Collaborative memory intervention in dementia: Caregiver participation matters

The aim of the study was to examine the effectiveness of a collaborative memory intervention for persons with dementia and their spousal caregivers, where the couple acquired and practised memory supportive strategies (spaced-retrieval and hierarchical cuing) to learn a face–name association and to set a table for coffee/tea. The collaborative intervention was compared to an individual intervention where the person with dementia received the same training but without the participating caregiver and to a control group of couples receiving no training. The results showed that following collaborative intervention recall performance in two collaborative tasks became more equally shared between the spouses, reflected in a decrease in recall for the caregiver and in an increase in recall for the spouse with dementia between pre- and post-test; whereas for the other two groups the caregivers dominated collaborative recall both at pre- and post-test. The results also showed that the persons with dementia in the collaborative group improved their individually assessed episodic memory performance as compared to the persons with dementia in the other two groups. Finally, training had no effects on episodic memory, perceived burden or depressive symptoms for the caregivers. These results suggest that the active participation of the caregiver matters in cognitive dementia rehabilitation.     

Recalling the firedog: Individual differences in associative memory for unitized and nonunitized associations among older adults

Memory deficits in aging are characterized by impaired hippocampus‐mediated relational binding—the formation of links between items in memory. By reducing reliance on relational binding, unitization of two items into one concept enhances associative recognition among older adults. Can a similar enhancement be obtained when probing memory with recall? This question has yet to be examined, because recall has been assumed to rely predominantly on relational binding. Inspired by recent evidence challenging this assumption, we investigated individual differences in older adults' recall of unitized and nonunitized associations. Compared with successfully aging individuals, older adults with mild memory deficits, typically mediated by the hippocampus, were impaired in recall of paired‐associates in a task which relies on relational binding (study: “PLAY–TUNNEL”; test: PLAY–T?). In stark contrast, the two groups showed similar performance when items were unitized into a novel compound word (study: “LOVEGIGGLE”; test: LOVEG?). Thus, boosting nonrelational aspects of recall enhances associative memory among aging individuals with subtle memory impairments to comparable levels as successfully aging older adults.     

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.     

A Case of Unusual Autobiographical Remembering

This report describes AJ, a woman whose remembering dominates her life. Her memory is “nonstop, uncontrollable, and automatic.” AJ spends an excessive amount of time recalling her personal past with considerable accuracy and reliability. If given a date, she can tell you what she was doing and what day of the week it fell on. She differs from other cases of superior memory who use practiced mnemonics to remember vast amounts of personally irrelevant information. We propose the name hyperthymestic syndrome, from the Greek word thymesis meaning remembering, and that AJ is the first reported case.     

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.     

Effect of a synesthete's photisms on name recall

A multilingual, colored-letter synesthete professor (MLS), 9 nonsynesthete multilingual professors and 4 nonsynesthete art professors learned 30 names of individuals (first and last name pairs) in three trials. They recalled the names after each trial and six months later, as well as performed cued recall trials initially and after six months. As hypothesized, MLS recalled significantly more names than control groups on all free recall tests (except after the first trial) and on cued recall tests. In addition, MLS gave qualitatively different reasons for remembering names than any individual control participant. MLS gave mostly color reasons for remembering the names, whereas nonsynesthetes gave reasons based on familiarity or language or art knowledge. Results on standardized memory tests showed that MLS had average performance on non-language visual memory tests (the Benton Visual Retention Test-Revised--BURT-R, and the Rey-Osterrieth Complex Figure Test--CFT), but had superior memory performance on a verbal test consisting of lists of nouns (Rey Auditory-Verbal Learning Test--RAVLT). MLS's synesthesia seems to aid memory for visually or auditorily presented language stimuli (names and nouns), but not for non-language visual stimuli (simple and complex figures).     

The Influence of the Stroop Interference Effect on an Event-based Prospective Memory Task in Alzheimer's Disease Patients

Background : Prospective memory is known as the memory of a plan to carry out an intended action in the future. Although it is associated with many activities in everyday life, to date there have been no well controlled laboratory studies of prospective memory in patients with Alzheimer's dementia (AD). In this study, we investigated the ability of prospective memory in AD subjects using an event-based prospective memory task in which prospective remembering is triggered by a specific external cue.
Methods : Using a personal computer, we conducted event-based prospective memory tasks embedded in the Stroop task. The concurrent cognitive task such as the Stroop task was called the ongoing task. In the event-based prospective memory task, subjects were required to react by pressing a mouse key whenever a stimulus during the Stroop task (identification of the name of a color printed in black, of the correct color of a colored circle, or the name of a color printed in an incorrect color) appeared in a larger-than-normal size. This target stimulus was designed to appear eight times in each condition, i.e., word condition, color condition, and incorrect-color condition, during the Stroop task.
Results : Normal elderly people showed good event-based prospective memory performance across all three conditions in the Stroop task. In contrast, AD subjects performed poorly in the event-based prospective memory task under the incorrect-color condition in the Stroop task.
Conclusion : This study indicated that an ongoing concurrent task with a high attention demand affects the performance of event-based prospective memory in AD subjects. The performance of event-based prospective memory in AD subjects was more sensitive to the Stroop interference effect observed in the ongoing task than in normal elderly people. The breakdown of this event-based prospective memory may reflect the limited attention capacity of AD subjects.     

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.     

Transitivity performance,relational hierarchy knowledge and awareness: Results of an instructional framing manipulation

The transitive inference (TI) paradigm has been widely used to examine the role of the hippocampus in generalization. Here we consider a surprising feature of experimental findings in this task: the relatively poor transitivity performance and levels of hierarchy knowledge achieved by adult human subjects. We focused on the influence of the task instructions on participants' subsequent performance—a single‐word framing manipulation which either specified the relation between items as transitive (i.e., OLD‐FRAME: choose which item is “older”) or left it ambiguous (i.e., NO‐FRAME: choose which item is “correct”). We show a marked but highly specific effect of manipulating prior knowledge through instruction: transitivity performance and levels of relational hierarchy knowledge were enhanced, but premise performance unchanged. Further, we show that hierarchy recall accuracy, but not conventional awareness scores, was a significant predictor of inferential performance across the entire group of participants. The current study has four main implications: first, our findings establish the importance of the task instructions, and prior knowledge, in the TI paradigm—suggesting that they influence the size of the overall hypothesis space (e.g., to favor a linear hierarchical structure over other possibilities in the OLD‐FRAME). Second, the dissociable effects of the instructional frame on premise and inference performance provide evidence for the operation of distinct underlying mechanisms (i.e., an associative mechanism vs. relational hierarchy knowledge). Third, our findings suggest that a detailed measurement of hierarchy recall accuracy may be a more sensitive index of relational hierarchy knowledge, than conventional awareness score—and should be used in future studies investigating links between awareness and inferential performance. Finally, our study motivates an experimental setting that ensures robust hierarchy learning across participants—therefore facilitating study of the neural mechanisms underlying the learning and representation of linear hierarchies. © 2013 The Authors. Hippocampus Published by Wiley Periodicals, Inc.     

Editors’ Introduction: Remembering With Others: Conversational Dynamics and Mnemonic Outcomes

Remembering the past through conversations with others is a uniquely human endeavor. Conversational remembering consists of specific dynamics and can lead to mnemonic outcomes. While conversational dynamics refer to the interactive processes (e.g., the roles speakers and listeners may undertake during the conversation) shaping collaborative remembering, conversational outcomes are about the mnemonic and functional consequences (e.g., forging social bonds) of those processes. Thus, the aim of the present article is to introduce the reader to key concepts and paradigms that have been rigorously developed to empirically investigate the dynamics and outcomes of conversational remembering in cognitive research. The collected review and empirical articles gathered in this topic provide the state‐of‐the‐art in the field.     

Priming for novel between-word associations in patients with organic amnesia.

Ten amnesic patients of various etiologies and 10 matched normal controls participated in this study. On 2 consecutive days, subjects studied 30 novel word-word associations 6 times. Using a cued recall task, we assessed episodic learning and delayed retention of the study material immediately after each study phase and again 24 hr after the final study phase. Further, we evaluated implicit memory for new between-word associations by means of an automatic relational priming paradigm immediately after the delayed cued recall trial. Amnesic patients performed poorly on the cued recall task. Moreover, in the overall group of amnesics the priming effect failed to reach statistical significance. When the overall group of amnesics was split according to mean performance on the cued recall task, those in the low performer subgroup--comprised of 6 patients with direct or indirect involvement of the hippocampi--were particularly poor at episodically remembering the associations and did not reveal any relational priming. These data support the hypothesis of similar impairment of new episodic and implicit learning in amnesic patients and suggest that the hippocampus is crucial for both kinds of new learning.     

Sparing of perceptual implicit memory despite suppression of the electrophysiological word repetition effect: a study with general anesthetic isoflurane.

OBJECTIVE: Much effort has been devoted to the search for the neurophysiological correlates of implicit memory. A commonly held view is that the early portion (250-500 ms) of the event-related potential (ERP) word repetition effect reflects processes important for perceptual implicit memory whereas the latter portion reflects processes implicated in explicit memory. It is, however, difficult to disentangle with certainty the relative contributions of each form of memory on ERPs since both forms co-exist in normal subjects. To dissociate ERP effect related to implicit and explicit memory, we used isoflurane sedation in normal subjects to suppress explicit remembering while sparing implicit memory. These ERPs were compared with those of non-medicated control subjects. METHODS: Thirteen subjects performed an incidental encoding task for words presented auditorily during the inhalation of a subanesthetic dose of isoflurane. After termination of isoflurane administration, we assessed free recall and recorded ERPs during a syllable completion task (implicit memory) and during a passive listening task (ERP repetition effect). Eleven non-medicated control subjects were tested in a similar manner. RESULTS: The controls showed robust early and late ERP repetition effect. The isoflurane group had implicit memory without free recall and showed no ERP repetition effect. CONCLUSIONS: These findings failed to show an association between any part of the repetition effect and perceptual implicit memory. The results are consistent with the view that processes linked to explicit memory contribute to the ERP repetition effect since there was a marked difference in free recall between the control and isoflurane groups. SIGNIFICANCE: The present study shows that the reversible alterations of memory by general anesthetics can be used to study the neurophysiological correlates of memory processes.     

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.     

Mnemonic training in older adults: effects of age, length of training, and type of cognitive pretraining

OBJECTIVES: To improve performance with mnemonic techniques for remembering words and proper names. DESIGN: For word recall, a 2 x 2 factorial in which type of pretraining and length of training were between-subjects manipulations. For proper name recall, a two-group design in which type of pretraining was manipulated between subjects. SETTING: Community. PARTICIPANTS: 268 community-dwelling adults over the age of 55 years who wished to improve their memory. MEASUREMENTS: Recall of words and proper names both before and after training in mnemonics. INTERVENTION: Participants received a 2-week training course on two mnemonic techniques, the method of loci for words and a name association technique for proper names. RESULTS: There was no effect of the pretraining manipulation on proper name recall. For word recall, however, a multiple regression that included age indicated that the older-old participants benefited more from a combination of comprehensive pretraining and extended mnemonic training than did the younger-old. CONCLUSIONS: Increased training time coupled with a comprehensive pretraining regimen can improve the performance of the older-old in using mnemonics; this improved performance cannot be attributed solely to enhanced knowledge of the mnemonic.     

Face–name association learning in early Alzheimer's disease: A comparison of learning methods and their underlying mechanisms

This study compared the efficacy of five learning methods in the acquisition of face–name associations in early dementia of Alzheimer type (AD). The contribution of error production and implicit memory to the efficacy of each method was also examined. Fifteen participants with early AD and 15 matched controls were exposed to five learning methods: spaced retrieval, vanishing cues, errorless, and two trial-and-error methods, one with explicit and one with implicit memory task instructions. Under each method, participants had to learn a list of five face–name associations, followed by free recall, cued recall and recognition. Delayed recall was also assessed. For AD, results showed that all methods were efficient but there were no significant differences between them. The number of errors produced during the learning phases varied between the five methods but did not influence learning. There were no significant differences between implicit and explicit memory task instructions on test performances. For the control group, there were no differences between the five methods. Finally, no significant correlations were found between the performance of the AD participants in free recall and their cognitive profile, but generally, the best performers had better remaining episodic memory. Also, case study analyses showed that spaced retrieval was the method for which the greatest number of participants (four) obtained results as good as the controls. This study suggests that the five methods are effective for new learning of face–name associations in AD. It appears that early AD patients can learn, even in the context of error production and explicit memory conditions.     

Brain‐derived neurotrophic factor interacts with adult‐born immature cells in the dentate gyrus during consolidation of overlapping memories

Successful memory involves not only remembering information over time but also keeping memories distinct and less confusable. The computational process for making representations of similar input patterns more distinct from each other has been referred to as “pattern separation.” Although adult‐born immature neurons have been implicated in this memory feature, the precise role of these neurons and associated molecules in the processing of overlapping memories is unknown. Recently, we found that brain‐derived neurotrophic factor (BDNF) in the dentate gyrus is required for the encoding/consolidation of overlapping memories. In this study, we provide evidence that consolidation of these “pattern‐separated” memories requires the action of BDNF on immature neurons specifically. © 2014 The Authors. Hippocampus Published by Wiley Periodicals, Inc.     

Unilateral Prefrontal Direct Current Stimulation Effects are Modulated by Working Memory Load and Gender

BackgroundRecent studies revealed that anodal transcranial direct current stimulation (tDCS) to the left dorsolateral prefrontal cortex (DLPFC) may improve verbal working memory (WM) performance in humans. In the present study, we evaluated executive attention, which is the core of WM capacity, considered to be significantly involved in tasks that require active maintenance of memory representations in interference-rich conditions, and is highly dependent on DLPFC function.ObjectivesWe investigated verbal WM accuracy using a WM task that is highly sensitive to executive attention function. We were interested in how verbal WM accuracy may be affected by WM load, unilateral DLPFC stimulation, and gender, as previous studies showed gender-dependent brain activation during verbal WM tasks.MethodsWe utilized a modified verbal n-Back task hypothesized to increase demands on executive attention. We examined “online” WM performance while participants received transcranial direct current stimulation (tDCS), and implicit learning performance in a post-stimulation WM task.ResultsSignificant lateralized “online” stimulation effects were found only in the highest WM load condition revealing that males benefit from left DLPFC stimulation, while females benefit from right DLPFC stimulation. High WM load performance in the left DLPFC stimulation was significantly related to post-stimulation recall performance.ConclusionsOur findings support the idea that lateralized stimulation effects in high verbal WM load may be gender-dependent. Further, our post-stimulation results support the idea that increased left hemisphere activity may be important for encoding verbal information into episodic memory as well as for facilitating retrieval of context-specific targets from semantic memory.     

Disentangling working memory processes during spatial span assessment: A modeling analysis of preferred eye movement strategies

The neurocognitive processes involved during classic spatial working memory (SWM) assessment were investigated by examining naturally preferred eye movement strategies. Cognitively healthy adult volunteers were tested in a computerized version of the Corsi Block-Tapping Task—a spatial span task requiring the short term maintenance of a series of locations presented in a specific order—coupled with eye tracking. Modeling analysis was developed to characterize eye-tracking patterns across all task phases, including encoding, retention, and recall. Results revealed a natural preference for local gaze maintenance during both encoding and retention, with fewer than 40% fixated targets. These findings contrasted with the stimulus retracing pattern expected during recall as a result of task demands, with 80% fixated targets. Along with participants’ self-reported strategies of mentally “making shapes,” these results suggest the involvement of covert attention shifts and higher order cognitive Gestalt processes during spatial span tasks, challenging instrument validity as a single measure of SWM storage capacity.     

Temporal context discrimination in patients with schizophrenia: associations with auditory hallucinations and negative symptoms

BACKGROUND: A deficit in remembering the temporal context of events (a type of source memory) has been observed in schizophrenia, and suggested to be associated with positive symptoms. METHODS: In order to investigate memory for temporal context, we administered a list discrimination task to a sample of schizophrenia patients and a sample of healthy controls. Participants were required to learn two lists of mixed high- and low-frequency words separated by 10 min, then to remember whether each word had been presented in the first or in the second list. RESULTS: The number of misattributions to the wrong list was significantly higher in patients than in healthy controls. However, the group difference was eliminated when recall efficiency was covaried. The number of list misattributions was higher in patients with auditory hallucinations than in the other patients, independently of verbal recall efficiency. By contrast, affective flattening and anhedonia were associated with fewer list misattributions of the high-frequency words. CONCLUSIONS: It is suggested that auditory hallucinations are associated with deficit in processing or remembering the temporal context. Conversely, certain negative symptoms are associated with reduced temporal context errors. The possible neural mechanisms involved in temporal context deficit as well as in these specific clinical symptoms are discussed.     

A case of unusual autobiographical remembering

This report describes AJ, a woman whose remembering dominates her life. Her memory is "nonstop, uncontrollable, and automatic." AJ spends an excessive amount of time recalling her personal past with considerable accuracy and reliability. If given a date, she can tell you what she was doing and what day of the week it fell on. She differs from other cases of superior memory who use practiced mnemonics to remember vast amounts of personally irrelevant information. We propose the name hyperthymestic syndrome, from the Greek word thymesis meaning remembering, and that AJ is the first reported case.