SEARCH · PubMed Health

Results for “memory”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,369 records · Page 76Linked to original sources

PubMedDate not supplied

Memory function in childhood epilepsy syndromes.

OBJECTIVE: Children with epilepsy are at risk of specific cognitive deficits. We aimed to compare and characterize the memory function of children with childhood absence epilepsy (CAE), frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE). METHODS: Epilepsy syndrome was identified by clinical data, seizure semiology, interictal and ictal electroencephalogram (EEG). Seventy children aged 6-18 years with CAE, FLE or TLE had neuropsychological assessment including memory function. After adjusting for epilepsy variables, neuropsychological results of the syndrome groups and normative data were compared. RESULTS: Children from all three syndrome groups were at risk of memory difficulties. The duration of epilepsy correlated negatively with memory function. Children with TLE had the worst memory function, significantly lower in verbal memory tasks than children with CAE (P = 0.02) and children with FLE (P = 0.01). The performance of children with TLE was significantly below the normed mean across all verbal and most visual tasks. Compared to the normed means, children with FLE had results that were statistically lower in some verbal and visual tasks, and children with CAE were lower in two visual tasks only. CONCLUSIONS: This study demonstrates memory dysfunction in three common childhood epilepsy syndromes. Children with TLE had the greatest impairment, children with FLE had memory difficulties not previously reported, and children with CAE had subtle memory deficits. Qualitative differences were also evident. Longer duration of intractable epilepsy was associated with reduced memory ability. Memory function and its potential impact on academic achievement are vital considerations when managing children with epilepsy.

Adolescent↗

PubMed1994

The development of memory and processing capacity.

The assumption of some developmental theories that short-term memory is the workspace of higher cognitive processes, and consequently that span measures processing capacity, is claimed to be inconsistent with the working memory literature. 4 experiments, using children aged 5 to 12 years, contrast this theory with a model in which short-term memory and the processing space component of working memory are at least partly distinct. Experiments 1 and 2 varied processing load, holding duration constant. The processing load manipulation had little effect on recall of a short-term memory preload. Experiments 3 and 4 failed to support the prediction that the greater processing efficiency of older children would be associated with slower loss of information from short-term memory. Although counting and rehearsal rates increased with age, and correlated with span, they did not predict the rate of loss of memory preload due to intervening counting. The data suggest that effects obtained with short-term memory span do not provide clear indications of overall working memory development, because short-term memory span and the processing space component of working memory entail distinct systems.

Age Factors↗

PubMed1995

Autobiographical memory and chronic pain.

The influence of chronic pain on the recall of autobiographical memories of pain and non-pain events was examined. Eleven chronic pain patients and 11 age- and sex-matched control subjects retrieved autobiographical memories to neutral and pain-related cue words. Patients and controls retrieved equal numbers of memories, but pain subjects retrieved more memories incorporating elements of physical pain. Analysis of the content of these memories revealed that patients and controls recalled equal numbers of memories of themselves and other people in acute pain and that the difference observed was attributable to the pain patients recalling memories of themselves in chronic pain. Memories of pain were recalled significantly faster than non-pain memories. The results are discussed with reference to the possible biasing effects of pain state on memory and the schematic processing of pain memories.

Adolescent↗

PubMed1997

Medial temporal structures relate to memory impairment in Alzheimer's disease: an MRI volumetric study.

OBJECTIVES: Memory impairment is not only the earliest clinical symptom but a central and prominent feature throughout the course of Alzheimer's disease. Alzheimer related pathological alterations in the medial temporal structures may account for the memory impairments in patients with Alzheimer's disease. The aim of this study was to elucidate the role of the medial temporal structures in memory impairment caused by Alzheimer's disease. METHODS: Using high resolution MRI and a semiautomated image analysis technique, volumes of the medial temporal structures (amygdaloid complex, hippocampal formation, subiculum, and parahippocampal gyrus) were measured, and correlations between atrophy of each structure and memory dysfunction in patients with Alzheimer's disease were examined. RESULTS: Patients with Alzheimer's disease showed poor performance on verbal and non-verbal memory tests, and MRI volumetry showed a significant volume reduction of the medial temporal lobe structures. Volumes of the amygdaloid complex and of the subiculum correlated with memory performance. Stepwise regression analyses disclosed that the volume of the right amygdaloid complex specifically predicted visual memory function and to some extent verbal memory function, and that the volume of the left subiculum specifically predicted verbal memory function. Atrophy of the hippocampus did not predict severity of memory impairment. CONCLUSIONS: The presence of perihippocampal damage involving the amygdala proper, its surrounding cortex, and the subiculum further increased the severity of memory impairment attributable to hippocampal damage in Alzheimer's disease.

Adult↗

PubMed2005

In search of memory traces.

The key issue in analyzing brain substrates of memory is the nature of memory traces, how memories are formed, stored, and retrieved in the brain. In order to analyze mechanisms of memory formation it is first necessary to find the loci of memory storage, the classic problem of localization. Various approaches to this issue are reviewed. A particular strategy is proposed that involves a number of different techniques (electrophysiological recording, lesions, electrical stimulation, pathway tracing) to identify the essential memory trace circuit for a given form of learning and memory. The methods of reversible inactivation can be used to localize the memory traces within this circuit. Using classical conditioning of eye blink and other discrete responses as a model system, the essential memory trace circuit is identified, the basic memory trace is localized (to the cerebellum), and putative higher-order memory traces are characterized in the hippocampus.

Affect↗

PubMed2001

Frontal eye field sends delay activity related to movement, memory, and vision to the superior colliculus.

Many neurons within prefrontal cortex exhibit a tonic discharge between visual stimulation and motor response. This delay activity may contribute to movement, memory, and vision. We studied delay activity sent from the frontal eye field (FEF) in prefrontal cortex to the superior colliculus (SC). We evaluated whether this efferent delay activity was related to movement, memory, or vision, to establish its possible functions. Using antidromic stimulation, we identified 66 FEF neurons projecting to the SC and we recorded from them while monkeys performed a Go/Nogo task. Early in every trial, a monkey was instructed as to whether it would have to make a saccade (Go) or not (Nogo) to a target location, which permitted identification of delay activity related to movement. In half of the trials (memory trials), the target disappeared, which permitted identification of delay activity related to memory. In the remaining trials (visual trials), the target remained visible, which permitted identification of delay activity related to vision. We found that 77% (51/66) of the FEF output neurons had delay activity. In 53% (27/51) of these neurons, delay activity was modulated by Go/Nogo instructions. The modulation preceded saccades made into only part of the visual field, indicating that the modulation was movement-related. In some neurons, delay activity was modulated by Go/Nogo instructions in both memory and visual trials and seemed to represent where to move in general. In other neurons, delay activity was modulated by Go/Nogo instructions only in memory trials, which suggested that it was a correlate of working memory, or only in visual trials, which suggested that it was a correlate of visual attention. In 47% (24/51) of FEF output neurons, delay activity was unaffected by Go/Nogo instructions, which indicated that the activity was related to the visual stimulus. In some of these neurons, delay activity occurred in both memory and visual trials and seemed to represent a coordinate in visual space. In others, delay activity occurred only in memory trials and seemed to represent transient visual memory. In the remainder, delay activity occurred only in visual trials and seemed to be a tonic visual response. In conclusion, the FEF sends diverse delay activity signals related to movement, memory, and vision to the SC, where the signals may be used for saccade generation. Downstream transmission of various delay activity signals may be an important, general way in which the prefrontal cortex contributes to the control of movement.

Animals↗

PubMed2001

Primate rhinal cortex participates in both visual recognition and working memory tasks: functional mapping with 2-DG.

The rhinal cortex in the medial temporal lobe has been implicated in object recognition memory tasks and indeed is considered to be the critical node in a visual memory network. Previous studies using the 2-deoxyglucose method have shown that thalamic and hippocampal structures thought to be involved in visual recognition memory are also engaged by spatial and object working memory tasks in the nonhuman primate. Networks engaged in memory processing can be recognized by analysis of patterns of activation accompanying performance of specifically designed tasks. In the present study, we compared metabolic activation of the entorhinal and perirhinal cortex during the performance of three working memory tasks [delayed response (DR), delayed alternation (DA), and delayed object alternation (DOA)] to that induced by a standard recognition memory task [delayed match-to-sample (DMS)] and a sensorimotor control task in rhesus monkeys. A region-of-interest analysis revealed elevated local cerebral glucose utilization in the perirhinal cortex in animals performing the DA, DOA, and DMS tasks, and animals performing the DMS task were distinct in showing a strong focus of activation in the lateral perirhinal cortex. No significant differences were evident between groups performing memory and control tasks in the entorhinal cortex. These findings suggest that the perirhinal cortex may play a much broader role in memory processing than has been previously thought, encompassing explicit working memory as well as recognition memory.

Animals↗

PubMed2006

Poststroke memory function in nondemented patients: a systematic review on frequency and neuroimaging correlates.

BACKGROUND AND PURPOSE: Poststroke memory dysfunction is a prerequisite for the diagnosis of poststroke dementia. This diagnosis is made within months after a stroke, apparently assuming a relatively stable course of the poststroke memory function. Clinical experience added to anecdotal evidence from the literature suggests that poststroke memory function may be reversible. The aim of the present study was to systematically review the available data on the time course of poststroke memory function in nondemented stroke survivors. In addition, we wanted to investigate the role of (pre-)stroke characteristics on poststroke memory function. METHODS: We performed systematic literature search of PubMed with the following medical subject heading terms: memory and stroke. The search strategy yielded 798 articles of which 65 fulfilled our inclusion criteria and went on to the data extraction stage. RESULTS: Five studies reported the prevalence of poststroke memory dysfunction at different poststroke intervals. The prevalence of poststroke memory dysfunction varied from 23% to 55% 3 months poststroke, which declined from 11% to 31% 1 year poststroke. Larger stroke volume, prestroke medial temporal lobe atrophy, and white matter lesions were related with decreased poststroke memory function. CONCLUSIONS: Not all patients with poststroke memory dysfunction 3 months after a stroke had memory dysfunction 1 year poststroke. Consequently, not all criteria for the dementia diagnosis were fulfilled any more. This may indicate that poststroke dementia may be reversible in a substantial proportion of patients with stroke. Preferably, standardized reassessment of cognitive function should be performed in each patient diagnosed with poststroke dementia.

Atrophy↗

PubMed2000

Activity in human frontal cortex associated with spatial working memory and saccadic behavior.

We examined, with event-related fMRI, two hypotheses about the organization of human working memory function in frontal cortex: (1) that a region immediately anterior to the frontal eye fields (FEF) (superior frontal cortex, SFC) is specialized for spatial working memory (Courtney, et al., 1998); and (2) that dorsolateral prefrontal cortex (PFC) plays a privileged role in the manipulation of spatial stimuli held in working memory (Owen, et al., 1996; Petrides 1994). Our delayed-response task featured 2-D arrays of irregularly arranged squares that were highlighted serially in a random sequence. The Forward Memory condition required maintenance of the spatio-temporal sequence, the Manipulate Memory condition required reordering this sequence into a new spatially defined order, the Guided Saccade condition required saccades to highlighted squares in the array, but no memory, and the Free Saccade condition required self-paced, horizontal saccades. The comparison of fMRI signal intensity associated with 2-D saccade generation (Guided Saccades) versus fMRI signal intensity associated with the delay period of the working memorials condition revealed no evidence for greater working memory-related activity than saccade-related activity in SFC in any individual subject, nor at the level of the group, and greater 2-D saccade than delay-period activity in three of five subjects. These results fail to support the hypothesis that spatial working memory-related activity is represented preferentially in a region of SFC anterior to the FEF (Courtney, et al., 1998). The comparison of maintenance versus manipulation of spatio-temporal information in working memory revealed significantly greater activity associated with the latter in dorsolateral PFC, but not in ventrolateral PFC or in SFC. These results suggest that the delay-related function of SFC is limited to the maintenance of spatial information, and that this region does not support the nonmnemonic executive control functions supported by dorsolateral PFC. These results also indicate that the preferential recruitment of dorsolateral PFC for the manipulation of information held in working memory applies to tasks employing spatial stimuli, as well as to tasks employing verbal stimuli (D'Esposito, et al., 1999); Petrides et al., 1993; Postle et al., 1999).

Acoustic Stimulation↗

PubMed2007

Selective attention supports working memory maintenance by modulating perceptual processing of distractors.

Selective attention has been shown to bias sensory processing in favor of relevant stimuli and against irrelevant or distracting stimuli in perceptual tasks. Increasing evidence suggests that selective attention plays an important role during working memory maintenance, possibly by biasing sensory processing in favor of to-be-remembered items. In the current study, we investigated whether selective attention may also support working memory by biasing processing against irrelevant and potentially distracting information. Event-related potentials (ERPs) were recorded while subjects (n = 22) performed a delayed-recognition task for faces and shoes. The delay period was filled with face or shoe distractors. Behavioral performance was impaired when distractors were congruent with the working memory domain (e.g., face distractor during working memory for faces) relative to when distractors were incongruent with the working memory domain (e.g., face distractor during shoe working memory). If attentional biasing against distractor processing is indeed functionally relevant in supporting working memory maintenance, perceptual processing of distractors is predicted to be attenuated when distractors are more behaviorally intrusive relative to when they are nonintrusive. As such, we predicted that perceptual processing of distracting faces, as measured by the face-sensitive N170 ERP component, would be reduced in the context of congruent (face) working memory relative to incongruent (shoe) working memory. The N170 elicited by distracting faces demonstrated reduced amplitude during congruent versus incongruent working memory. These results suggest that perceptual processing of distracting faces may be attenuated due to attentional biasing against sensory processing of distractors that are most behaviorally intrusive during working memory maintenance.

Adolescent↗

PubMed2003

The relation between memory of the traumatic event and PTSD: evidence from studies of traumatic brain injury.

OBJECTIVE: This paper focuses on the relation between memory and posttraumatic stress disorder (PTSD). More specifically, it addresses the debate regarding the role of memory of the traumatic event in the development of PTSD. Traumatic brain injury (TBI) is used as a naturally occurring model for traumatic exposure that is often associated with memory impairment. METHOD: We present a critical review of the literature on studies assessing the relation between TBI and PTSD, with a focus on memory of the traumatic event as a critical factor. We also discuss results from recent studies conducted by our group. RESULTS: The literature review offers an inconclusive picture wherein a significant proportion of the studies indicate that PTSD and TBI are mutually exclusive, especially in individuals who exhibit lack of memory for the traumatic event. This finding supports the possibility that lack of memory may protect against the development of PTSD. However, some studies show that PTSD does occur in patients with head injury, suggesting that PTSD may develop in TBI survivors--even in those who cannot remember the traumatic event. Generally speaking, though, the overall balance of the findings (including our own findings) seems to support the possibility that, in subjects with TBI, impaired memory of the traumatic event is associated with reduced prevalence of PTSD. CONCLUSIONS: The suggestion that amnesia regarding the traumatic event may protect against the development of PTSD has both theoretical and practical importance. This review focused on the case of traumatic brain injury as a model for impaired memory for the traumatic event. However, it still remains to be proven that the conclusions based on these findings are generalizable beyond the case of TBI. While some patients with posttraumatic amnesia do develop PTSD despite lack of memory for the traumatic event, the majority of those who lack memory for the event seem to be protected from developing the disorder. Nevertheless, based on this assumption, we suggest that pharmacologic disruption of newly acquired--or even old--traumatic memories, which has been shown to be possible in animals, might therapeutically benefit trauma survivors.

Brain Injuries↗

PubMed2007

Inability of memory T cells to induce graft-versus-host disease is a result of an abortive alloresponse.

Several groups, including our own, have independently demonstrated that effector memory T cells from non-alloantigen-primed donors do not cause graft-versus-host disease (GVHD). In the current study, we further investigated whether this approach could be extended to all memory T cells, and we studied the underlying mechanisms. Neither total memory T cells nor purified central memory T cells were able to induce GVHD. Memory T cells were at least 3-log less potent than bulk T cells in mediating GVHD. As expected, memory T cells failed to elicit cytotoxicity and proliferated poorly against alloantigens in standard 5-day mixed-lymphocyte cultures. However, the proliferative responses of memory T cells were more comparable with those of bulk and naive T cells when the culture time was shortened. Moreover, the frequencies of IL-2-secreting cells measured by 42-hour enzyme-linked immunosorbent spot (ELISPOT) assay were similar among naive, memory, and bulk T cells. These data indicated that memory T cells are able to respond to alloantigens initially but fail to develop to full potential. The abortive immune response, which was mediated by non-alloantigen-specific memory T cells in response to alloantigens, may explain why memory T cells from unprimed and non-alloantigen-primed donors could not induce GVHD.

Animals↗

PubMed1999

Relations among indexes of memory disturbance and depression in patients with Lyme borreliosis.

This study examined the relation between complaints of memory disturbance and measures of mood and memory functioning in 55 patients with serological evidence of late-stage Lyme Borreliosis (LB). Patients completed the Self-Ratings of Memory Questionnaire (SRMQ) and the Beck Depression Inventory. Memory functioning was assessed with the California Verbal Learning Test. Depressed patients exhibited more frequent complaints of memory disturbance on the SRMQ, although their pattern of responses did not differ from nondepressed patients. There was a significant correlation between subjective memory ratings and self-reported depression (Spearman rho = -.57, p < .001). No relation was observed between subjective memory ratings and objective memory performance. The results indicate subjective complaints of more severe memory disturbance in patients with LB and depression. Particular attention should be paid to the assessment of depression and subjective symptoms of memory disturbance when administering neuropsychological tests of memory functioning in patients with LB.

Adult↗

PubMed1999

Selective decline in memory function among healthy elderly.

OBJECTIVE: To use longitudinally acquired data to establish whether aging is associated with memory decline. BACKGROUND: Memory loss is one of the most frequent complaints among the elderly. Nevertheless, age-related memory decline remains controversial in large part because it has been established with cross-sectional studies. METHODS: A total of 212 community-based healthy people were followed prospectively and evaluated annually with a neuropsychological battery testing memory and other cognitive domains. To control for the learning effect-the improvement in test performance associated with repeated exposure-longitudinal performance was compared between two age groups. RESULTS: The older age group displayed a relative decline in memory performance with time. In contrast to memory, a relative age-related decline was not observed in tests of language, visuospatial ability, and abstract reasoning. Furthermore, within the memory domain, age-related decline was restricted to a specific aspect of memory, manifesting only in a measure sensitive to the acquisition and early retrieval of new information, and not in a measure of memory retention. This profile of age-related cognitive decline anatomically localizes to the hippocampal formation. CONCLUSION: This study establishes age-related memory decline using longitudinal data, and shows that this decline does not occur diffusely across multiple cognitive domains. Both early AD as well as non-AD processes likely contribute to age-related memory decline, and continued follow-up may reveal distinguishing features between these two.

Aged↗

PubMed2006

HRT and everyday memory at menopause: a comparison of two samples of mid-aged women.

Research on the effect of hormone replacement therapy (HRT) on memory in mid-aged women is equivocal although findings indicate that oestrogen may enhance verbal memory. Mood may mediate the relationship between HRT and memory. This study examined the effect of HRT on mood and everyday memory in two samples of women between ages 40 and 60 years. In the cross-sectional comparison (N = 124), HRT users performed significantly better on tests of everyday and verbal memory. A within-woman comparison of 17 women showed that everyday memory, working memory, and delayed verbal memory improved after 3 months of HRT use. The improvement in memory was not mediated by mood. These results suggest that any effect of HRT on mood may be short-term but that some aspects of everyday memory are enhanced, particularly verbal memory. The development of the everyday.

Adult↗

PubMed2000

The timing, triggers and qualities of recovered memories in therapy.

OBJECTIVES: To report descriptive data on memory recovery of traumatic material including: degree of prior amnesia, triggers to recovery, qualities of the memory and length of time taken to recover different types of memory. DESIGN: British Psychological Society practitioners who reported having clients with recovered memories in a previous large-scale survey were contacted for an indepth interview. They each provided information on up to three such clients. METHODS: From telephone interviews with 108 therapists, we elicited 236 detailed accounts of clients recovering a traumatic memory. Interviews were semistructured with investigator-based ratings. RESULTS: The degree of amnesia varied widely according to therapists: some clients had prior total amnesia, others a prior vague sense or suspicion, and others prior partial memories. Time in therapy before first recall was longer for memories involving child sexual abuse than for memories of other traumas. The majority of the memories, but not all, were similar to those reported by patients with post-traumatic stress disorder: they were fragmented, accompanied by high levels of emotion, and experienced as a reliving of the original event. CONCLUSIONS: On the basis of current understanding of memory processes, several mechanisms may be needed to explain all the data, including disruptions to the encoding and retrieval of traumatic events and errors in the attribution of the source of specific memories. It will be important to confirm these findings by interviewing clients themselves.

Adult↗

PubMed2002

Specificity of autobiographical memories in depression: an analysis of retrieval processes in a think-aloud task.

OBJECTIVES: According to J. M. G. Williams' (1996) concept of mnemonic interlock, the autobiographical memory retrieval of depressed patients tends to become deadlocked in a process characterized by iterative retrievals of overgeneral categoric memories. Following this concept, the study investigated whether depressed patients show consecutive retrievals of categoric memories. DESIGN: Depressed and control participants were compared regarding the temporal progression of memory retrievals in a think-aloud cued autobiographical memory task. METHOD: Depressed out-patients (N = 15) and control participants (N = 15) were given cue words and asked to verbalize all thoughts while remembering details of an autobiographical event during a period of 2 min. Streams-of-consciousness were analysed regarding the number of different events. Event descriptions were judged as categoric, extended or specific. RESULTS: Compared to control participants, depressed participants produced significantly higher total numbers of categoric memories. Depressed participants differed from control participants regarding the number of consecutive categoric memories following an initial categoric memory but not following an initial specific memory. CONCLUSION: Consistent with the concept of mnemonic interlock, results show that, instead of retrieving specific memories, depressed patients tend to produce sequences of consecutive categoric memories. This process may contribute to the maintenance of an overgeneral retrieval style.

Adult↗

PubMed1983

Forgetting and use of memory aids in 20 to 70 year olds everyday life.

In order to examine age differences in everyday memory experiences, twelve younger (mean age = 28) and twelve older (mean age = 59) adults kept diaries of their experiences of memory failures and use of memory aids. There was a general increase with age in the absolute number of memory failures, upset ratings about memory failures, and frequency of memory aid use. There were no age differences in the relative frequency of particular types of memory failures or memory aids that were used. The results suggested that older adults experience more memory failures and are more concerned about memory failures than younger adults, but that they attempt to deal with this problem by increased use of memory aids.

Adult↗