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PubMed2005

Consistency of memory for emotionally arousing events: a review of prospective and experimental studies.

Although emotionally arousing events are more memorable than ordinary daily life events, the nature of memories for emotionally arousing events is widely debated. On the one hand, researchers consider memories for highly emotional events as malleable and subject to distortion, while on the other hand these memories are perceived as both indelible and consistent over the lifetime. Up till now, a systematic comparison of research findings on consistency of memory for emotional events is lacking. This paper is the first effort to summarize available studies on consistency of memory for emotionally arousing events and to address methodological limitations and suggestions for future research as well. In general, findings show that quality of the selected studies is sufficient to good, with studies with victims of assault and studies on war-exposure reaching higher quality scores than studies on flashbulb memories and experimental memory studies. Victims of assault or war-exposure tend to amplify their memories for the event, while results from flashbulb memory research and experimental research suggest that memory for emotional events is either stable or diminishes over time.

Adolescent↗

PubMed2004

Modulation of memory by insulin and glucose: neuropsychological observations in Alzheimer's disease.

Converging evidence has identified a potential association among Alzheimer's disease, glucose metabolism, insulin activity, and memory. Notably, type 2 diabetes, which is characterized by insulin resistance, may modulate the risk of Alzheimer's disease, and patients with Alzheimer's disease may have a greater risk for glucoregulatory impairments than do healthy older adults. In animal studies, it has been shown that raising blood glucose levels acutely can facilitate memory, in part, by increasing cholinergic activity, which is greatly diminished in patients with Alzheimer's disease. Other studies have confirmed that glucose administration can facilitate memory in healthy humans and in patients with Alzheimer's disease. Interestingly, glucose effects on memory appear to be modulated by insulin sensitivity (efficiency of insulin-mediated glucose disposal). Of course, the acute effects of glucose administration should be distinguished from the effects of chronic hyperglycemia (diabetes), which has been associated with cognitive impairments, at least in older adults. The relationship of insulin and memory has been more difficult to characterize. In animals, systemic insulin administration has been associated with memory deficits, likely due, in part, to hypoglycemia that occurs when exogenous insulin is not supplemented with glucose to maintain euglycemia. In healthy adults and patients with Alzheimer's disease, raising plasma insulin levels while maintaining euglycemia can improve memory; however, raising plasma glucose while suppressing endogenous insulin secretion may not improve memory, suggesting that adequate levels of insulin and glucose are necessary for memory facilitation. Clinical studies have corroborated findings that patients with Alzheimer's disease are more likely than healthy older adults to have reduced insulin sensitivity, and further suggest that apolipoprotein E genotype may modulate the effects of insulin on glucose disposal, memory facilitation, and amyloid precursor protein processing. Collectively, these findings support an association among Alzheimer's disease, impaired glucose metabolism, and reduced insulin sensitivity.

Alzheimer Disease↗

PubMed2006

Deficits in working memory in young adults with reading disabilities.

UNLABELLED: The purpose of the present study was to assess the extent to which reading disabilities (RD) in young adults are related to deficits in specific aspects of temporary storage of verbal information, namely, memory span and the central executive (CE) component of working memory. Thirty-two native Hebrew-speaking young adults with and without RD were administered a battery of memory tasks. These tasks included Digit Span Forward and Backward tests and a new version of the Token Test (TT) which is aimed at detecting subtle deficits in auditory verbal working memory. Results showed significantly poorer performance of the RD participants than the controls on the memory tests, especially on tasks that tax the CE. These findings, albeit preliminary, support the general working memory deficit hypothesis in individuals with RD, indicating that both memory span and the CE are deficient. LEARNING OUTCOMES: As a result of this activity, the reader will able to describe the different components of the verbal working memory and the debate concerning the origin of working memory deficits in individuals with reading disabilities. The reader will also be able to apply clinical suggestions as to how one might assess components of working memory.

Adult↗

PubMed2004

Children's memory for pain: overview and implications for practice.

UNLABELLED: Children's memories of painful experiences can have long-term consequences for their reaction to later painful events and their acceptance of later health care interventions. This review surveys research on children's memory for pain, emphasizing implications for clinical practice. Topics reviewed include consequences of children's memories of pain; the development of memory; differences between explicit (declarative, verbal, autobiographic) memory and implicit (nondeclarative, nonverbal) memory; and individual differences, situational, and methodologic factors affecting memories of pain. Methods to prevent the adverse consequences of remembered pain are addressed with reference to current research on editing or reframing memories. PERSPECTIVE: This review covers topics of value to clinicians providing care to children undergoing painful procedures. Specific recommendations are offered regarding the importance of acknowledging and assessing children's previous memories of painful experiences, the type of information that benefits children before and after procedures, and the most appropriate questioning strategies. It might be possible to prevent or reduce the adverse effects of memories of pain.

Adaptation, Psychological↗

PubMed2005

Memory beliefs and function in fibromyalgia patients.

OBJECTIVE: The aim of this study was to investigate memory beliefs and their relationship to actual memory function in fibromyalgia (FM) patients. METHODS: Twenty-three FM patients, 23 age- and education-matched controls, and 22 older controls completed the Metamemory in Adulthood (MIA) questionnaire, which assessed beliefs about seven aspects of memory function. Group differences on the seven scales were assessed, and scores on the capacity scale were correlated with objective memory performance. RESULTS: FM patients reported lower memory capacity and more memory deterioration than did either control group. Patients reported lower control or self-efficacy over memory, higher achievement motivation, higher strategy use, and higher anxiety about memory than age-matched controls did. Among the patients, perceived capacity, achievement motivation, and self-efficacy were significantly correlated with objective memory performance on a recall task. CONCLUSION: FM patients' complaints about memory function have some accuracy.

Achievement↗

PubMed2004

Some pitfalls in measuring memory in animals.

Because the presence or absence of memories in the brain cannot be directly observed, scientists must rely on indirect measures and use inferential reasoning to make statements about the status of memories. In humans, memories are often accessed through spoken or written language. In animals, memory is accessed through overt behaviours such as running down an arm in a maze, pressing a lever, or visiting a food cache site. Because memory is measured by these indirect methods, errors in the veracity of statements about memory can occur. In this brief paper, we identify three areas that may serve as pitfalls in reasoning about memory in animals: (1) the presence of 'silent associations', (2) intrusions of species-typical behaviours on memory tasks, and (3) improper mapping between human and animals memory tasks. There are undoubtedly other areas in which scientists should act cautiously when reasoning about the status of memory.

Animals↗

PubMed2006

The case for episodic memory in animals.

The conscious recollection of unique personal experiences in terms of their details (what), their locale (where) and temporal occurrence (when) is known as episodic memory and is thought to require a 'self-concept', autonoetic awareness/conciousness, and the ability to subjectively sense time. It has long been held that episodic memory is unique to humans, because it was accepted that animals lack a 'self-concept', 'autonoetic awareness', and the ability to 'subjectively sense time'. These assumptions are now being questioned by behavioral evidence showing that various animal species indeed show behavioral manifestations of different features of episodic memory such as, e.g. 'metacognition', 'conscious recollection' of past events, 'temporal order memory', 'mental time travel' and have the capacity to remember personal experiences in terms of what happened, where and when. The aim of this review is to provide a comprehensive overview on the current progress in attempts to model different prerequisites and features of human episodic memory in animals and to identify possible neural substrates of animal episodic memory. The literature covered includes behavioral and physiological studies performed with different animal species, such as non-human primates, rodents, dolphins and birds. The search for episodic memory in animals has forced researchers to define objective behavioral criteria by which different features of episodic memory can be operationalized experimentally and assessed in both animals and humans. This is especially important because the current definition of episodic memory in terms of mentalistic constructs such as 'self', 'autonoetic awareness/consciousness', and 'subjectively sensed time', not only hinders animal research on the neurobiology of episodic memory but also research with healthy human subjects as well as neuropsychiatric patients with impaired language or in children with less-developed verbal abilities.

Animals↗

PubMed2006

Investigating the functional interaction between semantic and episodic memory: convergent behavioral and electrophysiological evidence for the role of familiarity.

Throughout our lives we acquire general knowledge about the world (semantic memory) while also retaining memories of specific events (episodic memory). Although these two forms of memory have been dissociated on the basis of neuropsychological data, it is clear that they typically function together during normal cognition. The goal of the present study was to investigate this interaction. One influence of semantic memory on episodic retrieval is 'Levels Of Processing'; recognition is enhanced when stimuli are processed in a semantically meaningful way. Studies examining this semantic processing advantage have largely concluded that semantic memory augments episodic retrieval primarily by enhancing recollection. The present study provides strong evidence for an alternative relationship between semantic and episodic memory. We employed a manipulation of the semantic coherence of to-be-remembered information (semantically related vs. unrelated word pairs) during an associative recognition memory test. Results revealed that associative recognition is significantly enhanced for semantically coherent material, and behavioral estimates (using the process dissociation procedure) demonstrated concomitant changes in the contribution of familiarity to retrieval. Neuroimaging data (event-related potentials recorded at test) also revealed a significant increase in familiarity based retrieval. The electrophysiological correlate of familiarity (the mid-frontal ERP old/new effect) was larger for semantically related compared to unrelated word pairs, but no difference was present in the electrophysiological correlate of recollection (the left parietal old/new effect). We conclude that semantic memory and episodic memory do indeed interact in normal functioning, and not only by modulating recollection, but also by enhancing familiarity.

Adolescent↗

PubMed2006

The multi-component model of working memory: explorations in experimental cognitive psychology.

There are a number of ways one can hope to describe and explain cognitive abilities, each of them contributing a unique and valuable perspective. Cognitive psychology tries to develop and test functional accounts of cognitive systems that explain the capacities and properties of cognitive abilities as revealed by empirical data gathered by a range of behavioral experimental paradigms. Much of the research in the cognitive psychology of working memory has been strongly influenced by the multi-component model of working memory [Baddeley AD, Hitch GJ (1974) Working memory. In: Recent advances in learning and motivation, Vol. 8 (Bower GA, ed), pp 47-90. New York: Academic Press; Baddeley AD (1986) Working memory. Oxford, UK: Clarendon Press; Baddeley A. Working memory: Thought and action. Oxford: Oxford University Press, in press]. By expanding the notion of a passive short-term memory to an active system that provides the basis for complex cognitive abilities, the model has opened up numerous questions and new lines of research. In this paper we present the current revision of the multi-component model that encompasses a central executive, two unimodal storage systems: a phonological loop and a visuospatial sketchpad, and a further component, a multimodal store capable of integrating information into unitary episodic representations, termed episodic buffer. We review recent empirical data within experimental cognitive psychology that has shaped the development of the multicomponent model and the understanding of the capacities and properties of working memory. Research based largely on dual-task experimental designs and on neuropsychological evidence has yielded valuable information about the fractionation of working memory into independent stores and processes, the nature of representations in individual stores, the mechanisms of their maintenance and manipulation, the way the components of working memory relate to each other, and the role they play in other cognitive abilities. With many questions still open and new issues emerging, we believe that the multicomponent model will continue to stimulate research while providing a comprehensive functional description of working memory.

Brain↗

PubMed2005

Different types of environmental enrichment have discrepant effects on spatial memory and synaptophysin levels in female mice.

Environmental enrichment paradigms that incorporate cognitive stimulation, exercise, and motor learning benefit memory and synaptic plasticity across the rodent lifespan. However, the contribution each individual element of the enriched environment makes to enhancing memory and synaptic plasticity has yet to be delineated. Therefore, the current study tested the effects of three of these elements on memory and synaptic protein levels. Young female C57BL/6 mice were given 3h of daily exposure to either rodent toys (cognitive stimulation) or running wheels (exercise), or daily acrobatic training for 6 weeks prior to and throughout behavioral testing. Controls were group housed, but did not receive enrichment. Spatial working and reference memory were tested in a water-escape motivated radial arm maze. Levels of the presynaptic protein synaptophysin were then measured in frontoparietal cortex, hippocampus, striatum, and cerebellum. Exercise, but not cognitive stimulation or acrobat training, improved spatial working memory relative to controls, despite the fact that both exercise and cognitive stimulation increased synaptophysin levels in the neocortex and hippocampus. These data suggest that exercise alone is sufficient to improve working memory, and that enrichment-induced increases in synaptophysin levels may not be sufficient to improve working memory in young females. Spatial reference memory was unaffected by enrichment. Acrobat training had no effect on memory or synaptophysin levels, suggesting a minimal contribution of motor learning to the mnemonic and neuronal benefits of enrichment. These results provide the first evidence that different elements of the enriched environment have markedly distinct effects on spatial memory and synaptic alterations.

Animals↗

PubMed2006

Influence of cholinergic system modulators on morphine state-dependent memory of passive avoidance in mice.

Memories are shown to be impaired in mice during step-down passive avoidance tasks with substantial residual effects lasting as long as 24 h after the pre-training administration of morphine. Administration of the same dose of morphine as a pre-test treatment restored memory. Since the cholinergic system has been reported to be involved in several actions of morphine, e.g.: modulation of memory and analgesia, we have investigated the part played by cholinergic modulator drugs, on the memory recall in mice. The locomotor activity of animals was studied as well. Administration of either atropine, a peripheral-central muscarinic antagonist, or mecamylamine, a peripheral-central nicotinic antagonist, failed to alter memory themselves, but significantly prevented morphine-induced memory recall following co-administration with morphine. Neither hexamethonium, a peripheral nicotinic antagonist, nor neostigmine, a peripheral anticholinesterase, showed intrinsic activity or a significant change in morphine-induced memory recall. Finally, physostigmine, a peripheral-central anticholinesterase, not only induced memory recall itself, but also increased morphine-induced retrieval. Memory recall of the step-down passive avoidance task following drug combinations was not related to locomotor activity changes. Thus, morphine-induced memory recall appears to be influenced by central cholinergic activity.

Animals↗

PubMed2006

Associations between olfactory identification and verbal memory in patients with schizophrenia, first-degree relatives, and non-psychiatric controls.

OBJECTIVE: Olfactory identification deficits and verbal memory impairments may represent trait markers for schizophrenia. The aims of this study were to: (1) assess olfactory identification in patients, first-degree relatives, and non-psychiatric controls, (2) determine differences in verbal memory functioning in these three groups, and (3) study correlations between olfactory identification and three specific verbal memory domains. METHOD: A total of 106 participants-41 patients with schizophrenia or related disorders, 27 relatives, and 38 controls-were assessed with the University of Pennsylvania Smell Identification Test (UPSIT) and the Wechsler Memory Scale-Third Edition. Linear mixed models, accounting for clustering within families and relevant covariates, were used to compare scores across groups and to examine associations between olfactory identification ability and the three verbal memory domains. RESULTS: A group effect was apparent for all four measures, and relatives scored midway between patients and controls on all three memory domains. UPSIT scores were significantly correlated with all three forms of verbal memory. Age, verbal working memory, and auditory recognition delayed memory were independently predictive of UPSIT scores. CONCLUSIONS: Impairments in olfactory identification and verbal memory appear to represent two correlated risk markers for schizophrenia, and frontal-temporal deficits likely account for both impairments.

Adult↗

PubMed2004

Nonverbal memory functioning following right anterior temporal lobectomy: a meta-analytic review.

PURPOSE: Studies investigating nonverbal memory functioning following right anterior temporal lobectomy (RATL) in patients with intractable temporal lobe epilepsy have resulted in conflicting findings, as nonverbal memory deficits have been reported for some, but not all patients. To examine the association between nonverbal memory deficits and RATL, the present study employed meta-analytic principles in a quantitative review of the literature. METHODS: Thirteen studies, reporting pre- and postoperative nonverbal memory performance for a total of 324 RATL patients, were identified. Effect sizes were calculated to measure the extent of nonverbal memory deficit in patients following RATL. Additionally, effect sizes for primary studies comprising a common dependent variable were combined using standard meta-analytic procedures. RESULTS: Of the 22 dependent variables utilized to assess nonverbal memory, 14 indicated postoperative declines in functioning while 8 demonstrated postoperative improvements in performance. All resultant effect sizes were relatively small. Mean effect sizes calculated for dependent variables used in multiple studies identified the Warrington Recognition Memory Test for Faces as the only nonverbal memory measure which produced consistent results. CONCLUSIONS: Overall, the collective findings demonstrate the inability of the current research to provide any consistent evidence as to the nature of nonverbal memory outcome following RATL. Problems with nonverbal memory measures are discussed and suggestions for future research are proposed.

Anterior Temporal Lobectomy↗

PubMed2006

Memory performance during the intracarotid amobarbital procedure and neuropsychological assessment in medial temporal lobe epilepsy: the limits of material specificity.

We investigated the relationship between material-specific memory performance elicited during the Wada test, or intracarotid amobarbital procedure (IAP), and classic neuropsychological assessment in 89 surgical candidates with refractory medial temporal lobe epilepsy (MTLE). The neuropsychological battery included measures of simple and complex verbal and visual memory, whereas the IAP material consisted of verbal and dually encodable stimuli. Neuropsychological testing revealed that reduced verbal memory performance was associated with left-sided MTLE, whereas visual memory tasks revealed no differences between patients with left-sided and right-sided MTLE. During IAP, memory performance was worse with the ipsilesional hemisphere, regardless of lesion side. Most importantly, performance on verbal memory tests was significantly, but moderately, correlated with left hemispheric IAP performance, indicating that memory tasks using verbal material are a valid marker of left hemispheric integrity in left language-dominant MTLE patients and significantly predict left hemispheric memory performance during IAP. In contrast, performance on classic visual memory tests is unrelated to right hemispheric IAP performance, suggesting that the currently used visual memory stimuli do not reflect right hemispheric sensitivity.

Adult↗

PubMed2003

Repeated checking causes memory distrust.

This paper attempts to explain why in obsessive-compulsive disorder (OCD) checkers distrust in memory persists despite extensive checking. It is argued that: (1) repeated checking increases familiarity with the issues checked; (2) increased familiarity promotes conceptual processing which inhibits perceptual processing; (3) inhibited perceptual processing makes recollections less vivid and detailed and finally; (4) reduction in vividness and detail promotes distrust in memory. An interactive computer animation was developed in which participants had to perform checking rituals on a virtual gas stove. Two separate experiments were carried out with n=39 (Experiment I) and n=40 (Experiment II) healthy participants. In both studies, the control group and the experimental group were given the same pre-test and post-test on the virtual gas stove. In between, the experimental group engaged in 'relevant checking', i.e. checking the gas stove, while the control group engaged in 'irrelevant checking', i.e. checking virtual light bulbs. In both experiments there were powerful effects of repeated 'relevant checking': while actual memory accuracy remained unaffected, the vividness and detail of the recollections were greatly reduced. Most pertinently, in both experiments relevant checking undermined confidence in memory. No such effects were observed in the control group. One might argue that the pre-test/post-test design may have made the control group anticipate a memory assessment at the post-test and that this artifact made them relatively alert producing memory confidence at post test that was artificially high. A third experiment was carried out (n=2 x 20) in which no pre-test was given while, other than that, Experiment III was identical to the first two experiments. Results confirmed earlier findings: compared to the irrelevant checking control group, recollections in the relevant checking group were non-vivid, non-detailed while confidence in memory was low. The theory and data suggest an answer to the question 'why memory distrust persists despite repetitive checking'. In people who check extensively, memory distrust may persist as a result of repetitive checking. OCD checking may be motivated by the wish to reduce uncertainty, but checking appears to be a counter-productive safety strategy. Rather than reducing doubt, checking fosters doubt and ironically increases meta-memory problems.

Adult↗

PubMed1998

Subjective memory evaluations in patients with focal frontal, diencephalic, and temporal lobe lesion.

This paper examines subjective memory evaluations and their correlates in patients with focal frontal, diencephalic, or temporal lobe lesions. Although all patient groups showed significantly lower subjective memory evaluations than healthy subjects, the temporal lobe group rated themselves significantly lower than the frontal lobe or diencephalic groups despite comparable severity of amnesia, implying more severely impaired 'insight' in the latter two groups. There was a 'temporal gradient' such that patients rated their memory for 'old' (premorbid) items better than their memory for 'new' (recent) or prospective items. As in previous studies, subjective memory evaluations were not correlated with measures of 'objective' anterograde memory performance, but the present study suggests that subjective evaluations are not randomly determined. It seemed to be the site of lesion (frontal and/or diencephalic), rather than underlying aetiology, which produced a particularly severe loss of 'insight'. Whether the earliest remote or autobiographical memories were preserved or not appeared to be an important correlate of current subjective memory evaluations, and patients who had been memory-disordered for longer were more likely to evaluate their memory as poor than those with a more recent onset.

Adult↗

PubMed1979

Material specific serial memory deficit in adolescent dyslexics.

The present experiment was concerned with an assessment of possible serial, as opposed to general, memory deficit in dyslexia. Previous studies had consistently confounded general and serial memory assessments. Fifteen specifically dyslexic adolescents and 15 normal-reading controls were administered four separate memory tasks. In the general memory for verbal material task they were shown 20 words, each for three seconds, and were then given a deck of 40 word cards and required to pick out the 20 words just seen. In the serial memory version of the verbal task they were again shown 20 words and subsequently required to reproduce the order in which they had been shown. Two comparable (general and serial) procedures were also administered using faces as the to-be-remembered materials. Results showed comparable performances of the dyslexics and controls on both versions of the face memory task and on the general memory version of the words task. On the serial reproduction version of the verbal task, however, dyslexics were found to be significantly impaired relative to controls. Thus, adolescent dyslexics appear to have a memory impairment which is specific for both type of material (verbal) and type of memory (serial). The results are compatible with Orton's (1937) speculation regarding "sequecing" and "memory" in dyslexia and with the view that the defect resides within the neuropsychological processes of the language-dominant hemisphere.

Adolescent↗

PubMed2001

Varieties of human spatial memory: a meta-analysis on the effects of hippocampal lesions.

The current meta-analysis included 27 studies on spatial-memory dysfunction in patients with hippocampal damage. Each study was classified on the basis of the task that was used, i.e., maze learning, working memory, object-location memory, or positional memory. The overall results demonstrated impairments on all spatial-memory tasks. Clear differences in effect size were found between positional memory on the one hand and maze learning, object-location memory, and working memory on the other hand. Lateralization was found only on maze learning and object-location memory. These findings clearly indicate that specific aspects of spatial memory can be affected in various degrees in patients with hippocampal lesions. Moreover, these results strongly support the notion that the hippocampus is important in the processing of metric positional information, probably in the form of an allocentric cognitive map.

Animals↗