Preliminary evidence for a relationship between prospective memory and PTSD symptoms in the general population

IntroductionPTSD sufferers often have problems with remembering the past, but do they also have trouble remembering tasks to be completed in the future? We argue characteristics of PTSD—such as negative appraisals and maladaptive strategies—might contribute to biased reporting of prospective memory failures among PTSD sufferers—or people with severe PTSD symptoms—within a general population.MethodsMechanical Turk participants completed a questionnaire battery measuring self-report prospective memory, PTSD symptoms, negative appraisals and maladaptive strategies (e.g., suppression), and depression, anxiety and stress symptoms.ResultsPTSD symptom severity positively correlated with self-report prospective memory failures (rs = .42–49). PTSD symptoms affected self-report prospective memory via their influence on negative appraisals and maladaptive strategies.LimitationsOur findings rely on self-report, therefore we do not know if this relationship generalizes to objective prospective memory tasks.ConclusionsOur data provide preliminary evidence for a relationship between PTSD symptomatology and subjective prospective memory in the general population and suggest that the negative appraisals and maladaptive strategies that commonly accompany PTSD might underpin this relationship.     

Reflections on Conversations and Memory

The study of memory and remembering has traditionally either stripped meaning away from acts of remembering to reveal the “raw material of memory” or explored how meaning guides the reconstruction of the past. In reflecting on the contributions to this topic, there appears to be an emerging “third‐way,” which holds that there is an inextricable relation between conversations and remembering. The articles in this volume exemplify how conversing is often an act of remembering and represent approaches to memory that might not otherwise be taken if one were to study memory as a within‐individual phenomenon. The implications of this approach are far‐ranging and present the opportunity to pose new questions about the nature of remembering as it unfolds in conversation. The contributing articles have expanded the scope of what memory researchers can study by adopting a relatively straightforward assumption about the sociality of remembering and the role of the conversation in the social process.     

I cannot remember,but I know my past events: remembering and knowing in a patient with amnesic syndrome

Case Y.K. has severe anterograde amnesia and a selective loss of specific personal episodes in his remote memories (Hirano & Noguchi, 1998). In this paper, we attempted to analyze remembering (R) and knowing (K) responses, that is, the relationship between autobiographical remembering and remembering accompanied by subjective experience. Although the rate of R responses was significantly higher than that of K responses in control subjects, Y.K.'s R responses were rare in all subtypes of remote memories. Based on these results, we conclude that Y.K.'s memories on autobiographical incident task were not based on episodic memory but rather on semantic memory. Thus, the autobiographical incidents he could recall were not episodic memory, and his semantic memory made him recall information as fact rather than episode.     

Debunking myths about trauma and memory.

How trauma victims remember--or forget--their most horrific experiences lies at the heart of the most bitter controversy in psychiatry and psychology in recent times. Whereas experts maintain that traumatic events--those experienced as overwhelmingly terrifying at the time of their occurrence--are remembered all too well, traumatic amnesia theorists disagree. Although these theorists acknowledge that trauma is often seemingly engraved on memory, they nevertheless maintain that a significant minority of survivors are incapable of remembering their trauma, thanks to mechanisms of either dissociation or repression. Unfortunately, the evidence they adduce in support of the concept of traumatic dissociative amnesia fails to support their claims. The purpose of this review is to dispel confusions and debunk myths regarding trauma and memory.     

Features of Successful and Unsuccessful Collaborative Memory Conversations in Long‐Married Couples

While we often engage in conversational reminiscing with loved ones, the effects of these conversations on our memory performance remain poorly understood. On the one hand, Wegner's transactive memory theory predicts that intimate groups experience benefits from remembering together. On the other hand, research on collaborative recall has shown costs of shared remembering in groups of strangers—at least in terms of number of items recalled—and even in intimate groups there is heterogeneity in outcomes. In the current research, we studied the effects of particular communicative features in determining the outcomes of collaborative recall in intimate groups. We tested 39 older, long‐married couples. They completed a non‐personal recall task (name all the countries in Europe) and a personal recall task (name all your mutual friends), both separately and together. When they collaborated, we recorded their conversation. We coded for specific “communication variables” and obtained measures of “conversational style.” Overall, we found two clusters of communication variables positively associated with collaborative success: (a) cuing each other, responding to cues, and repeating each other; and (b) making positive statements about memory performance and persisting with the task. A negative cluster of behaviors—correcting each other, having uneven expertise, and strategy disagreements—was associated with less interactive, more “monologue” style of collaboration, but not with overall recall performance. We discuss our results in terms of the importance of different conversational processes in driving the heterogeneous outcomes of group remembering in intimate groups, suggesting that a focus on recall output alone limits our understanding of conversational remembering.     

Imagining the future: Evidence for a hippocampal contribution to constructive processing

Imagining future events and remembering past events rely on a common core network, but several regions within this network—including the hippocampus—show increased activity for imagining future events compared to remembering past events. It remains unclear whether this hippocampal activity reflects processes related to the demands of constructing details retrieved across disparate episodic memories into coherent imaginary events, encoding these events into memory, novelty detection, or some combination of these processes. We manipulated the degree of constructive processing by comparing activity associated with the initial construction of an imagined scenario with the re‐construction of an imagined scenario (imagine vs. re‐imagine). After accounting for effects of novelty and subsequent memory, we found that a region in the hippocampus was preferentially activated for newly constructed imagined events compared with re‐imagined events. Our results suggest that the hippocampus may support several distinct but related processes that are critical for imagining future events, and they also indicate that a particular region within posterior hippocampus may uniquely contribute to the construction of imagined future events. © 2013 Wiley Periodicals, Inc.     

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.     

Success and Failure in Memory Training Following a Cerebral Vascular Accident

This paper describes the treatment offered to a 51 year old man suffering from a severe memory deficit which followed a bilateral stroke. The aims of treatment were: (a) to improve memory generally and (b) to find ways to help him retain new information in 4 specific problem areas namely remembering: (i) his daily timetable, (ii) people's names, (iii) a shopping list, and (iv) short routes. A multiple baseline procedure was used to investigate this. At the end of the treatment period only slight improvement was found in his memory generally, although on a motor memory task he improved steadily throughout. Strategies were found to help him with 3 of the 4 specific problems. The fourth — remembering short routes — was resistant to all the strategies tried. The paper discusses the effectiveness of treatment, the nature of the lesion and how this case contributes towards our understanding of human memory and forgetting.     

Elaborated spaced-retrieval and prospective memory in mild Alzheimer's disease

Prospective memory, or the timely remembering of a planned action, is conceptualised as a cognitive process demanding episodic memory and executive attention. Impairments in these skills are characteristic of the cognitive decline in early Alzheimer's disease, providing an expectation of prominent prospective memory difficulties in this population, and yet surprisingly, memory performance in early Alzheimer's disease has rarely been evaluated within a prospective memory framework. In a preliminary study we demonstrated that older adults with early Alzheimer's disease (n=14), as compared to healthy older adults (n=14), were significantly impaired in a simple experimental paradigm of prospective remembering (a text-reading task). In a subsequent intervention study, we investigated the efficacy of spaced-retrieval for improving the prospective remembering performance of older adults with early Alzheimer's disease (n=16) compared to healthy older adults (n=16) under two learning conditions: a spaced-retrieval technique alone or spaced-retrieval combined with elaborated encoding of task. The majority of the Alzheimer's disease group (63%) demonstrated benefit in prospective remembering in the combined condition as compared to spaced-retrieval alone. Participants with Alzheimer's disease who demonstrated better executive attention (Trail Making- set-shifting) and/or better retrospective memory (Hopkins Verbal Learning Test-Revised- recognition) were more successful in the combined learning condition.     

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.     

Memory amplification for trauma: Investigating the role of analogue PTSD symptoms in the laboratory

Victims of trauma often remember their experience as being more traumatic later, compared to immediately after, the event took place. This finding—the “memory amplification effect”—is associated with increased re-experiencing symptoms. However, the effect has been found almost exclusively in field-based studies. We examined whether the effect could be replicated in the laboratory. In two studies, we exposed participants to negative photographs and assessed their memory for the photographs and analogue PTSD symptoms on two occasions. In Study 1, analogue symptoms at follow-up were positively associated with remembering more negative photos over time. In Study 2, we focused on “memory amplifiers”: people whose memory of the photos amplified over time. Consistent with field research, analogue re-experiencing symptoms were associated with memory amplification. Overall, our findings confirm that analogue PTSD symptoms are also associated with an amplified memory for a trauma analogue.     

Electrophysiological correlates of forming memories for faces, names, and face-name associations

The ability to put a name to a face is a vital aspect of human interaction, but many people find this extremely difficult, especially after being introduced to someone for the first time. Creating enduring associations between arbitrary stimuli in this manner is also a prime example of what patients with amnesia find most difficult. To help develop a better understanding of this type of memory, we sought to obtain measures of the neural events responsible for successfully forming a new face-name association. We used event-related potentials (ERPs) extracted from high-density scalp EEG recordings in order to compare (1) memory for faces, (2) memory for names, and (3) memory for face-name associations. Each visual face appeared simultaneously with a unique spoken name. Signals observed 200-800 ms after the onset of face-name pairs predicted subsequent memory for faces, names, or face-name associations. Difference potentials observed as a function of subsequent memory performance were not identical for these three memory tests, nor were potentials predicting associative memory equivalent to the sum of potentials predicting item memory, suggesting that different neural events at the time of encoding are relevant for these distinct aspects of remembering people.     

Episodic Memory and Remembering in Adults with Asperger Syndrome

A group of adults with Asperger syndrome and an IQ-matched control group were compared in remember versus know recognition memory. Word frequency was also manipulated. Both groups showed superior recognition for low-frequency compared with high-frequency words, and in both groups this word frequency effect occurred in remembering, not in knowing. Nor did overall recognition differ between the two groups. However, recognition in the Asperger group was associated with less remembering, and more knowing, than in the control group. Since remembering reflects autonoetic consciousness, which is the hallmark of an episodic memory system, these results show that episodic memory is moderately impaired in individuals with Asperger syndrome even when overall recognition performance is not.     

Elaborated spaced-retrieval and prospective memory in mild Alzheimer's disease

Prospective memory, or the timely remembering of a planned action, is conceptualised as a cognitive process demanding episodic memory and executive attention. Impairments in these skills are characteristic of the cognitive decline in early Alzheimer's disease, providing an expectation of prominent prospective memory difficulties in this population, and yet surprisingly, memory performance in early Alzheimer's disease has rarely been evaluated within a prospective memory framework. In a preliminary study we demonstrated that older adults with early Alzheimer's disease (n = 14), as compared to healthy older adults (n = 14), were significantly impaired in a simple experimental paradigm of prospective remembering (a text-reading task). In a subsequent intervention study, we investigated the efficacy of spaced-retrieval for improving the prospective remembering performance of older adults with early Alzheimer's disease (n = 16) compared to healthy older adults (n = 16) under two learning conditions: a spaced-retrieval technique alone or spaced-retrieval combined with elaborated encoding of task. The majority of the Alzheimer's disease group (63%) demonstrated benefit in prospective remembering in the combined condition as compared to spaced-retrieval alone. Participants with Alzheimer's disease who demonstrated better executive attention (Trail Making – set-shifting) and/or better retrospective memory (Hopkins Verbal Learning Test–Revised – recognition) were more successful in the combined learning condition.     

Early episodic memory impairments in Alzheimer's disease

Patients with Alzheimer's disease (AD) show early episodic memory impairments. Such deficits reflect specific impairments affecting one or several stages of encoding, storage and retrieval processes. However, AD patients not only have great difficulty retrieving memories and information but also suffer from distortions of memory, as intrusions and false recognitions. Intrusions can be defined as the unintentional recall of inappropriate information in a laboratory-learning tasks such as word-list recall and story recall. False recognition refers to the erroneous recognition of information that was not previously presented. The first objective of this review is to present studies from the literature that allowed a better understanding of the nature of episodic memory deficits in AD, and to examine recent research on false memories. The second part of this review is aimed at presenting recent research conducted on prospective memory (PM) in Alzheimer's disease. Prospective memory situations involve forming intentions and then realizing those intentions at some appropriate time in the future. Everyday examples of prospective memory include remembering to buy bread on the way home from work, remembering to give friends a message upon next encountering them, and remembering to take medication. Patients suffering from AD show difficulties in performing prospective tasks in daily life, according to the complaints of their care givers, and these difficulties are massively present at the first stages of the disease. Nevertheless, very few studies have been dedicated to this subject, although the evaluation of PM could be helpful for the early diagnosis of AD.     

Age-related declines in prospective memory: behavioral and electrophysiological evidence

Prospective remembering reflects the ability of an individual to form and later realize intentions that must be delayed over minutes, hours, or days. A substantial body of literature, primarily based upon the findings of behavioral studies, indicates that there are robust declines in the efficiency of prospective remembering in later adulthood. However, the cognitive and neural mechanisms mediating age-related deficits in prospective remembering are not well understood. In this review we consider evidence from recent behavioral and electrophysiological studies indicating that decreases in the efficiency of prospective memory in older adults results from age-related differences in those neural mechanisms supporting the encoding of intentions into memory and the detection of prospective memory cues in the environment.     

Autobiographical memory, the sense of recollection and executive functions after severe traumatic brain injury

Residual disorders of autobiographical memory long after trauma resulting from head injury are rarely assessed, even though they may affect social adjustment and the resumption of daily life. We conducted a thorough study of autobiographical memory in severe traumatic brain injury (TBI) patients, examined at least one year post-trauma. Twenty-five patients were submitted to a novel and controlled autobiographical procedure specially designed to measure episodic memories (i.e., unique, specific in time and space, and detailed) from their entire life span with two kinds of self-remembering experience. The ability to mentally travel back through time and re-experience the source of acquisition, i.e. autonoetic consciousness, was assessed via the "Remember/Know" paradigm and a checking procedure of sense of remembering. Self-perspective in visual imagery, which is also critically involved in episodic recollection, was assessed by the "Field/Observer perspective" paradigm. In addition, the patients underwent a battery of standardized neuropsychological tests to assess episodic and semantic memory, orientation and executive functions. The results showed that the patients, compared with healthy controls, were significantly impaired in recalling episodic autobiographical memories. This impairment was not related to the life period tested or the patients' ages nor the intellectual impairment. Deficits involved disturbances in sense of remembering, visual imagery self-perspective and recollection of spatiotemporal details. Stepwise-regression analyses carried out in the TBI patients revealed a significant relationship between an abnormal sense of remembering and executive dysfunction covering both anterograde and retrograde components. The novel assessment used in this study provides the first detailed evidence of a more fine-grained deficit of autobiographical memory in TBI patients. Indeed, the results suggest that these patients, long after trauma, present autonoetic consciousness and self-perspective disorders, which include sense of identity (the self) as a continuous entity across time, probably related to frontal dysfunction.     

Adolescent methylmercury exposure alters short-term remembering,but not sustained attention,in male Long-Evans rats

Methylmercury is an environmental neurotoxicant found in fish that produces behavioral deficits following early developmental exposure. The impact of adolescent exposure to this developmental neurotoxicant is only recently being explored in animal models. Here, short-term memory and sustained attention were examined using a rodent model of adolescent methylmercury exposure. Rats were exposed to 0, 0.5, or 5 ppm methylmercury throughout the adolescent period and tested on a two-choice visual signal detection task in adulthood. Methylmercury improved short-term remembering in this procedure but the dose-effect curve was nonmonotonic, as has been reported previously: effects on memory were observed in animals exposed to 0.5 ppm methylmercury, but not 5 ppm. Methylmercury did not significantly alter sustained attention, which is in contrast to effects following gestational exposure in human populations. The results may suggest that attention is not involved with previously reported effects of methylmercury during adolescence, but certain procedural issues remain unresolved.     

Electrophysiological measures of familiarity memory.

Event-related potentials are a valuable tool for the study of human memory function. This selective review provides a brief introduction in models of recognition memory and then describes how ERPs can be used to investigate familiarity memory, an acontextual form of remembering that can be distinguished from the recollection of detailed information of prior events. ERP studies on the mid-frontal old/new effect, the putative electrophysiological correlate of familiarity memory are reviewed. It will be illustrated how familiarity memory is reflected in this effect, how it can electrophysiologically be dissociated from other forms of memory and which brain systems mediate this form of remembering. Recent studies will be reviewed that illustrate that familiarity is not only restricted to single items but can also support the retrieval of associative information.     

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.