Rehearsal strategy use in Alzheimer's disease

Memory strategy usage and awareness of memory performance are both crucial for memory rehabilitation. We explored Alzheimer's patients' ability to apply and control learning strategies and also their ability to predict the effect of these strategies on subsequent performance. In a rehearsal condition, participants were explicitly asked to overtly rehearse words and were given as long as they liked at study. In a control condition, participants read the words passively at a fixed presentation rate. In all groups, recall was superior in the rehearsal condition than in the reading condition. Alzheimer's patients showed different strategy usage. Overall, people with Alzheimer's disease spend longer studying to-be-remembered words under unpaced conditions, but they do not use this time to rehearse to the same extent as controls. We hypothesize that this failure to rehearse could be based on the inability to use effortful executive mechanisms involved during study.     

Rehearsal Strategies and Recall Performance in Boys With and Without Attention Deficit Hyperactivity Disorder

Examined differences in recall performance and rehearsal strategiesin boys with Attention Deficit Hyperactivity Disorder (ADHD)and comparison boys using an overt rehearsal procedure on aself-paced, multitrial, free recall task. Boys with ADHD recalledfewer words, tended to spend less time rehearsing the items,and spent less time attempting to retrieve them. Although theydid not rehearse items less frequently than comparison boys,they relied almost exclusively on repetition of single items.In contrast, comparison boys showed some evidence of using active,multi-item (cumulative) rehearsal. Despite their failure touse cumulative rehearsal, boys with ADHD identified it as moreeffective than single-item rehearsal in a subsequent forced-choiceassessment of strategy knowledge.     

Visual versus verbal mnemonic training effects on memory‐deficient and language‐deficient subgroups of children with reading disability

This study compared the effectiveness of two different memory strategies for memory‐deficit, reading‐disabled (RD) children with different cognitive patterns. Forty learning‐disabled children 7 to 13 years old were divided into two groups based on whether they showed general language disorder (GLD) or specific memory disorder (SMD) without a language deficit. Each child was then given training in one of two memory strategies: visual mapping or cumulative verbal rehearsal. Subsequent memory performance of the two RD subgroups was compared over the two treatment conditions. There was a significant interaction in the effectiveness of the two treatments for the two groups’ memory performance after treatment. GLD children made significantly greater gains from pretesting to posttesting on the visual mapping treatment than on the cumulative verbal rehearsal treatment, whereas the SMD children demonstrated significantly greater gains on cumulative verbal rehearsal than on visual mapping. The findings suggest that there is a relation between an RD child's cognitive strengths and deficits and ability to employ a given memory strategy effectively.     

Individual differences in strategy use in the Japanese reading span test

Working memory is a system for processing and storing information. The Reading Span Test (RST), developed by Daneman and Carpenter (1980), is well-known for assessing individual difference in working memory. In the present investigation, we used the Japanese version of the RST (Osaka, 2002) and analyzed individual differences in strategy use from the viewpoint of strategy type (rehearsal, chaining, word-image, scene-image, and initial letter) and frequency of use (used in almost all trials, in half the trials, or not used). Data from the participants (N = 132) were assigned to groups according to the scores, for the total number of words correctly recalled and the proportion correct. The results showed that the frequency of word-image strategy use differed significantly between high-scoring subjects (HSS) and low-scoring subjects (LSS). HSS mainly used word-image and chaining strategies, while LSS used rehearsal and chaining strategies. This indicates that HSS used both verbal and visual strategies, whereas LSS relied only on verbal strategies. The use of the word-image is important for effective retention of words in memory.     

VERIDICAL AND FALSE MEMORIES IN HEALTHY OLDER ADULTS AND IN DEMENTIA OF THE ALZHEIMER'S TYPE

Five groups of participants (young, healthy old, healthy old-old, very mild Dementia of the Alzheimer's Type, Mild Dementia of the Alzheimer's Type) studied and were tested on six 12-item lists of words selected from the DRM (Deese, 1959; Roediger & McDermott, 1995) materials. These lists of words strongly converged semantically on a nonpresented critical word. The results indicated that both veridical recall and recognition performance decreased both as a function of age of the participants and as a function of dementia severity. However, the recall and recognition of the highly related nonpresented items actually increased as a function of age, and only slightly decreased as a function of DAT. When false memory was considered as a proportion of veridical memory, there was a clear increase as a function of both age of the participants and as a function of disease severity. The results are discussed in terms of (a) age and DAT-related changes in attention and memory performance, and (b) the underlying mechanisms that produce false memories in the DRM paradigm.     

P300 and Recall in an Incidental Memory Paradigm

In previous research Karis, Fabiani, and Donchin (1984) found a relationship between the amplitude of the P300s elicited by words and subsequent recall performance. Words later recalled elicited larger P300s than words later not recalled. However, this relationship was dependent on the mnemonic strategies used by the subjects. There was a strong relationship between P300 amplitude and recall when rote rehearsal strategies were used, but when subjects used elaborative strategies the relationship between P300 amplitude and recall was not evident. In the present experiment we employed an incidental memory paradigm to reduce the use of rehearsal strategies. An “oddball’ task consisting of a series of names was presented, and subjects were required to count either the male or the female names. Event-related brain potentials were recorded to the presentation of each name. Following the oddball task, subjects were asked, unexpectedly, to recall as many names as possible. The names that were recalled had elicited, on their initial presentation, larger P300s than names not recalled. Thus, these results confirm our hypothesis: when elaborative rehearsal strategies are not used, the relationship between P300 and memory emerges more consistently. Our data provide support for a “context updating’ hypothesis of the functional significance of the P300.     

Erythropoietin improves spatial learning and memory in streptozotocin model of dementia

Alzheimer's disease is associated to impairments of learning and memory. Because studies demonstrated that erythropoietin has positive effects on central nervous system, the aim of this study was to evaluate the effect of erythropoietin on spatial learning and memory in a well defined model for Alzheimer's disease. Rat model of Alzheimer's was created by injecting streptozotocin in lateral ventricles of the brain. Two weeks later, the rats were assessed through passive avoidance learning test to confirm the induction of Alzheimer's. After that, they received erythropoietin (5000 IU/kg) every other day, for two weeks and then spatial learning and memory were assessed by a 5-day protocol of Morris water maze test in them. The results showed that streptozotocin severely damaged learning and memory in rats. Erythropoietin had no significant effect in the control rats; however, it significantly improved learning and memory in rats with Alzheimer's disease, as the task performance of the rats treated with erythropoietin was like the control group. The results suggest that erythropoietin can be considered as an effective treatment for neurodegenerative damages.     

The effects of test expectancy and rehearsal strategies on recall in the situation of simultaneous presentation

The present experiment was carried out to examine the effects of verbal instruction of rehearsal strategy and test expectancy of final recall on immediate and final recall, in the situation of simultaneous presentation of items. Subjects' spontaneous rehearsal activities were also explored by means of a revised version of questionnaire regarding rehearsal substrategies. Ninety undergraduates participated in this experiment. The resulting data indicated performance under the associative rehearsal instruction was better than that of rote rehearsal instruction in final recall, but was not in immediate recall. In both immediate and final tests, there was no difference of performance between subjects instructed to rehearse repetitively and spontaneously. The effect of test expectancy was found in final recall, and was interpreted to be owing to frequent use of substrategies relating imagery and intra-list association from the result of questionnaire.     

Neural correlates of motor imagery for elite archers

Motor imagery is a mental rehearsal of simple or complex motor acts without overt body movement. It has been proposed that the association between performance and the mental rehearsal period that precedes the voluntary movement is an important point of difference between highly trained athletes and beginners. We compared the activation maps of elite archers and nonarchers during mental rehearsal of archery to test whether the neural correlates of elite archers were more focused and efficiently organised than those of nonarchers. Brain activation was measured using functional MRI in 18 right‐handed elite archers and 18 right‐handed nonarchers. During the active functional MRI imagery task, the participants were instructed to mentally rehearse their archery shooting from a first‐person perspective. The active imagery condition was tested against the nonmotor imagery task as a control condition. The results showed that the premotor and supplementary motor areas, and the inferior frontal region, basal ganglia and cerebellum, were active in nonarchers, whereas elite archers showed activation primarily in the supplementary motor areas. In particular, our result of higher cerebellar activity in nonarchers indicates the increased participation of the cerebellum in nonarchers when learning an unfamiliar archery task. Therefore, the difference in cerebellar activation between archers and nonarchers provides evidence of the expertise effect in the mental rehearsal of archery. In conclusion, the relative economy in the cortical processes of elite archers could contribute to greater consistency in performing the specific challenge in which they are highly practised. Copyright © 2010 John Wiley & Sons, Ltd.     

Choosing Alzheimer's disease prevention clinical trial populations

To assist investigators in making design choices, we modeled Alzheimer's disease prevention clinical trials. We used longitudinal Clinical Dementia Rating Scale Sum of Boxes data, retention rates, and the proportions of trial-eligible cognitively normal participants age 65 and older in the National Alzheimer's Coordinating Center Uniform Data Set to model trial sample sizes, the numbers needed to enroll to account for drop out, and the numbers needed to screen to successfully complete enrollment. We examined how enrichment strategies affected each component of the model. Relative to trials enrolling 65-year-old individuals, trials enriching for older (minimum 70 or 75) age required reduced sample sizes, numbers needed to enroll, and numbers needed to screen. Enriching for subjective memory complaints reduced sample sizes and numbers needed to enroll more than age enrichment, but increased the number needed to screen. We conclude that Alzheimer's disease prevention trials can enroll elderly participants with minimal effect on trial retention and that enriching for older individuals with memory complaints might afford efficient trial designs.     

Identifying deliberate attempts to fake memory impairment through the combined use of reaction time and event-related potential measures

The central aim of this study was to evaluate the value of reaction time (RT) measures and event-related potentials (ERPs) for the assessment of simulated memory impairment. In two identical experiments (N = 24), healthy volunteers carried out an adapted version of the Amsterdam Short-Term Memory (ASTM) test. In half of the cases participants were instructed to perform to their best of abilities (control condition) while in the other half participants were asked to feign a believable memory deficit (simulation condition). Compared to controls, simulating participants were found to produce longer and more variable RTs. In addition, they took longer to respond to new words than to old words, while control participants showed the opposite pattern. Both early (300–500 ms) and late (500–800 ms) ERP old/new effects were similar in magnitude and scalp distribution for both groups of participants, regardless of the fact that simulating participants had significantly lower recognition accuracy than controls. The ERP old/new effect was assumed to reflect unaffected retrieval mechanisms and thus the discrepancy between this measure and recognition performance was interpreted as evidence for intentional underperformance. Results are discussed in relation to clinical observations and deception detection studies. It was concluded that the combined use of RT and ERP measures could be useful to detect and evaluate simulation of memory impairment but that future studies should include patient groups to test some of our assumptions.     

Short-term forgetting in senile dementia of the Alzheimer's type

Abstract

This study explored the nature of forgetting in a group of patients at the early stages of senile dementia of the Alzheimer's type (SDAT). Two experiments were conducted to test the hypothesis that abnormal forgetting in SDAT is due to a reduction in central processing resources, leading to deficits in maintenance rehearsal.

The first experiment tested the patients' ability to remember consonant trigrams after an interval of 0, 5, 10 or 20 seconds, during which they were either instructed to do nothing, articulate the word “the” repeatedly, reverse pairs of digits or add pairs of digits together. The articulation distractor task caused substantial forgetting with SDAT patients in comparison with minimal forgetting in an elderly control group. They were also clearly impaired with digit reversal and digit addition as distractor tasks, although their forgetting rates were similar to the controls. The second experiment showed a substantial decrement in the SDAT patients' ability to remember consonant trigrams with both tapping and articulation as distractor tasks. Overall, these results support the hypothesis that SDAT patients have insufficent central processing resources available for maintenance rehearsal.     

Dissociating the effects of semantic grouping and rehearsal strategies on event-related brain potentials

The application of elaborative encoding strategies during learning, such as grouping items on similar semantic categories, increases the likelihood of later recall. Previous studies have suggested that stimuli that encourage semantic grouping strategies had modulating effects on specific ERP components. However, these studies did not differentiate between ERP activation patterns evoked by elaborative working memory strategies like semantic grouping and more simple strategies like rote rehearsal. Identification of neurocognitive correlates underlying successful use of elaborative strategies is important to understand better why certain populations, like children or elderly people, have problems applying such strategies. To compare ERP activation during the application of elaborative versus more simple strategies subjects had to encode either four semantically related or unrelated pictures by respectively applying a semantic category grouping or a simple rehearsal strategy. Another goal was to investigate if maintenance of semantically grouped vs. ungrouped pictures modulated ERP-slow waves differently. At the behavioral level there was only a semantic grouping benefit in terms of faster responding on correct rejections (i.e. when the memory probe stimulus was not part of the memory set). At the neural level, during encoding semantic grouping only had a modest specific modulatory effect on a fronto-central Late Positive Component (LPC), emerging around 650 ms. Other ERP components (i.e. P200, N400 and a second Late Positive Component) that had been earlier related to semantic grouping encoding processes now showed stronger modulation by rehearsal than by semantic grouping. During maintenance semantic grouping had specific modulatory effects on left and right frontal slow wave activity. These results stress the importance of careful control of strategy use when investigating the neural correlates of elaborative encoding.     

Illusory Reduplication of One's Own Body: Phenomenology and Classification of Autoscopic Phenomena

Introduction. Cognitive deficits are commonly reported in schizophrenia and have a significant impact on the daily life of patients and on their social and work inclusion. Cognitive remediation therapies (CRT) may enhance the capabilities of schizophrenia patients. Although social and work integration is the ultimate goal of CRT, previous studies have failed to carry out a detailed assessment of the effects on everyday life.

Methods. Fifty-nine schizophrenia patients were randomised into two groups (remediation or usual treatment) to test the effects of a new remediation programme, which included both rehearsal and strategy learning, on cognitive functions. An ecological test was used to evaluate its transfer to daily living skills.

Results. Cognitive improvements are revealed in CRT patients, mainly in memory and executive functions. Patients showing some deficiencies to perform the ecological test had better scores after the CRT. Moreover, they significantly improve their social activity scores.

Conclusions. CRT would facilitate mental load monitoring by enhancing or reallocating cognitive resources, facilitating the patient's organisation and autonomy. The rehearsal learning approach improves the ability to carry out automatic operations that are less demanding in terms of cognitive resources, thereby increasing the resources available for acquisition and efficient use of strategies provided during the strategy learning approach.     

Changes in immediate visual memory predict cognitive impairment

Six-year changes in immediate visual memory performance assessed by the Benton Visual Retention (BVR) test predicted Alzheimer's disease (AD) prior to its onset. Subjects of this study were 371 community-dwelling adult participants in the Baltimore Longitudinal Study of Aging, seven of whom received probable or definite AD diagnoses using DSM-III-R and NINCDS-ADRDA criteria. Subjects with diagnoses of AD had larger changes in immediate memory performance over the 6-year interval prior to the estimated onset of their disease than subjects without AD. Six-year longitudinal change as well as level in immediate visual memory performance also predicted subsequent cognitive performance 6–15 and 16–22 years later, even after adjusting for the influences of age, general ability, and initial immediate memory. These results provide evidence that change and level in immediate visual memory performance has long-term prognostic significance over as many as 16–22 years. These results further suggest that change in recent memory performance, an important component in AD diagnoses, may be an important precursor of the development of the disease.     

Constraining theories of semantic memory processing: Evidence from Dementia

In this paper we analyse the performance of ten patients with Dementia of the Alzheimer's Type (D.A.T.) who show a pattern of performance suggesting a deficit at the level of semantic memory in the face of normal visual perceptual processing. We use the results of their performance on probe questions for pictures and words to evaluate several hypotheses arising from recent theories concerning semantic memory. We assess whether these patients demonstrate better performance on pictures than words (they do), and whether this can be explained away as a by-product of the perceptual nature of the items tested; pictures whose items have many discernible object parts would tend to contact more residual information in semantic memory, thus producing apparent superior performance from pictures. In fact, we find no support for this explanation. Rather, we are able to demonstrate, in the semantic category of animals, that it is only the items that are correctly identified (as a whole) that will give rise to evidence of better performance on pictures.

We then go on to demonstrate that, in contrast to theories suggesting the presence of multiple stores within semantic memory, error analysis of our patients suggests that associative conceptual knowledge is stored amodally … loss of such functional knowledge for pictures is usually accompanied by equal loss of the same information for words.

In the discussion section, we present theoretical arguments for a distinction between two kinds of semantic processing; the routines involved in the identification and categorisation of visual instances of concepts, and the associative framework that constitutes our full knowledge of such concepts. We suggest that such a framework is most consistent with the data from our patients. Despite arguments that present theories of semantics are too vague for empirical study, it is possible to test particular elements of such theories and provide data that supports or opposes them.     

Dissociating the effects of semantic grouping and rehearsal strategies on event-related brain potentials

The application of elaborative encoding strategies during learning, such as grouping items on similar semantic categories, increases the likelihood of later recall. Previous studies have suggested that stimuli that encourage semantic grouping strategies had modulating effects on specific ERP components. However, these studies did not differentiate between ERP activation patterns evoked by elaborative working memory strategies like semantic grouping and more simple strategies like rote rehearsal. Identification of neurocognitive correlates underlying successful use of elaborative strategies is important to understand better why certain populations, like children or elderly people, have problems applying such strategies. To compare ERP activation during the application of elaborative versus more simple strategies subjects had to encode either four semantically related or unrelated pictures by respectively applying a semantic category grouping or a simple rehearsal strategy. Another goal was to investigate if maintenance of semantically grouped vs. ungrouped pictures modulated ERP-slow waves differently. At the behavioral level there was only a semantic grouping benefit in terms of faster responding on correct rejections (i.e. when the memory probe stimulus was not part of the memory set). At the neural level, during encoding semantic grouping only had a modest specific modulatory effect on a fronto-central Late Positive Component (LPC), emerging around 650 ms. Other ERP components (i.e. P200, N400 and a second Late Positive Component) that had been earlier related to semantic grouping encoding processes now showed stronger modulation by rehearsal than by semantic grouping. During maintenance semantic grouping had specific modulatory effects on left and right frontal slow wave activity. These results stress the importance of careful control of strategy use when investigating the neural correlates of elaborative encoding.     

How people process increasing amounts of information as trials go on: reduction of the trade-off between memory and information-processing in the mental resources

In solving problems in which the amount of memory required increases during the course of solution the subjects would select such strategies as to cope with the deterioration of performance due to the trade-off between the memory load and the information-processing efficiency. To test the above hypothesis 58 graduates and undergraduates were asked to solve a number-guessing problem. In Experiment I, the subjects' responses were categorized and two different information-processing strategies were extracted; the condensation-of-information strategy and the partiality-decision strategy. These strategies were coded as flow charts. In Experiment II, to clarify the relation between processing and memory strategies, memory load was varied by giving the subjects different amount of cues for the solution. Results suggested that the subjects coped flexibly with the demand of situation by adaptive usage of two-layer solving strategies corresponding to the amount of memory load; one was a memory strategy and the other was a processing strategy.     

Dual-task interference between climbing and a simulated communication task

Climbers often need to maintain communication with other people. Previous research indicates that climbers remember less of the information communicated to them while climbing than when not climbing. In the present research, we investigated at what stage of memory the source of this impairment occurs. Participants were required to respond to words presented to them by saying out loud an associated word. This enforced encoding of the words, and was completed alone, as well as while climbing. Participants then recalled as many words as possible. A separate single-task condition had participants climb without making word associations. Word recall was reduced in the dual-task compared with the single word association task, but there was no difference in the number of word associations made. This indicates that the reduction in word recall was not a result of reduced encoding in the dual-task condition. Concurrent climbing may have reduced word recall by interfering with rehearsal and maintenance of words in memory.     

Effects of treadmill exercise on memory and c-Fos expression in the hippocampus of the rats with intracerebroventricular injection of streptozotocin

Alzheimer's disease is a progressive neurodegenerative disease clinically characterized by dementia and neurobehavioral deterioration. Hippocampal neurons are vulnerable to injury induced by Alzheimer's disease. The immediate early gene c-Fos has been used as a marker of neuronal activity. In the present study, we investigated the effects of treadmill exercise on long-term memory capacity and c-Fos expression in the hippocampus of rats with Alzheimer's disease. The rat model of Alzheimer's disease used in the present study was induced by the intracerebroventricular (ICV) injection of streptozotocin (STZ) using a stereotaxic instrument. The rats in the exercise group were forced to run on a treadmill for 30 min once daily for 14 consecutive days starting at 3 days after the ICV injection of STZ. The results of the present study showed that ICV injection of STZ impaired long-term memory capacity and decreased the number of c-Fos-positive cells in several regions of the rat hippocampus. However, treadmill exercise alleviated long-term memory deficits and enhanced c-Fos expression in the rats with ICV injection of STZ. The results of the present study showed that treadmill exercise could be a useful strategy for treating several neurodegenerative diseases.