Components Of Prospective Memory Research Articles

Sleep Improves Prospective Remembering by Facilitating Spontaneous-Associative Retrieval Processes

Memories are of the past but for the future, enabling individuals to implement intended plans and actions at the appropriate time. Prospective memory is the specific ability to remember and execute an intended behavior at some designated point in the future. Although sleep is well-known to benefit the consolidation of memories for past events, its role for prospective memory is still not well understood. Here, we show that sleep as compared to wakefulness after prospective memory instruction enhanced the successful execution of prospective memories two days later. We further show that sleep benefited both components of prospective memory, i.e. to remember that something has to be done (prospective component) and to remember what has to be done (retrospective component). Finally, sleep enhanced prospective remembering particularly when attentional resources were reduced during task execution, suggesting that subjects after sleep were able to recruit additional spontaneous-associative retrieval processes to remember intentions successfully. Our findings indicate that sleep supports the maintenance of prospective memory over time by strengthening intentional memory representations, thus favoring the spontaneous retrieval of the intended action at the appropriate time.

Age effects in emotional prospective memory: Cue valence differentially affects the prospective and retrospective component.

While first studies suggested that emotional task material may enhance prospective memory performance in young and older adults, the extent and mechanisms of this effect are under debate. The authors explored possible differential effects of cue valence on the prospective and retrospective component of prospective memory in young and older adults. Forty-five young and 41 older adults performed a prospective memory task in which emotional valence of the prospective memory cue was manipulated (positive, negative, neutral). The multinomial model of event-based prospective memory was used to analyze effects of valence and age on the two prospective memory components separately. Results revealed an interaction indicating that age differences were smaller in both emotional valence conditions. For older adults positive cues improved the prospective component, while negative cues improved the retrospective component. No main effect of valence was found for younger adults on an overt accuracy measure, but model-based analyses showed that the retrospective component was enhanced in the positive compared with the negative cue condition. The study extends the literature in demonstrating that processes underlying emotional effects on prospective memory may differ depending on valence and age.

Can We Remember Future Actions yet Forget the Last Two Minutes? Study in Transient Global Amnesia

Transient global amnesia (TGA) is a clinical syndrome characterized by the abrupt onset of a massive episodic memory deficit that spares other cognitive functions. If the anterograde dimension is known to be impaired in TGA, researchers have yet to investigate prospective memory (PM)--which involves remembering to perform an intended action at some point in the future--in this syndrome. Furthermore, as executive functions are thought to be spared in this syndrome, TGA provides an opportunity to examine the impact of a massive "pure" memory impairment on PM. We assessed 38 patients with a newly designed protocol that distinguished between the prospective (remembering to do something at the appropriate time) and retrospective (remembering what has to be done) components of PM. Moreover, we investigated episodic memory with an anterograde memory task and assessed executive functions, anxiety and mood, as well as their links with PM. We demonstrated that PM is impaired during TGA, with a greater deficit for the retrospective component than for the prospective component. Furthermore, we highlighted a strong link between these two components. Anterograde episodic memory impairments were correlated with retrospective component deficits in TGA patients, although we were able to confirm that executive functions are globally spared. We discuss this pattern of results within the theoretical framework of PM, putting forward new arguments in favor of the idea that PM deficits can occur mainly because of a massive anterograde memory deficit. The clinical consequences of PM impairment in TGA are examined.

Prospective Memory Impairment in Mild Cognitive Impairment: An Analytical Review

Mild cognitive impairment (MCI) is a heterogeneous condition characterized by the presence in an otherwise healthy elderly individual of cognitive deficits involving specific domains in the absence of significant functional impairments. Reports indicate that prospective memory (PM), that is, the ability to remember to execute delayed intentions, is impaired in individuals with MCI. The present review discusses the current debate in the literature on PM functioning in MCI by focusing on the relationship between prospective retrieval and retrospective memory functioning. Analysis of the reported evidence revealed that both the prospective component and the retrospective component of PM can be impaired in MCI. Declarative memory dysfunction may account for the retrospective memory impairment, while either reduced executive abilities or a deficit of reflexive mechanisms could explain the prospective component impairment.

The contribution of retrospective memory, attention and executive functions to the prospective and retrospective components of prospective memory following TBI

Primary objective: Despite the prevalence of prospective memory (PM) problems, relatively little is known about the processes underlying impairment following TBI. This study sought to examine PM performance, using a multiple-task, multiple-response video-based paradigm in which initial encoding of the cue-action associations was ensured (Video-Assessment of Prospective Memory; VAPM).Research design: VAPM was designed to allow easy identification of reasons for failure (i.e. cue detection and/or specific action retrieval). Patients with moderate/severe TBI (n = 32) and matched controls (n = 16) also completed standardized neuropsychological assessment including evaluation of episodic retrospective memory (RM), attention, information processing, executive functions and mood.Main outcomes and results: As a group, those with TBI were impaired on PM tasks with 50% failing to complete at least 2/6 required tasks despite near perfect performance by controls. Individual profile analyses revealed different reasons for impairment, with RM contributing significantly to both the prospective and retrospective components. This was supported by correlational analyses illustrating a significant relationship between cue detection and RM measures, in addition to measures of executive functions and attention.Conclusions: The contribution of RM to both components of PM, along with the finding of heterogeneity in performance among participants have important implications for theoretical understanding and clinical practice.

Cognitive enhancement following acute losartan in normotensive young adults

Losartan, an angiotensin II receptor antagonist (AIIA), is an antihypertensive that has previously been suggested to have cognitive-enhancing potential for older adults. The objective indices for such effects are equivocal, however, and if these drugs do offer dual advantages of hypertension control plus cognitive-enhancing potential, there exists a clear need to establish this directly. This work examines the potential of losartan administered as a single dose to healthy young adults to improve cognitive performance alone or to reverse scopolamine-induced cognitive decrements. In two placebo-controlled, double-blind studies, participants completed a cognitive test battery once before and once after drug absorption. In experiment 1, participants were randomly allocated to receive placebo, losartan 50 mg or losartan 100 mg. In experiment 2, participants were randomly allocated to one of four treatment groups: placebo/placebo, placebo/scopolamine, losartan/scopolamine and losartan/placebo (50 mg losartan p.o. and 1.2 mg scopolamine hydrochloride p.o.). Losartan 50 mg improved performance on a task of prospective memory when administered alone and reversed the detrimental effects of scopolamine both in a standard lexical decision paradigm (p < 0.01) and when the task incorporated a prospective memory component (p < 0.008). The findings highlight a cognitive-enhancing potential for losartan on compromised cognitive systems and emphasise the potential of AIIAs to produce benefits over and above hypertension control.

Deficits in prospective memory following damage to the prefrontal cortex

Neuropsychological investigations of prospective memory (PM), representing memory of future intentions or plans, have evolved over the past two decades. The broadly accepted divisions involved in PM consist of a prospective memory component (PMC), a process for remembering to remember, and a retrospective memory component, a process for remembering the content of the intended action. Previous functional neuroimaing studies have provided some evidence that the rostral prefrontal cortex (BA10) is one of areas that is critical for prospective remembering. However, the question of whether damage to part of the prefrontal cortex affects attenuated performance for PMC remains unresolved. In this study, 74 participants with traumatic brain injury (TBI) including focal damage to frontal or temporal lobe areas were administered thirteen standard neuropsychological tests and the PM task. To identify influential areas contributing to PM performance, discriminant function analysis was conducted. The results indicated that the following three areas are highly contributory to PM performance: the right dorsolateral prefrontal cortex; the right ventromedial prefrontal cortex; and the left dorsomedial prefrontal cortex. Comparing differences in neuropsychological test scores showed that orientation scores were significantly higher in the greater PM performance group, suggesting that PMC represents an integrated memory function associated with awareness of current status. These data contribute to our understanding of the neural substrates and functional characteristics of the PMC.

Ecological prospective memory assessment in patients with traumatic brain injury

Primary objective: Prospective memory (PM) impairments are often observed after traumatic brain injury (TBI). Although PM is crucial for daily functioning, few sensitive, valid and ecological clinical tests are available. To address these concerns, the authors developed a PM task, the TEMP, using naturalistic stimuli, in which each PM phase and component is evaluated independently in time- and event-based conditions.Main outcomes and results: The results show that moderate and severe TBI patients (n = 30), evaluated after spontaneous neurological recovery, experienced problems in learning the delayed intentions content and retrieving these intentions in the right context (prospective component), especially in the time-based condition. They also recalled fewer associated actions (retrospective component), but only in the time-based condition. Correlations revealed that the retrospective component was mainly supported by episodic retrospective memory processes, while the prospective component was supported by episodic retrospective memory processes, along with attentional and executive functions. Moreover, there was a significant correlation between performance on the TEMP and results on a questionnaire assessing PM functioning in daily living completed by participants’ relatives.Conclusions: The TEMP therefore appears to be a sensitive tool for assessing PM problems that combines internal and ecological validity.

The development of prospective memory in typically developing children.

This study aimed to use specifically designed tasks to capture time-based, activity-based, and event-based prospective memory (PM) performance in typically developing school-age children. Two PM tasks (Fishing Game & Happy Week) were used to examine the developmental patterns of PM in these children. Retrospective memory (RM) was also examined in these tasks. A total of 120 children aged between 7 and 12 years (10 girls and 10 boys in each age band) were recruited. Tests of working memory, inhibition, and IQ were also administered. The age effect on PM accuracy was significant, with improvements identified between ages 7 to 8 and 10 to 11 years. For both tasks, performance on the time-based PM task was significantly poorer than that on the event-based PM task, which in turn was significantly poorer than that on the activity-based PM task. In terms of errors, results indicated that while errors associated with the PM component of the tasks decreased with age, errors associated with the RM component showed an inverted-U shape. The different patterns of errors suggest qualitative as well as quantitative differences in PM development in children. Finally, IQ, working memory, and inhibition were found to relate to PM when age was partialed out. Results of the study highlight the importance of contextual cues, such as activities and events, for prospective remembering in children. In addition, they have provided a general picture of PM development in school-age children and have implications for educators and parents.

The neuropsychology of prospective memory in normal aging: A componential approach

To guide understanding of the neuropsychology of prospective memory and aging, we highlight several components of prospective memory, including planning an intended action, retrieving the action at the appropriate moment, and executing the action. We posit that frontal systems are particularly important for prospective memory tasks that require planning, that require strategic monitoring to detect the appropriate moment for executing the prospective memory intention, or for which execution of the retrieved intention must be delayed briefly. Drawing from a variety of approaches, including neuroimaging (with young adults) and studies examining individual differences relating to frontal functioning, we assemble preliminary evidence that supports this hypothesis. Further, because aging especially disrupts frontal functioning, the above noted prospective memory tasks would thus be expected to display the greatest age-related decline. The available literature confirms this expectation. A second key hypothesis is that some prospective memory tasks—those requiring minimal planning and supporting spontaneous retrieval—do not rely extensively on frontal processes but instead rely on medial-temporal structures for reflexive retrieval. These prospective memory tasks tend to show minimal or no age-related decline. The literature, though sparse with regard to the neuropsychological underpinnings of this kind of prospective memory task, is consistent with the present hypothesis.

Age-related Declines in Prospective Memory: Modulation of the Prospective and Retrospective Components

Prospective memory (PM) is defined as remembering to remember or remembering to perform an intended action, which requires to form and later realize intentions that must be delayed for minutes, hours, or days, such as remembering to take medication with a meal, or to turn off the stove after cooking. Prospective memory is important in our everyday life, especially to those old people with declined (i.e., less efficient) cognitive functions. Better prospective memory performance can help old people maintain their independent lives and improve their quality of life. So the present study focused on the age difference in an event-based prospective memory task. Regarding the internal mechanism of age differences in PM, two contradictive perspectives were proposed: the age deficits exist in prospective component VS in retrospective component. Noticing-search model (Einstein McDaniel, 1996) suggested that the PM deficit in old people came from the searching process. On the other hand, Smith and Bayen (2006) applied a formal multinomial processing tree model of PM and indicated that the deficit existed in the process of recognizing target cues, which was resource-demanding. The present study evaluated the two perspectives and further investigated the related cognitive mechanism using a classic paradigm where the prospective memory task was embedded in a semantic categorization task. 60 young (29 females) and 60 old adults (26 females) participated experiment 1 voluntarily. The experiment compared the effect of age on the prospective component and the retrospective component of PM, manipulating semantic relatedness between cue and intention, and the distinctiveness of the cue. Young adults performed better than old adults in both the prospective component and retrospective component, but the effect size of age was larger in prospective component. When the relatedness was high or the cue was distinctive, old adults performed as well as young adults, however, it showed age deficits when the relatedness was low or the cue was indistinguishable.These findings suggest that both data-driven and conceptually driven processes can improve old people's memory for intentions greatly.Another 68 young (37 females) and 68 old adults (46 females) participated in Experiment 2. The experiment examined the effect of prospective component on the age difference in prospective memory by reducing the demand of retrospective component and manipulating the cognitive resources of prospective memory. Main effect of age, the distractive level of divided attention and the distinctiveness of the target cue were all found in the accuracy of prospective memory. Both the response time of ongoing and PM tasks had a significant decline in the older adults compared to the young ones. Significant age deficits were found when the target was indistinguishable. And the high distractive level task made old adults’ performance even worse. To be summarized, the aging of PM is modulated both by data-driven and conceptually driven processes. Compared to retrospective component, the age effect in PM is greater on the prospective component. The cognitive load in the task influences the age effect in PM since the prospective component is resource-demanding. The age effect is more obvious when the PM task needs more strategic control than automatically processed. These results further reveal the cause of the reasons for age differences in prospective memory.

Neural correlates of attentional and mnemonic processing in event-based prospective memory

Prospective memory (PM), or memory for realizing delayed intentions, was examined with an event-based paradigm while simultaneously measuring neural activity with high-density EEG recordings. Specifically, the neural substrates of monitoring for an event-based cue were examined, as well as those perhaps associated with the cognitive processes supporting detection of cues and fulfillment of intentions. Participants engaged in a baseline lexical decision task (LDT), followed by a LDT with an embedded PM component. Event-based cues were constituted by color and lexicality (red words). Behavioral data provided evidence that monitoring, or preparatory attentional processes, were used to detect cues. Analysis of the event-related potentials (ERP) revealed visual attentional modulations at 140 and 220 ms post-stimulus associated with preparatory attentional processes. In addition, ERP components at 220, 350, and 400 ms post-stimulus were enhanced for intention-related items. Our results suggest preparatory attention may operate by selectively modulating processing of features related to a previously formed event-based intention, as well as provide further evidence for the proposal that dissociable component processes support the fulfillment of delayed intentions.

Multitasking and prospective memory: can virtual reality be useful for diagnosis?

Prospective memory (PM) is defined as the ability to perform an intended action in the future [4]. It is with this type of memory that one can observe the highest number of memory errors made within the context of everyday life [6]. Furthermore, researchers have demonstrated that prospective memory is extremely sensitive to traumatic brain injury (TBI) [5]. In the past few years, research in the field of PM has shown how the frontal lobes are involved in the context of multitasking. Multitasking is defined by the ability to execute and monitor a set of “goal-oriented” behaviours in order to realize planned actions [3]. Shallice and Burgess [8] have discussed the importance of multitasking as an essential component of prospective memory. During the last few years, neuropsychological tests have been criticized, especially with regard to everyday functioning. At present, neuropsychological tools sometimes fail to detect subtle and complex deficits in the goal-oriented behaviours in order to realise selfplanned actions [8]. We now seem to have at our disposal virtual reality (VR) to compensate for the different limits of traditional assessment. One of the major plusses of VR is its capacity to bring the real world into a labora-

Prospective memory impairment in individuals with Parkinson's disease.

This study investigated prospective memory and its relationship to executive and memory functions in persons with Parkinson's disease (PD). Twenty-three individuals with PD and 25 healthy comparison participants participated in the study. In the prospective memory tasks, participants were asked to execute 3 actions after 20 min (time-based condition) or after a timer ring (event-based condition). A score was computed for the correct recall of the intention to perform the actions (prospective component) and for the correct execution of the actions (retrospective component). Participants with PD also received an extensive neuropsychological test battery. PD participants were less accurate than comparison participants in the prospective component of the time-based but not the event-based task. Individuals with PD were also impaired on the retrospective component of both tasks. In the PD group, a general trend toward significant correlations was found between performance level on the prospective memory component of the time-based task and scores on executive and working memory measures. These results document that prospective memory is impaired in PD possibly in relation to a dysregulation of cognitive functions associated with frontal systems.

Differential effects of depressive symptoms on prospective and retrospective memory in old age

The effects of depressive symptoms on prospective and retrospective memory were examined in a population-based sample of elderly persons (n = 404). Depression was assessed using the Comprehensive Psychopathological Rating Scale and treated as a continuous variable. The variation in depressive symptoms ranged from no symptoms to presence of a clinical depression. Depressive symptoms had a negative effect on consolidation and retrieval in retrospective memory. However, the retrospective, but not the prospective, component of prospective memory was affected by depression. The findings are discussed in light of medial-temporal lobe alterations in depression.

Prospective memory and mesial temporal epilepsy associated with hippocampal sclerosis

Episodic memory impairment is commonly observed in patients with epilepsy associated with mesial temporal sclerosis (MTS). Prospective memory (PM) is a set cognitive abilities that allow future performance of a present intention, in response to time- or event-based evocation cues, that trigger the intended action at the appropriate time. PM has not been evaluated in mesial temporal sclerosis. We evaluated the role of right and left hippocampal lesions on performance in both the retrospective and prospective PM components in patients with epilepsy secondary to mesial temporal sclerosis and correlated with performance in traditional neuropsychological tests, as well as with self-perception of memory impairment. We tested the hypotheses that a hippocampal lesion impacts on the prospective components of PM, and that a left-sided lesion had a greater impact on performance in the prospective component of PM than a right-sided lesion. We evaluated PM in 26 patients with right MTS, 22 left MTS patients, and 26 age–gender and education matched controls. The prospective component of PM was impaired in both patient groups, with both a lesion (patients performed significantly worse in the PM battery) and laterality effect (left MTS patients performed significantly worse than right MTS patients in the PM battery). Performance in the prospective component of the PM battery correlated with long-term delay performance in episodic verbal memory and self-perception of memory impairment in the left MTS group. The retrospective component was impaired in left MTS patients. Impaired performance was not accounted for solely by depression, anxiety or an antiepileptic drug effect. We conclude that mesial temporal lobe structures, including the hippocampus, play an important role in both the prospective and retrospective components of PM processes in tasks involving long delay intervals.

Neural correlates of prospective memory across the lifespan

Overview Behavioural data reveal an inverted U-shaped function in the efficiency of prospective memory from childhood to young adulthood to later adulthood. However, prior research has not directly compared processes contributing to age-related variation in prospective memory across the lifespan, hence it is unclear whether the same factors explain the ‘rise and fall’ of prospective remembering from childhood to later adulthood. The present study examined this question using a paradigm that allowed us to consider the behavioural and neural correlates of processes associated with the prospective and retrospective components of prospective memory. Methods We compared 14 adolescents, 14 young adults, and 14 old adults in a paradigm where the prospective memory task was embedded in a semantic categorization task. Results The behavioural data revealed an inverted U-shaped function with adolescents and old adults performing poorly relative to young adults. Analyses of the error data revealed that different processes may have contributed to failures of prospective memory in adolescents and older adults. This finding was supported by age differences in ERP-components for cue detection and post-retrieval processes. Additionally, source localization using LORETA revealed different patterns of neural recruitment for adolescents and older adults relative to younger adults. Conclusion Our findings demonstrate that adolescents and older adults show different patterns of behavioural errors and neural recruitment for successful prospective remembering indicating that different processes may contribute to the ‘rise and fall’ of prospective memory across the lifespan.

Differential components of prospective memory?: Evidence from fMRI

Two of the principal components of prospective memory (i.e., remembering to carry out delayed intentions) are recognizing the appropriate context to act (“cue identification”) and remembering the action to be performed (“intention retrieval”). In this experiment, the demands on these components were manipulated while measuring brain activity using fMRI to explore whether the two components share a common neural basis. The results showed significant behavioral differences between the cue identification and intention retrieval conditions. However, a consistent pattern of hemodynamic changes was found in both prospective memory conditions in anterior prefrontal cortex (BA 10), with lateral BA 10 activation accompanied by medial BA 10 deactivation. These effects were more pronounced when demands on intention retrieval were high. This is consistent with the hypothesis that anterior prefrontal cortex (area 10) supports the biasing of attention between external events (e.g., identifying the cue amid distracting stimuli) and internal thought processes (i.e., maintaining the intention and remembering the intended actions). Together, the results suggest that whilst cue identification and intention retrieval may be behaviorally separable, they share at least some common neural basis in anterior prefrontal cortex.

Dissociative Contributions of Medial Temporal and Frontal Regions to Prospective Remembering

Prospective memory is memory of future intentions or plans in everyday life. Although some previous neuropsychological studies have stated that the prefrontal cortex and the medial temporal lobe are essential for successful prospective remembering, how the two regions contribute to prospective remembering remains unclear. We therefore used prospective memory training in the present study to investigate the neural mechanism of two components of prospective remembering: remembering to remember and remembering content. Two brain-damaged patients participated in this study: patient Y.O., who had lesions in the medial temporal lobe bilaterally, and patient T.K., who had a lesion in the basal forebrain and right medial frontal lobe. Both participants exhibited a severe anterograde amnesic syndrome and had normal IQ scores. Before the prospective memory training the participants underwent several index memory tests to examine their general memory and prospective memory performance. The training consisted of requesting the participants to perform an original mini-day task, in which they were first asked to memorize five simple daily actions with their times for execution, and then to recall the content of the actions when shown a drawing of a clock showing the proper time for execution. A training session was carried out once a week for 3 months. After completing training, the participants were again requested to take the same index memory tests. The results of the training task showed that Y.O.'s memory performance had gradually improved across all sessions of training, but T.K.'s improvement was not as marked. A more detailed analysis revealed that Y.O.'s memory performance was better for recalling time than for recalling content, whereas T.K.'s memory performance was better for recalling content than for recalling time. Furthermore, the results of the final index memory tests showed that the only improvement in Y.O.'s prospective memory was in remembering to remember, and that the only improvement in T.K.'s prospective memory was in remembering content. These results provide strong evidence that these two remembering components of prospective memory have independent neural bases, with the basal forebrain and right medial frontal lobe being required for remembering to remember, and the medial temporal lobe being required for remembering content. The results also suggest that memory training is an effective, means of improving everyday memory.

The effect of perceptual distinctiveness on the prospective and retrospective components of prospective memory in young and old adults.

In two experiments, the effect of perceptual distinctiveness of cues on prospective memory performance was examined. Young and older adults completed a visual search task with embedded prospective memory instructions. On each trial, participants were asked to indicate the position of a target letter in a letter string, unless either of two letters previously identified as prospective memory cues was presented. Each prospective cue was associated with a specific response. Perceptual distinctiveness was manipulated by spatially displacing a single letter. The prospective component (successful detection of the cue) and the retrospective memory component (recalling the correct response when a cue is detected) were measured separately. Perceptual displacement of cues modulated performance of the prospective component but not the retrospective component. Young adults successfully detected a larger proportion of cues (prospective component) than older adults. However, there were minimal effects of age and no effect of cue displacement on participants' ability to recall the intention once they detected a cue (retrospective component performance). Results are discussed within the context of current theoretical models of prospective memory.