Incentive effects on event-based prospective memory performance in children and adolescents with traumatic brain injury

I Won't Forget to Do It If It's Important: A Multinomial Processing Tree Analysis of Social Importance and Monetary Reward on Event-Based Prospective Memory

While previous research has suggested that prospective memory may be enhanced by providing a social motive (i.e., social importance) or by promising a monetary reward for successful performance, to the best of our knowledge, the underlying mechanisms responsible for these effects are still largely unexplored. In a sample of 96 younger adults, this study investigated how social importance and promising a monetary reward influence the prospective component and the retrospective component of event-based prospective memory separately, with the application of a multinomial modeling approach. Results revealed enhanced prospective memory performance for all importance conditions compared to a standard condition. This improvement was characterized by an increased allocation of resource-demanding attentional processes in performing the prospective memory task at the expense of the ongoing task without an increase in the perceived importance of the prospective memory task. The model-based analyses showed that the beneficial effects of importance arise from an increased engagement of the prospective component, leaving the estimates for the retrospective component unaffected.

Prefrontal cortical activation associated with prospective memory while walking around a real-world street environment

Rostral PFC (area 10) activation is common during prospective memory (PM) tasks. But it is not clear what mental processes these activations index. Three candidate explanations from cognitive neuroscience theory are: (i) monitoring of the environment; (ii) spontaneous intention retrieval; (iii) a combination of the two. These explanations make different predictions about the temporal and spatial patterns of activation that would be seen in rostral PFC in naturalistic settings. Accordingly, we plotted functional events in PFC using portable fNIRS while people were carrying out a PM task outside the lab and responding to cues when they were encountered, to decide between these explanations. Nineteen people were asked to walk around a street in London, U.K. and perform various tasks while also remembering to respond to prospective memory (PM) cues when they detected them. The prospective memory cues could be either social (involving greeting a person) or non-social (interacting with a parking meter) in nature. There were also a number of contrast conditions which allowed us to determine activation specifically related to the prospective memory components of the tasks. We found that maintaining both social and non-social intentions was associated with widespread activation within medial and right hemisphere rostral prefrontal cortex (BA 10), in agreement with numerous previous lab-based fMRI studies of prospective memory. In addition, increased activation was found within lateral prefrontal cortex (BA 45 and 46) when people were maintaining a social intention compared to a non-social one. The data were then subjected to a GLM-based method for automatic identification of functional events (AIDE), and the position of the participants at the time of the activation events were located on a map of the physical space. The results showed that the spatial and temporal distribution of these events was not random, but aggregated around areas in which the participants appeared to retrieve their future intentions (i.e., where they saw intentional cues), as well as where they executed them. Functional events were detected most frequently in BA 10 during the PM conditions compared to other regions and tasks. Mobile fNIRS can be used to measure higher cognitive functions of the prefrontal cortex in "real world" situations outside the laboratory in freely ambulant individuals. The addition of a "brain-first" approach to the data permits the experimenter to determine not only when haemodynamic changes occur, but also where the participant was when it happened. This can be extremely valuable when trying to link brain and cognition.

Effective connectivity in the default mode network after paediatric traumatic brain injury

Children who experience a traumatic brain injury (TBI) are at elevated risk for a range of negative cognitive and neuropsychological outcomes. Identifying which children are at greatest risk for negative outcomes can be difficult due to the heterogeneity of TBI. To address this barrier, the current study applied a novel method of characterizing brain connectivity networks, Bayesian multi-subject vector autoregressive modelling (BVAR-connect), which used white matter integrity as priors to evaluate effective connectivity-the time-dependent relationship in functional magnetic resonance imaging (fMRI) activity between two brain regions-within the default mode network (DMN). In a prospective longitudinal study, children ages 8-15 years with mild to severe TBI underwent diffusion tensor imaging and resting state fMRI 7 weeks after injury; post-concussion and anxiety symptoms were assessed 7 months after injury. The goals of this study were to (1) characterize differences in positive effective connectivity of resting-state DMN circuitry between healthy controls and children with TBI, (2) determine if severity of TBI was associated with differences in DMN connectivity and (3) evaluate whether patterns of DMN effective connectivity predicted persistent post-concussion symptoms and anxiety. Healthy controls had unique positive connectivity that mostly emerged from the inferior temporal lobes. In contrast, children with TBI had unique effective connectivity among orbitofrontal and parietal regions. These positive orbitofrontal-parietal DMN effective connectivity patterns also differed by TBI severity and were associated with persisting behavioural outcomes. Effective connectivity may be a sensitive neuroimaging marker of TBI severity as well as a predictor of chronic post-concussion symptoms and anxiety.

Adult age differences in remembering gain- and loss-related intentions

Motivational and emotional changes across adulthood have a profound impact on cognition. In this registered report, we conducted an experimental investigation of motivational influence on remembering intentions after a delay (prospective memory; PM) in younger, middle-aged, and older adults, using gain- and loss-framing manipulations. The present study examined for the first time whether motivational framing in a PM task has different effects on younger and older adults' PM performance (N = 180; age range: 18-85 years) in a controlled laboratory setting. Based on lifespan theories of motivation, we assumed that the prevention of losses becomes more relevant with increasing age: We expected that older adults show relatively higher PM performance in a task with loss-related consequences following PM failure than in a task in which successful PM leads to gains. The opposite pattern of performance was expected for younger adults. The findings suggest that the relevance of reward and positive gain-related consequences for successful remembering appears to decrease with age. As hypothesised, a motivational framing × age interaction indicated that age differences in memory performance were smaller with loss-related than gain-related consequences, supporting a loss-prevention view on motivated cognition.

Memory functioning 7 years after severe childhood traumatic brain injury: Results of the Traumatisme Grave de l'Enfant study

OBJECTIVE

To explore memory functioning 7 years after severe paediatric traumatic brain injury (TBI), associated factors, and relationships with other outcomes.

METHOD

Children aged 0-15 years (n = 65), consecutively admitted over a 3-year period in a single trauma centre, who survived after severe non-inflicted TBI, were included in a prospective longitudinal study. Memory assessments were performed 7 years post-injury using the Children's Memory Scale or the Wechsler Memory Scale (WMS IV), according to age. The General Memory Score (GMS-7) was the primary outcome.

RESULTS

Thirty-seven patients were available for assessment at 7 years post-injury. Mean GMS-7 was in the low average range (M = 84.9, SD = 12.1). Lower GMS-7 was significantly associated with markers of higher injury severity, such as length of coma. One year post-injury functional and disability outcomes explained 74% of the variance of GMS-7. Concurrent intellectual ability and type of ongoing education correlated strongly with GMS-7. Age at injury and parental education were not associated with memory outcome.

CONCLUSIONS

Memory functioning is variable but often strongly impaired several years after severe paediatric TBI, and is mostly related to injury severity, functional outcomes measured 1 year post-injury, and concomitant cognitive and educational outcomes. GMS-7 was lower at 7 years than one year post-injury, supporting the importance of long term follow-up.

Pediatric traumatic brain injury and abusive head trauma

Childhood traumatic brain injury (TBI) commonly occurs during brain development and can have direct, immediately observable neurologic, cognitive, and behavioral consequences. However, it can also disrupt subsequent brain development, and long-term outcomes are a combination of preinjury development and abilities, consequences of brain injury, as well as delayed impaired development of skills that were immature at the time of injury. There is a growing number of studies on mild TBI/sport-related concussions, describing initial symptoms and their evolution over time and providing guidelines for effective management of symptoms and return to activity/school/sports. Mild TBI usually does not lead to long-term cognitive or academic consequences, despite reports of behavioral/psychologic issues postinjury. Regarding moderate to severe TBI, injury to the brain is more severe, with evidence of a number of detrimental consequences in various domains. Patients can display neurologic impairments (e.g., motor deficits, signs of cerebellar disorder, posttraumatic epilepsy), medical problems (e.g., endocrine pituitary deficits, sleep-wake abnormalities), or sensory deficits (e.g., visual, olfactory deficits). The most commonly reported deficits are in the cognitive-behavioral field, which tend to be significantly disabling in the long-term, impacting the development of autonomy, socialization and academic achievement, participation, quality of life, and later, independence and ability to enter the workforce (e.g., intellectual deficits, slow processing speed, attention, memory, executive functions deficits, impulsivity, intolerance to frustration). A number of factors influence outcomes following pediatric TBI, including preinjury stage of development and abilities, brain injury severity, age at injury (with younger age at injury most often associated with worse outcomes), and a number of family/environment factors (e.g., parental education and occupation, family functioning, parenting style, warmth and responsiveness, access to rehabilitation and care). Interventions should identify and target these specific factors, given their major role in postinjury outcomes. Abusive head trauma (AHT) occurs in very young children (most often <6 months) and is a form of severe TBI, usually associated with delay before appropriate care is sought. Outcomes are systematically worse following AHT than following accidental TBI, even when controlling for age at injury and injury severity. Children with moderate to severe TBI and AHT usually require specific, coordinated, multidisciplinary, and long-term rehabilitation interventions and school adaptations, until transition to adult services. Interventions should be patient- and family-centered, focusing on specific goals, comprising education about TBI, and promoting optimal parenting, communication, and collaborative problem-solving.

Assessment of memory functioning over two years following severe childhood traumatic brain injury: results of the TGE cohort

The aims of this study were (1) to prospectively measure memory functioning following severe childhood Traumatic Brain Injury (TBI), and its evolution over 2 years; (2) to assess demographic and medical factors associated with memory function and recovery; (3) to explore relations between memory and other TBI outcomes. Methods: Children (aged 0-15 years; n= 65) consecutively admitted in a single trauma center over a 3-year period, who survived severe non-inflicted TBI, were included in a prospective longitudinal study. Memory was assessed in 38 children aged 5-15 years at injury, using the Children's Memory Scale at 3, 12, and 24 months post-injury. Results: Mean general memory score was low at 3 months (M = 90.2, SD = 20.3) but within the normal range at 12 and 24 months (M = 100.6, SD = 23.1 and M = 108.6, SD = 24.1, respectively), with high variability. Improvement was stronger for immediate visual memory than for other memory indices. Lower general memory score was associated with higher injury severity, lower intellectual ability and functional status, higher overall disability, and ongoing education. Conclusion: Memory functioning is highly variable following severe childhood TBI, related to injury severity and functional, cognitive and educational outcomes; improvement is significant during the first-year post-injury, but varies according to the type of memory.

Development and reliability of the Prospective Memory Assessment for Children & Youth (PROMACY): A preliminary study in a nonclinical sample

Prospective memory (PM), "remembering to remember," has been linked to important functional outcomes in adults. Studies of PM in children and adolescents would benefit from the development and validation of developmentally appropriate clinical measures with known psychometric properties. The Prospective Memory Assessment for Children & Youth (PROMACY), a performance-based measure of PM, was developed for the Pediatric HIV/AIDS Cohort Study Adolescent Master Protocol, Memory and Executive Functioning Substudy, and includes Summary, Time-, and Event-based scores derived from eight trials with an ongoing word search task. Fifty-four healthy perinatally HIV-exposed, uninfected children and youth, mean age 13 years, 54% female, 76% Black/non-Hispanic, and 61% impoverished were included in this psychometric analysis. PROMACY Summary Scores demonstrated low, but broadly acceptable internal consistency as measured by Cronbach's alpha and Spearman-Brown. Better PROMACY performance was associated with older age, but no other demographic factors. Generally medium-sized correlations were observed between the PROMACY Summary Score and standard clinical measures of retrospective memory, working memory, executive functions, and IQ. Findings from this preliminary psychometric study of nonclinical children and youth provide cautious support for the internal consistency and construct validity of PROMACY's Summary Score that awaits replication and extension in larger samples of healthy children, youth and clinical populations.

Negative Prospective Memory in Alzheimer's Disease: "Do Not Perform That Action"

Relatively to "standard" prospective memory, i.e., remembering to perform a future action, little is known about negative prospective memory, i.e., remembering not to perform a future action. This study investigated the latter ability in Alzheimer's disease (AD). AD participants and healthy older adults were asked to click on the keyboard or not to click on it when a cue word was encountered. Results showed more omissions (i.e., forgetting to click the keyboard when the instruction was to do so) in AD participants than in healthy older adults, suggesting a prospective memory deficit. Interestingly, more commissions (i.e., clicking the keyboard when the instruction was not to do so) were also observed in AD participants than in healthy older adults. Similar levels of commissions and omissions were observed in AD participants and in healthy older adults. Also, commissions and omissions were correlated with performance on an inhibition assessment task. Our findings reveal that AD is characterized by not only difficulty in the retrieval of recent information, but also difficulty to inhibit no-longer appropriate stimulus-response associations previously learned, suggesting a specific deficit of negative prospective memory in AD.

Prospective memory 7 years after severe childhood traumatic brain injury - the TGE 2 prospective longitudinal study

OBJECTIVE

To investigate the long-term outcome in prospective memory (PM), seven years after childhood severe traumatic brain injury (TBI), in a prospective longitudinal cohort.

PARTICIPANTS

76 young individuals (aged 7-22 years): 39 patients with a severe accidental TBI included prospectively seven years earlier, aged 0-15 years at injury, and 37 controls individually matched on age, gender and parental education.

MAIN OUTCOME MEASURES

Three novel short PM tasks varying in the delay, motivation and context (ecological versus paper and pencil task).

RESULTS

Individuals with severe TBI showed significantly poorer PM than matched controls in the two low-motivation PM tasks: (1) the ecological long-delay task consisting of sending a letter on a rainy day (p=0.047, odds ratio = 2.6); (2) the non-ecological short-delay task consisting of taking off post-its while identifying facial emotions (p=0.004, r=0.34). Differences in PM on the high motivation were not significant. PM is impaired several years post severe TBI.

Ecologically Valid Assessment of Prospective Memory for Task Planning and Execution by Adults With Acquired Brain Injury

PURPOSE

Individuals with acquired brain injury (ABI) often struggle due to inadequate planning and execution skills for completing nonroutine tasks. This study's purpose was to pilot ecologically valid procedures to assess planning for and execution of prospective daily activities.

METHOD

Participants included 9 adults with histories of severe ABI and 9 controls. Data collection included both prospective task planning and execution. First, participants created a plan for later execution of daily tasks in accordance with preestablished rules. Over the subsequent 10 days, participants independently attempted task completion. Differences within and between participant groups regarding planning and task performance were evaluated statistically and through examiner observation.

RESULTS

Participants with ABI implemented minimal planning strategies. They demonstrated highly variable performance and displayed substantially greater difficulty initiating and successfully executing tasks in adherence to rules than participants without ABI.

CONCLUSIONS

Evaluating planning strategies and execution of novel prospective tasks is a crucial but often neglected aspect of assessment following ABI. Implementing ecologically valid procedures to evaluate this aspect of functioning can reveal individual strengths and challenges and provide guidance for developing effective intervention programs. Examining potential roles played by planning and strategy execution provides critical assessment information relating to independent living.

Prospective memory in youth with perinatally-acquired HIV infection

Youth with perinatal HIV infection (PHIV) are at increased risk for neurocognitive impairment (NCI). Prospective memory (PM) is a complex neurocognitive function that has been shown to be impaired in adults with HIV disease and independently associated with poorer daily living skills, including medication nonadherence. The current study sought to determine the presence and extent of PM deficits in youth with PHIV. Participants included 173 youth with PHIV and 85 youth perinatally HIV-exposed but uninfected (PHEU), mean age 14.1 years, 75% black, 18% Hispanic. Among youth with PHIV, 26% had a past AIDS-defining condition (Centers for Disease Control and Prevention [CDC], Class C), 74% did not (non-C). Adjusted generalized estimating equation models were used to compare groups (PHIV/C, PHIV/non-C, and PHEU) on the Naturalistic Event-Based Prospective Memory Test (NEPT) and the Prospective Memory Assessment for Children & Youth (PROMACY). Secondarily, subgroups defined by HIV serostatus and global NCI were compared (PHIV/NCI, PHIV/non-NCI, PHEU). PHIV/C had significantly lower NEPT scores than PHEU, with decreases of 40% in mean scores, but did not differ from PHIV/non-C. PHIV/NCI had 11-32% lower PROMACY scores and 33% lower NEPT scores compared to PHIV/non-NCI (all p < .05); significantly, lower scores for PHIV/NCI versus PHEU also were observed for PROMACY and NEPT indices. Findings suggest a subset of youth with PHIV (those with a prior AIDS-defining diagnosis) is vulnerable to PM deficits. The extent to which PM deficits interfere with development and maintenance of independent living and health-related behaviors during transition to adulthood requires further study.

Ecological prospective memory assessment in children with acquired brain injury using the Children's Cooking Task

Prospective memory (PM) has been shown to be impaired in children with acquired brain injuries (ABI) and is a major concern for parents. Few studies have addressed this issue and most used tasks that are not ecologically valid. The aims of this study were (1) to explore if children who have sustained an ABI suffer PM impairment, measured both by the Children's Cooking task (CCT) PM score and using the 2 PM subtests of the Rivermead Behavioral Memory Test (RBMT), and (2) to explore if the CCT PM score is sensitive to developmental changes in PM in typically developing children and in children with ABI. Fifty-four children with ABI and 33 typically developing controls participated in the study. Children with ABI had significantly lower PM scores and poorer performance in the CCT than their typically developing peers. PM scores increased significantly with age, indicating developmental progress of PM performance.

Associations of Memory and Executive Functioning With Academic and Adaptive Functioning Among Youth With Perinatal HIV Exposure and/or Infection

BACKGROUND

Perinatally acquired HIV (PHIV) confers risk for neurocognitive impairment, which potentially affects school performance and functional independence of infected children. In this study, we examined the associations of 2 key neurocognitive domains, memory and executive function (EF), with academic and adaptive skills among youth with PHIV and perinatally HIV-exposed but uninfected (PHEU) youth.

METHODS

Participants ages 9 to <19 years enrolled in the Pediatric HIV/AIDS Cohort Study's Memory and Executive Functioning Study completed standardized measures of reading and math. The primary caregivers completed a standardized measure of their child's adaptive behavior. Participants with PHIV, those with (PHIV/C) and without (PHIV/non-C) a Centers for Disease Control and Prevention class C diagnosis, and PHEU participants were compared. Retrospective memory (RM), prospective memory (PM), and EF were evaluated relative to outcomes using general linear regression models adjusted for sociodemographic characteristics.

RESULTS

Of the participants (N = 258; mean age, 14.1 years), 46% were male, 75% were black, and 18% were Hispanic. Adjusted mean scores in math and adaptive behavior did not differ among the youth with PHIV/C (n = 45), those with PHIV/non-C (n = 128), and PHEU youth (n = 85). Youth with PHIV/C had lower adjusted mean reading scores than PHIV/non-C and PHEU youth (86.9 vs 93.8 [P = .02] and 93.2 [P = .04], respectively). There were positive associations of RM, PM, EF, and some sociodemographic characteristics with higher reading and math scores. Immediate and delayed verbal memory, delayed visual memory, PM, and some EF measures were positively associated with adaptive behavior.

CONCLUSIONS

Higher-order cognitive abilities such as memory and EF seem to play a key role in academic and adaptive capacities, regardless of a child's HIV status, and might serve as intervention targets for improving functional outcomes.

The Role of Extrinsic Rewards and Cue-Intention Association in Prospective Memory in Young Children

The current study examined, for the first time, the effect of cue-intention association, as well as the effects of promised extrinsic rewards, on prospective memory in young children, aged 5-years-old (n = 39) and 7-years-old (n = 40). Children were asked to name pictures for a toy mole, whilst also having to remember to respond differently to certain target pictures (prospective memory task). The level to which the target picture was associated with the intention was manipulated across two conditions (low- or high-association) for all participants, whilst half of the participants were promised a reward for good prospective memory performance. Results showed a main effect of age, with the 7-year-olds outperforming the 5-year-olds. Furthermore, there was a main effect of reward, with those promised a reward performing better than those who were not. No effect was found for cue-association, with the participants of both age groups performing equally well in both association conditions. No significant interactions were found between any of the variables. The potentially important role of reward in young children's everyday prospective memory tasks, and possible reasons for the lack of a reflexive-associative effect, are discussed.

Toward an understanding of motivational influences on prospective memory using value-added intentions

This study examined value-added intentions by manipulating the cognitive frame associated with monetary contingencies for detecting prospective memory (PM) cues. We associated a loss-frame with a monetary punishment for failing to respond to cues and a gain-frame with a monetary reward for remembering to respond to cues and compared those frames to a no-frame control condition with no contingency linked to performance. Across two experiments, we find increased PM performance for participants in the loss-frame (Experiments 1 and 2) and in the gain-frame (Experiment 2) conditions relative to the no-frame condition. This value-related improvement in PM was not accompanied by a significant increase in cue monitoring as measured by intention-induced interference to an ongoing task and recognition memory for ongoing-task items. The few previous studies investigating motivational PM showed mixed results regarding whether PM improves due to incentives or not. Our results provide further evidence that, under some experimental conditions, PM improves with rewards and that the benefit generalizes to penalizing performance. The results have both practical implications and theoretical implications for motivation models of PM.

Effect of motivation on academic fluency performance in survivors of pediatric medulloblastoma

It has been proposed previously that extrinsic motivation may enable survivors of childhood medulloblastoma to significantly improve aspects of neurocognitive performance. In healthy populations, enhanced motivation has been shown to promote academic fluency, a domain likely more relevant to the educational outcomes of pediatric medulloblastoma survivors than academic skill development. The present study investigates the effect of enhanced extrinsic motivation on fluent (i.e., accurate and efficient) academic performance in pediatric medulloblastoma survivors. Participants were 36 children, ages 7-18, who had completed treatment for medulloblastoma. Participants completed a neuropsychological battery that included administration of equivalent tasks on Forms A and B of the Woodcock-Johnson III Tests of Achievement. Half were randomly assigned to an incentive condition prior to the administration of Form B. Provision of a performance-based incentive resulted in statistically significant improvement, but not normalization of function, in performance on measures of academic fluency. No demographic, treatment-related, academic, neuropsychological, or self-perception variables predicted response to incentive. Findings suggest that academic performance of survivors may significantly improve under highly motivating conditions. In addition to implications for educational services, this finding raises the novel possibility that decreased motivation represents an inherent neuropsychological deficit in this population and provides a rationale for further investigation of factors affecting individual differences in motivational processes. Further, by examining effort in a context where effort is not inherently suspect, present findings also significantly contribute to the debate regarding the effects of effort and motivation on neuropsychological performance.

Memory outcomes following cognitive interventions in children with neurological deficits: A review with a focus on under-studied populations

Given the primary role of memory in children's learning and well-being, the aim of this review was to examine the outcomes of memory remediation interventions in children with neurological deficits as a function of the affected memory system and intervention method. Fifty-seven studies that evaluated the outcome of memory interventions in children were identified. Thirty-four studies met the inclusion criteria, and were included in a systematic review. Diverse rehabilitation methods for improving explicit and implicit memory in children were reviewed. The analysis indicates that teaching restoration strategies may improve, and result in the generalisation of, semantic memory and working memory performance in children older than 7 years with mild to moderate memory deficits. Factors such as longer protocols, emotional support, and personal feedback contribute to intervention efficacy. In addition, the use of compensation aids seems to be highly effective in prospective memory tasks. Finally, the review unveiled a lack of studies with young children and the absence of group interventions. These findings point to the importance of future evidence-based intervention protocols in these areas.

Task importance affects event-based prospective memory performance in adults with HIV-associated neurocognitive disorders and HIV-infected young adults with problematic substance use

Two experiments were conducted to examine the effects of task importance on event-based prospective memory (PM) in separate samples of adults with HIV-associated neurocognitive disorders (HAND) and HIV-infected young adults with substance use disorders (SUD). All participants completed three conditions of an ongoing lexical decision task: (1) without PM task requirements; (2) with PM task requirements that emphasized the importance of the ongoing task; and (3) with PM task requirements that emphasized the importance of the PM task. In both experiments, all HIV+ groups showed the expected increase in response costs to the ongoing task when the PM task's importance was emphasized. In Experiment 1, individuals with HAND showed significantly lower PM accuracy as compared to HIV+ subjects without HAND when the importance of the ongoing task was emphasized, but improved significantly and no longer differed from HIV+ subjects without HAND when the PM task was emphasized. A similar pattern of findings emerged in Experiment 2, whereby HIV+ young adults with SUD (especially cannabis) showed significant improvements in PM accuracy when the PM task was emphasized. Findings suggest that both HAND and SUD may increase the amount of cognitive attentional resources that need to be allocated to support PM performance in persons living with HIV infection.

How important is importance for prospective memory? A review

Forgetting to carry out an intention as planned can have serious consequences in everyday life. People sometimes even forget intentions that they consider as very important. Here, we review the literature on the impact of importance on prospective memory performance. We highlight different methods used to manipulate the importance of a prospective memory task such as providing rewards, importance relative to other ongoing activities, absolute importance, and providing social motives. Moreover, we address the relationship between importance and other factors known to affect prospective memory and ongoing task performance such as type of prospective memory task (time-, event-, or activity-based), cognitive loads, and processing overlaps. Finally, we provide a connection to motivation, we summarize the effects of task importance and we identify important venues for future research.

Event-based prospective memory in the rat

People plan to act in the future when an appropriate event occurs, a capacity known as event-based prospective memory. Prospective memory involves forming a representation of a planned future action, subsequently inactivating the representation, and ultimately reactivating it at an appropriate point in the future. Recent studies suggest that monkeys, chimpanzees, and rats display elements of prospective memory, but it is uncertain if the full sequence (activation-inactivation-reactivation) that occurs in humans also occurs in nonhumans. Here, we asked if rats exhibit event-based prospective memory. Rats completed an ongoing temporal-discrimination task while waiting for a large meal. To promote the use of event-based prospective memory, we created an event (tone pulses) that provided information that the meal could be obtained soon. Event-based prospective memory was suggested by the dramatic decline in ongoing-task performance after the event, with excellent performance at other times. To document that the event initiated memory activation, we arranged for the event to occur at novel times. Finally, multiple, repeated presentations of the event on the same day demonstrate that rats inactivate and reactivate the memory representation in an on-demand, event-based fashion. Development of an animal model of prospective memory may be valuable to probe the biological underpinnings of memory disorders.

Remembering the past and planning for the future in rats

A growing body of research suggests that rats represent and remember specific earlier events from the past. An important criterion for validating a rodent model of episodic memory is to establish that the content of the representation is about a specific event in the past rather than vague information about remoteness. Recent evidence suggests that rats may also represent events that are anticipated to occur in the future. An important capacity afforded by a representation of the future is the ability to plan for the occurrence of a future event. However, relatively little is known about the content of represented future events and the cognitive mechanisms that may support planning. This article reviews evidence that rats remember specific earlier events from the past, represent events that are anticipated to occur in the future, and develops criteria for validating a rodent model of future planning. These criteria include representing a specific time in the future, the ability to temporarily disengage from a plan and reactivate the plan at an appropriate time in the future, and flexibility to deploy a plan in novel conditions.

Prospective cognition in rats

Efforts to develop animal models of memory are critical for understanding the neural substrate of memory. Memory is essential for daily life and enables information to be stored and retrieved after seconds to years. The ability to remember episodes from the past is thought to be related to the ability to plan for the future. Here we focus on a particular aspect of prospective cognition, namely the ability to remember to take action when a future scenario occurs. This review focuses on a recently developed method to evaluate prospective memory in the rat. Available evidence suggests that rats remember to take action in the future, but little is known about the temporal specificity of such memories or about the flexibility and limitations of prospective memories. Recent studies that suggest that rats remember a specific past episode are reviewed to underscore potential approaches that may be used to explore the range and limits of prospective cognition. The review highlights some directions to explore, including the temporal specificity of prospective cognition, the range of flexibility or creativity within prospective cognition, and the constraints imposed by multiple motivational systems.

Monetary incentive effects on event-based prospective memory three months after traumatic brain injury in children

Information regarding the remediation of event-based prospective memory (EB-PM) impairments following pediatric traumatic brain injury (TBI) is scarce. Addressing this, two levels of monetary incentives were used to improve EB-PM in children ages 7 to 16 years with orthopedic injuries (OI, n = 51), or moderate (n = 25) and severe (n = 39) TBI at approximately 3 months postinjury. The EB-PM task consisted of the child giving a specific verbal response to a verbal cue from the examiner while performing a battery of neuropsychological measures (ongoing task). Significant effects were found for age-at-test, motivation condition, period, and group. Within-group analyses indicated that OI and moderate TBI groups performed significantly better under the high- than under the low-incentive condition, but the severe TBI group demonstrated no significant improvement. These results indicate that EB-PM can be significantly improved at 3 months postinjury in children with moderate, but not severe, TBI.

Prospective memory in the rat

The content of prospective memory is comprised of representations of an action to perform in the future. When people form prospective memories, they temporarily put the memory representation in an inactive state while engaging in other activities, and then activate the representation in the future. Ultimately, successful activation of the memory representation yields an action at an appropriate, but temporally distant, time. A hallmark of prospective memory is that activation of the memory representation has a deleterious effect on current ongoing activity. Recent evidence suggests that scrub jays and non-human primates, but not other species, are capable of future planning. We hypothesized that prospective memory produces a selective deficit in performance at the time when rats access a memory representation but not when the memory representation is inactive. Rats were trained in a temporal bisection task (90 min/day). Immediately after the bisection task, half of the rats received an 8-g meal (meal group) and the other rats received no additional food (no-meal group). Sensitivity to time in the bisection task was reduced as the 90-min interval elapsed for the meal group but not for the no-meal group. This time-based prospective-memory effect was not based on response competition, an attentional limit, anticipatory contrast, or fatigue. Our results suggest that rats form prospective memories, which produces a negative side effect on ongoing activity.

Traumatic brain injury and secondary attention-deficit/hyperactivity disorder in children and adolescents: the effect of reward on inhibitory control

Poor inhibitory control and abnormalities in responding to rewards are characteristic of the developmental or primary form of attention-deficit/hyperactivity disorder (P-ADHD). A secondary form of ADHD (S-ADHD) may occur as a consequence of childhood traumatic brain injury (TBI), but the similarities and differences between these two forms of ADHD have not been well characterized. To address these issues, we studied two inhibitory control tasks under different reward conditions in four groups of children and adolescents: TBI who did not exhibit S-ADHD, TBI who did exhibit S-ADHD, P-ADHD, and healthy controls. Participants with TBI exhibited poor cancellation inhibition relative to controls. Although reward facilitated both cancellation and restraint inhibition similarly across groups, poor performance persisted in the P-ADHD group, and participants with S-ADHD exhibited a selective deficit in cancellation inhibition.

Diffusion tensor imaging of incentive effects in prospective memory after pediatric traumatic brain injury

Few studies exist investigating the brain-behavior relations of event-based prospective memory (EB-PM) impairments following traumatic brain injury (TBI). To address this, children with moderate-to-severe TBI performed an EB-PM test with two motivational enhancement conditions and underwent concurrent diffusion tensor imaging (DTI) at 3 months post-injury. Children with orthopedic injuries (OI; n=37) or moderate-to-severe TBI (n=40) were contrasted. Significant group differences were found for fractional anisotropy (FA) and apparent diffusion coefficient for orbitofrontal white matter (WM), cingulum bundles, and uncinate fasciculi. The FA of these WM structures in children with TBI significantly correlated with EB-PM performance in the high, but not the low motivation condition. Regression analyses within the TBI group indicated that the FA of the left cingulum bundle (p=0.003), left orbitofrontal WM (p<0.02), and left (p<0.02) and right (p<0.008) uncinate fasciculi significantly predicted EB-PM performance in the high motivation condition. We infer that the cingulum bundles, orbitofrontal WM, and uncinate fasciculi are important WM structures mediating motivation-based EB-PM responses following moderate-to-severe TBI in children.

Prospective memory in patients with closed head injury: a review

This paper aimed to review the limited, but growing literature on prospective memory (PM) following closed head injury (CHI). Search of two commonly used databases yielded studies that could be classified as: self- or other-report of PM deficits; behavioral PM measures in adults with CHI, behavioral PM measures in children and adolescents with CHI, and treatment of PM in adults with CHI. The methodology and findings of these studies were critically reviewed and discussed. Because of the small number of studies, meta-analysis was only conducted for studies that used behavioral PM measures in adults to integrate findings. PM deficits were found to be commonly reported by patients with CHI and their significant others and they could be identified using behavioral measures in adults, children and adolescents with CHI. However, more work is needed to clarify the nature and mechanisms of these deficits. Although some promising results have been reported by studies that evaluated PM treatment, most studies lack tight experimental control and used only a small number of participants. The paper concluded with some suggestions for future research.

Patterns of cortical thinning in relation to event-based prospective memory performance three months after moderate to severe traumatic brain injury in children

While event-based prospective memory (EB-PM) tasks are a familiar part of daily life for children, currently no data exists concerning the relation between EB-PM performance and brain volumetrics after traumatic brain injury (TBI). This study investigated EB-PM in children (7 to 17 years) with moderate to severe TBI or orthopedic injuries. Participants performed an EB-PM task and concurrently underwent neuroimaging at three months postinjury. Surface reconstruction and cortical thickness analysis were performed using FreeSurfer software. Cortical thickness was significantly correlated with EB-PM (adjusting for age). Significant thinning in the left (dorsolateral and inferior prefrontal cortex, anterior and posterior cingulate, temporal lobe, fusiform, and parahippocampal gyri), and right hemispheres (dorsolateral, inferior, and medial prefrontal cortex, cingulate, and temporal lobe) correlated positively and significantly with EB-PM performance; findings are comparable to those of functional neuroimaging and lesion studies of EB-PM.

Event-based prospective memory in children with sickle cell disease: effect of cue distinctiveness

Event-based prospective memory (EB-PM) is the formation of an intention and remembering to perform it in response to a specific event. Currently, EB-PM performance in children with sickle cell disease (SCD) is unknown. In this study, we designed a computer-based task of EB-PM; No-Stroke, Silent-Infarct, and Overt-Stroke groups performed significantly below the demographically similar control group without SCD. Cue distinctiveness was varied to determine if EB-PM could be improved. All groups, with the exception of the Overt-Stroke group, performed significantly better with a perceptually distinctive cue. Overall, these results suggest that EB-PM can be improved significantly in many children with SCD.

Event-based prospective memory performance during subacute recovery following moderate to severe traumatic brain injury in children: Effects of monetary incentives

There are very few studies investigating remediation of event-based prospective memory (EB-PM) impairments following traumatic brain injury (TBI). To address this, we used 2 levels of motivational enhancement (dollars vs. pennies) to improve EB-PM in children with moderate to severe TBI in the subacute recovery phase. Children with orthopedic injuries (OI; n = 61), moderate (n = 28), or severe (n = 30) TBI were compared. Significant effects included Group x Motivation Condition (F(2, 115) = 3.73, p < .03). The OI (p < .002) and moderate TBI (p < .03) groups performed significantly better under the high- versus low-incentive condition; however, the severe TBI group failed to demonstrate improvement (p = .38). EB-PM performance was better in adolescents compared to younger children (p < .02). These results suggest that EB-PM can be significantly improved in the subacute phase with this level of monetary incentives in children with moderate, but not severe, TBI. Other strategies to improve EB-PM in these children at a similar point in recovery remain to be identified and evaluated.