older adults. In the second experiment, participants employed different cognitive strategies – one of which included future thinking – in a gold standard test of prospective memory. The results from the second experiment failed to find episodic future thinking a helpful strategy and did not replicate previous work demonstrating a beneficial effect of another commonly used strategy, implementation intentions, which was used for comparison. Nonetheless, secondary analyses suggest that individual differences in strategy preference may be critical to consider before ruling out the utility of episodic future thinking. The results from these experiments contribute to a growing literature on motivation-cognition interactions across the lifespan, and suggest promising future directions regarding research into motivation, prospection, and healthy aging.

The present study investigated temporal perception in a Huntington disease transgenic rat model using a temporal bisection procedure. After initial discrimination training in which animals learned to press one lever after a 2-s tone duration, and the other lever after a 8-s tone duration for food reward, the bisection procedure was implemented in which intermediate durations with no available reinforcement were interspersed with trials with the anchor durations. Bisection tests were repeated in a longitudinal design from 4 to 8 months of age. The results showed that response latencies evolved from a monotonic step-function to an inverted U-shaped function with repeated testing, a precursor of non-responding on trials with intermediate durations. We inferred that temporal sensitivity and incentive motivation combined to control the transformation of the bisection task from a two-choice task at the outset of testing to a three-choice task with repeated testing. Changes in the structure of the task and/or continued training were accompanied by improvement in temporal sensitivity. In sum, the present data highlight the possible joint roles of temporal and non-temporal factors in the temporal bisection task, and suggested that non-temporal factors may compensate for deficits in temporal processing.

Recent studies suggest that a brain network mainly associated with episodic memory has a more general function in imagining oneself in another time, place or perspective (e.g. episodic future thought, theory of mind, default mode). If this is true, counterfactual thinking (e.g. 'If I had left the office earlier, I wouldn't have missed my train.') should also activate this network. Present functional magnetic resonance imaging (fMRI) study explores the common and distinct neural activity of counterfactual and episodic thinking by directly comparing the imagining of upward counterfactuals (creating better outcomes for negative past events) with the re-experiencing of negative past events and the imagining of positive future events. Results confirm that episodic and counterfactual thinking share a common brain network, involving a core memory network (hippocampal area, temporal lobes, midline, and lateral parietal lobes) and prefrontal areas that might be related to mentalizing (medial prefrontal cortex) and performance monitoring (right prefrontal cortex). In contrast to episodic past and future thinking, counterfactual thinking recruits some of these areas more strongly and extensively, and additionally activates the bilateral inferior parietal lobe and posterior medial frontal cortex. We discuss these findings in view of recent fMRI evidence on the working of episodic memory and theory of mind.

Futures Studies as a multidisciplinary academic field developed in the last decades has emphasized the meaningful and revealing nature of the images of the future originating in every society. In this sense, Piotr M. Szpunar and Karl K. Szpunar (2016) underline the close relationship between recalling the past and imagining the future and suggest a mutual influence and interdependence between both processes. The purpose of this article is to apply the concept of “collective future thought” coined by these authors to the analysis of The Giver (1993) by Lois Lowry, which depicts a future dystopian society where memories of the past, as a powerful and threatening artifact, are kept away from the members of the community. This novel has been extensively analyzed as a dystopian text from many different perspectives. However, no critical attention has been paid to the way Lowry explores the close interrelationship and interdependence between the visions of past and future created by a society and their bonds of reciprocal interaction. Starting from a consideration of The Giver as dystopian fiction, this research attempts to move the critical exploration of this novel one step further and claims that a more nuanced understanding of the text can be achieved by considering the contributions from the field of Futures Studies and the concepts of collective memory and collective future thinking.

The ability to imagine the future is a complex mental faculty that depends on an ensemble of cognitive processes supported by an extended set of brain regions. Our aim here was to shed light on one key component of future thinking--personal goal processing--and to determine its neural correlates during both directed and spontaneous forms of thoughts. To address this question, we performed separate ALE meta-analyses of neuroimaging studies of episodic future thinking (EFT), mind-wandering, and personal goal processing, and then investigated the commonalities and differences in brain activity between these three domains. The results showed that the three domains activated a common set of brain regions within the default network and, most notably, the medial prefrontal cortex. This finding suggests that the medial prefrontal cortex mediates the processing of personal goals during both EFT and mind-wandering. Differences in activation were also observed, and notably regions supporting cognitive control processes (the dorsolateral prefrontal cortex) were recruited to a lesser extent during mind-wandering than experimentally directed future thinking, suggesting that different kinds of self-generated thoughts may recruit varying levels of attentional control abilities.

Episodic future thinking: mechanisms and functions