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PubMed2001

Memory and metamemory performance in Alzheimer's disease and healthy elderly: the Contextual Memory Test (CMT).

The purpose of the present study was to examine the ability of the Contextual Memory Test (CMT) to differentiate between elderly people suffering from Alzheimer's disease (AD) in comparison to healthy elderly people. Specifically, the objectives were to compare for differences between and within the groups on components of memory, including immediate and delayed recall as well as recognition. In addition, parameters of metamemory skills, such as general awareness, self-prediction of memory capacity, self-estimation, strategy use and use of contextual information, as well as the correlation between self-awareness and actual performance in both groups, were investigated. The sample consisted of 60 elderly participants, including 30 people diagnosed with AD who were assigned to the research group and 30 people matched for age, gender and educational level who were assigned to the control group. The results provide support for the hypothesis positing differences in memory performance between healthy elderly participants and those suffering from AD, particularly in immediate and delayed recall as well as in recognition. Moreover, findings indicate an improvement in memory performance under the cued condition (contextual), whereas improvement in the AD group proved to be significant only for immediate recall. The findings point to a distinct overestimation of memory ability predicted by both the AD and control groups. Following the memory task, however, the participants accurately estimated the number of items they remembered. In addition, significant correlations between the use of contextual and association strategies and the number of items remembered by both groups were obtained, in immediate as well as in delayed recall. Therefore, these findings support the CMT as a valuable memory and metamemory assessment tool for use with the AD population.

Aged↗

PubMed2002

Memory consolidation and the hippocampus: further evidence from studies of autobiographical memory in semantic dementia and frontal variant frontotemporal dementia.

Studies of autobiographical memory in semantic dementia have found relative preservation of memories for recent rather than remote events. As semantic dementia is associated with progressive atrophy to temporal neocortex, with early asymmetric sparing of the hippocampus, this neuropsychological pattern suggests that the hippocampal complex plays a role in the acquisition and retrieval of recent memories, but is not necessary for the recall of older episodic events. In an alternative view of memory consolidation, however, the hippocampus plays a role in the retrieval of all autobiographical memories, regardless of the age of the memory [Curr. Opin. Neurobiol. 7(1997)217]. This 'multiple trace theory' predicts that patients with semantic dementia should show no effects of time in their autobiographical recall. In this article, we ask whether it is possible to reconcile the data from semantic dementia with the multiple trace theory by investigating whether the time-dependent pattern of autobiographical retrieval seen in the disease is due to (i) patients showing this effect being exceptional in their presentation; and/or (ii) patients with semantic dementia exhibiting impaired strategic retrieval from concomitant frontal damage. A series of experiments in patients with semantic dementia, the frontal variant of frontotemporal dementia and Alzheimer's disease clearly demonstrates that neither of these two factors can explain the documented effect of time seen in semantic dementia. Nonetheless, we discuss how damage to semantic knowledge could result in an autobiographical memory deficit and suggest that data from semantic dementia may be consistent with both views of hippocampal involvement in long-term memory.

Aged↗

PubMedDate not supplied

In two species, females exhibit superior working memory and inferior reference memory on the water radial-arm maze.

Male and female mice and rats were tested on a water escape version of the radial-arm maze designed to measure working and reference memory. In both species, females exhibited superior working memory during acquisition, and were better able to handle a higher memory load. However, male mice and rats exhibited better reference memory than females during the asymptotic portion of testing. Our data suggest that females may be better at working memory when both working and reference memory information must be learned simultaneously, and males better at reference memory when it has been differentiated from working memory.

Animals↗

PubMed2001

Is the HM story only a "remote memory"? Some facts about hippocampus and memory in humans.

In this review, we argue that a number of current data support the notion that the hippocampal formations play an important role in episodic memory in humans. We will focus on data gathered from three topics within this field: (1) the neuropsychological study of memory in degenerative diseases, which provides striking dissociations of processes, as a function of the location of cerebral lesions and of their functional consequences; (2) the description of patients' memory difficulties after unilateral medial temporal lobectomy. Given the visuo-verbal dissociation, we may anticipate that the study of the effects of such lesions may help in the understanding of the role of the hippocampus in memory, in terms of: (i) the stage of memory processing where the hippocampus is really involved (encoding, consolidation and/or retrieval); (ii) the specificity of the impairments as a function of the nature (verbal vs. visuo-spatial) of the to-be-remembered material; (3) recent evidence from imaging studies: (i) the morphological approach, which provides interesting information with the study of correlations between the volumes of diverse cerebral regions-particularly the volume of the hippocampus-and episodic memory performance and other cognitive measures; (ii) metabolic studies, using PET scan, which were first designed for correlational analyses between performance in episodic memory tasks and glucose utilization at rest in diverse regions of interest, such as the hippocampal formations; (iii) activation studies with PET and functional MRI, which are actually more straightforward, since they allow correlations between the metabolism in regions of interest and performance on line (e.g. during encoding or retrieval of information). In our view, inasmuch as such different approaches-degenerative diseases, lesions or imagery-provide convergent information, they give renewed weight to the notion according to which the hippocampal formations are critically concerned in episodic memory processes.

Aging↗

PubMedDate not supplied

The relationships between working memory and long-term memory.

Recent studies have led to the proposal that working memory operates not as a gateway between sensory input and long-term memory but as a workspace. The core of argument is that access to acquired knowledge and prior learning occurs before information becomes available to working memory. This proposition is a way to accommodate Baddeley's multiple component working memory model and the view that considers that working memory is nothing other than temporary activations of representations and procedures in long-term memory. However, this 'workspace' conception of working memory raises the question of the relationships between the central executive system and long-term memory.

Humans↗

PubMed2003

Autobiographical memory in schizophrenia: an examination of the distribution of memories.

Patients with schizophrenia display numerous memory impairments. Examination of autobiographical memory distribution across the life span can constrain theories of how schizophrenia affects memory. Previously, schizophrenic patients were shown to produce fewer memories from early adulthood than from childhood or the recent past (A. Feinstein, T. E. Goldberg, B. Nowlin, & D. R. Weinberger, 1998), this temporal paucity corresponding with illness onset. The current study examined this issue further using a different (noncued) method. Age-matched schizophrenic patients (n = 21) and controls (n = 21) were to freely generate 50 episodes, after which they dated these memories. Patients generated fewer memories than did controls, especially from the recent decade. When the overall lower production of memories was controlled for, the groups displayed equivalent recency effects. It was concluded that patients' paucity of memories generated from the recent decade reflects encoding or acquisition problems, which may be associated with the illness period.

Adult↗

PubMed2002

Recollection-based memory in frontotemporal dementia: implications for theories of long-term memory.

It has been convincingly demonstrated that patients with semantic dementia (the temporal variant of frontotemporal dementia) can show intact recognition memory for pictorial stimuli. As yet, the contribution made by recollective processes to this ability and the status of associated neural regions have not been investigated in the disease. Here, we used both a source monitoring paradigm and an associative memory test to evaluate the ability of patients with semantic dementia to use recollection-based memory processes, and a volumetric MRI technique to assess the extent of atrophy in the hippocampus. Although some patients showed impaired source and associative memory, many performed as well as control participants. Importantly, status of semantic knowledge, as measured by tests of comprehension and production, did not predict recollection-based memory ability. There was no significant positive correlation between recollection and volume of the hippocampus; instead, both source discrimination and associative memory correlated highly with performance on a battery of frontal lobe tests. Consistent with the view that damage to the prefrontal cortex might influence recollection performance, patients with the frontal variant of frontotemporal dementia, with atrophy largely confined to the frontal lobes, all performed at floor level on source discrimination. These results provide further compelling evidence in favour of the multiple input model of long-term memory and highlight the role of frontal lobe systems in recollection-based memory.

Aged↗

PubMedDate not supplied

Memory complaints before and after temporal lobectomy: do they predict memory performance or lesion laterality?

The relationships among self-report of memory, actual memory performance on objective tasks, and lesion laterality were examined in this longitudinal study. Right-handed adults (n = 47) with medically intractable seizures were assessed both preoperatively and 1 year after a left or right temporal lobectomy. Memory complaints remained stable or diminished postoperatively, whereas performance on material-specific memory tasks declined. Regression analyses showed that dosage of medications, seizure frequency and self-reported depression were predictive of postoperative memory complaints, although size of resection and age were not. Together, these data suggest that many patients have a positive though mistaken impression that their memory functions improved after temporal lobectomy, an impression influenced by their positive surgical outcomes. Memory complaints did not predict laterality of the lesion. Sex-laterality interactions were evident for both subjective and objective memory measures.

Adult↗

PubMed2003

CREB, memory enhancement and the treatment of memory disorders: promises, pitfalls and prospects.

The treatment of memory disorders, such as the gradual weakening of memory with age, the ravages of Alzheimer's disease and the cognitive deficits in various forms of mental retardation, may greatly benefit from a better understanding of the molecular and cellular mechanisms of memory formation. There is increasing interest in the possibility of pharmacologically enhancing learning and memory even in the absence of specific anatomically evident pathology. Substantial evidence in experimental systems ranging from molluscs to humans indicates that the cAMP response element binding protein (CREB) is a core component of the molecular switch that converts short- to long-term memory. Recent studies have greatly strengthened and refined our understanding of the role of CREB in learning and memory in mammals, in addition to providing greater insight into the molecular mechanisms of CREB regulation and function. This involvement of CREB and the upstream signalling pathways leading to its activation in learning-associated plasticity makes them attractive targets for drugs aimed at improving memory function, in both diseased and healthy individuals. However, CREB and its close relatives cAMP response element modulator and activating transcription factor-1 are ubiquitous proteins with several critical functions. This creates hurdles that the authors believe may limit the usefulness of CREB per se as a target for the development of memory-enhancing drugs, and focus on components of the upstream signalling pathways or on specific downstream targets will be required.

Amino Acid Sequence↗

PubMed2001

Short-term memory in Down syndrome: applying the working memory model.

This paper is divided into three sections. The first reviews the evidence for a verbal short-term memory deficit in Down syndrome. Existing research suggests that short-term memory for verbal information tends to be impaired in Down syndrome, in contrast to short-term memory for visual and spatial material. In addition, problems of hearing or speech do not appear to be a major cause of difficulties on tests of verbal short-term memory. This suggests that Down syndrome is associated with a specific memory problem, which we link to a potential deficit in the functioning of the 'phonological loop' of Baddeley's (1986) model of working memory. The second section considers the implications of a phonological loop problem. Because a reasonable amount is known about the normal functioning of the phonological loop, and of its role in language acquisition in typical development, we can make firm predictions as to the likely nature of the short-term memory problem in Down syndrome, and its consequences for language learning. However, we note that the existing evidence from studies with individuals with Down syndrome does not fit well with these predictions. This leads to the third section of the paper, in which we consider key questions to be addressed in future research. We suggest that there are two questions to be answered, which follow directly from the contradictory results outlined in the previous section. These are 'What is the precise nature of the verbal short-term memory deficit in Down syndrome', and 'What are the consequences of this deficit for learning'. We discuss ways in which these questions might be addressed in future work.

Down Syndrome↗

PubMed2006

Effects of age and ability on self-reported memory functioning and knowledge of memory aging.

The authors examined the effects of age and ability (as measured by education and verbal ability) on self-reported memory functioning in adulthood. In Study 1, the age and ability groups responded similarly to the Cognitive Failures Questionnaire (D. E. Broadbent, P. F. Cooper, P. Fitzgerald, & K. R. Parkes, 1982), but differences emerged when the authors examined specific items tapping prospective and retrospective memory. In Study 2, the authors found age and ability differences in self-reported memory functioning, as measured by the Memory Functioning Questionnaire (M. J. Gilewski, E. M. Zelinski, & K. W. Schaie, 1990) and in knowledge of memory aging, as measured by the Knowledge of Memory Aging Questionnaire (K. E. Cherry, R. L. West, C. M. Reese, M. P. Santa Maria, & M. Yassuda, 2000). In both studies, differences in self-reported functioning were not related to objective memory performance. In the second study, knowledge was positively related to performance. Implications for conceptions of metamemory and memory aging are considered.

Activities of Daily Living↗

PubMed2000

Distinguishing between memory illusions and actual memories using phenomenological measurements and explicit warnings.

Previous research has demonstrated that the false memory effect is robust and that false memories are essentially indistinguishable from memories for events that actually occurred. The current study used several techniques intended to eliminate false memories (source monitoring decisions, confidence ratings, remember/know judgments, and explicit warnings). A robust false memory effect was found in each experiment. However, participants were able to differentiate false memories and actual memories when using specific phenomenological tasks. The current findings provide insight into basic human memory processes.

Adult↗

PubMed2003

[Memory systems and memory disorders].

Recent cognitive models suggest that memory has a complex structure, composed of several independent systems (working memory, and four long-term memory systems: episodic memory, semantic memory, perceptual representation system, and procedural memory). Furthermore, neuropsychological studies show that a brain lesion can selectively impair some systems or some particular process in a system, while others are spared. In this theoretical context, the objective of assessment is to detect the impaired memory systems and processes as well as those, which remain intact. To do this, the clinician has to use various-tests specifically designed to assess the integrity of each memory system and process.

Humans↗

PubMed1991

Verbal short-term memory span in speech-disordered children: implications for articulatory coding in short-term memory.

One influential explanation of the development of verbal short-term memory in children argues that short-term memory capacity is a direct function of speech rate. This theory predicts that children with pathologically slow speech will show reduced verbal short-term memory capacity and will show less evidence of speech-base coding on verbal memory tasks. To test this prediction, verbal short-term memory span was assessed using a task that did not require a verbal response in 37 speech-disordered children and 37 age- and sex-matched controls (age range 4-15 years). The speech-disordered group had a significantly lower short-term memory capacity, a smaller word length effect, and reduced speech-motor activity during rehearsal periods. Covariance analyses revealed that these differences were not a function of general intellectual or motor speed differences between the groups, and that speech rate as a covariate abolished group differences in short-term memory. These results suggest that speech rate may be a causal determinant of verbal short-term memory capacity.

Adolescent↗

PubMed2000

Course of objective memory impairment in non-demented subjects attending a memory clinic and predictors of outcome.

The aim of the study was to investigate the course of objective memory impairment in non-demented subjects who attended a memory clinic and to test predictors of outcome. Non-demented subjects (N=74) were included when they were older than 40 years and had a baseline score on the delayed recall of a word learning test below the tenth percentile. Subjects with memory impairment due to known somatic or neurological causes were excluded. The subjects were reassessed after 2 and 5 years. At the 5-year follow-up, 42% of the subjects had no memory impairment, 19% of the subjects had memory impairment without dementia, and 39% of the subjects had Alzheimer type dementia (AD). Predictors at baseline of reversible memory impairment in a multivariate analysis were age, scores on the MMSE and delayed recall, and the degree of functional impairment. Predictors at baseline of AD in a multivariate analysis were age and the score on the MMSE. The apolipoprotein E genotype and the presence of depression at baseline were not predictors of outcome. The positive predictive value was 72% for reversible memory impairment and 81% for AD. Memory impairment is often reversible and therefore its presence alone is not sufficient to consider subjects as preclinically demented. Predictive accuracy can be increased by including simple measures such as age, the scores on the MMSE and delayed recall, and the degree of functional impairment.

Age Factors↗

PubMed1986

Memory assessment using the Strub-Black Mental Status Examination and the Wechsler Memory Scale.

A systematic mental status exam often can differentiate accurately patients with organic brain disease from normal persons and those with functional disorders. The present study attempts to validate the memory portion of the Strub-Black Mental Status Exam by comparing it to the Wechsler Memory Scale. Twenty-five brain-damaged and 25 routine medical patients were given Form I of the Wechsler Memory Scale and the memory portion of the Strub-Black Mental Status Exam at their hospital bedside. Results indicate significant differences in almost all scores between the brain-damaged and normal groups on both the Wechsler Memory Scale and Mental Status exam; the Mental Status Exam differentiated between groups at a higher level of significance of ANOVA and ANCOVA comparisons of total memory scores, as well as several subtests. In these samples, age, more than education, was an important factor that affected memory test performance. The Mental Status Examination appears valid for the differentiation of clinical samples and for the documentation of specific aspects of memory dysfunction in individual brain-damaged patients. This study represents a beginning step in providing normative data on components of the Strub-Black mental status examination.

Adult↗

PubMed2001

Both CD45R(low) and CD45R(high) "revertant" CD4 memory T cells provide help for memory B cells.

During a primary response to thymus dependent antigens, B cells undergo a number of qualitative changes to become memory B cells - processes that require co-stimulatory signals and cytokine help from CD4 T cells. The question of whether distinct, antigen-experienced memory CD4 T cells are subsequently needed to program memory B cells into antibody synthesis has not been clearly resolved. Using an adoptive transfer model in which memory but not naive B cells were stimulated, we evaluated CD4 T cell help using lymphocytes obtained from primed or unprimed thymectomized donors and expressing a naive (CD45R(high)) or a memory (CD45R(low)) phenotype. Memory B cells, most of which were committed to the IgG1 (Th2) subclass, could be stimulated to produce antibody using help transferred by the CD45R(high) naive subset of unprimed donors (slow onset of response), the CD45R(low) subset of 7 day primed donors (large, rapid antibody response) or by both the CD45R(low) and the CD45R(high) "revertant" subsets of 6 month primed donors. We found that antigen primed CD45R(low) CD4 T cells reverted (defaulted) with time to a CD45R(high) resting state, a change that was prevented by persisting antigen. The evidence suggests that CD4 memory T cells are partitioned into two different functional states (CD45R(high) and CD45R(low)) and that these determine the characteristics of the memory B cell response in terms of speed, size and longevity.

Animals↗

PubMed2002

Age-related changes in event-related prospective memory performance: a comparison of four prospective memory tasks.

The primary purpose of the study was to identify event-based prospective-memory tasks that provide sensitive and reliable tools for assessing effects of normal aging in prospective-memory performance. Four prospective-memory tasks were selected from the literature or were newly developed, with the tasks differing on various dimensions that, for theoretical reasons or based on previous evidence, might determine task sensitivity to age effects on prospective-memory performance: perceptual saliency of prospective target events, frequency of occurrence of prospective target events, complexity of prospective-memory instructions, and provision of feedback after prospective-memory errors. Two of the four tasks yielded large and robust age effects on prospective-memory performance. Correlational analyses suggested that these age effects on prospective-memory performance were mediated, at least in part, by a reduced ability of older adults to maintain prospective intentions in a highly activated state and not by age effects on basic mental speed alone.

Adolescent↗