Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “memory differentiation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,243 records · Page 69Linked to original sources
PubMed1995

Generation of memory B cells and plasma cells in vitro.

After germinal center B cells undergo somatic mutation and antigen selection, they become either memory B cells or plasma cells, but the signal requirements that control entry into either pathway have been unclear. When purified human germinal center cells were cultured with interleukin-2, interleukin-10, and cells expressing CD40 ligand, cells with characteristics of memory B cells were generated. Removal of CD40 ligand from the system resulted in terminal differentiation of germinal center B cells into cells with the characteristics of plasma cells. These results indicate that CD40 ligand directs the differentiation of germinal center B cells toward memory B cells rather than toward plasma cells.

ADP-ribosyl Cyclase↗
PubMed1984

Rey Auditory-Verbal Learning Test performance of patients with and without memory impairment.

Investigated performance on the Rey Auditory Verbal Learning Test (AVLT) of 92 psychiatric and neurological patients classified as memory-impaired (N = 45) or non-memory-impaired (N = 47). The groups were comparable on age and education. Relative to the non-memory-impaired Ss, performance of the memory-impaired patients was significantly lower on all AVLT scores, ps less than .01. The AVLT appears to hold promise as a quick screening measure for the clinical evaluation of patients with suspected verbal learning and memory impairments.

Diagnosis, Differential↗
PubMed2001

Differential effects of Ecstasy and cannabis on self-reports of memory ability: a web-based study.

Given the legal status of MDMA (3,4-methylenedioxymethamphetamine), or Ecstasy, face-to-face access to participants is sometimes difficult. The number of participants in studies of cognitive performance amongst Ecstasy users is variable, with the average being around 30. Access to a larger number of participants is clearly desirable. The present investigation accessed a larger sample size using a web-based design. A website was developed and used for data collection. Prospective memory ability was assessed using the Prospective Memory Questionnaire. Self-report of day-to-day memory performance was investigated using the Everyday Memory Questionnaire. The Drug Questionnaire assessed the use of other substances as well as Ecstasy, allowing a regression design to isolate the contribution of each substance to any variance on the cognitive measures. Preliminary findings (N = 488) indicate that there is a clear double dissociation between the impact of Ecstasy and cannabis. We found that cannabis was associated with reports of 'here-and-now' cognitive problems in short-term and internally cued prospective memory. In contrast, Ecstasy was associated with reports of long-term memory problems, which were more related to storage and retrieval difficulties. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1987

Selectivity of pirenzepine in the central nervous system. II. Differential effects of pirenzepine and scopolamine on performance of a representational memory task.

The behavioral effects of the two muscarinic antagonists scopolamine and pirenzepine were examined using a representational memory task for rats in a T-maze. Rats were pretrained to a criterion of 100% correct responses for daily sessions of 10 paired-run trials. The training procedures eliminated all neophobic or wary responses, and response times were invariably short (less than 3 s). Following the initial training sessions, guide cannulae were surgically implanted bilaterally over the hippocampus of each animal. Following recovery from surgery, animals were injected with saline (0.5 microliter to each hippocampus), scopolamine hydrobromide (0.5 microliter of a 60 mg/ml solution (30 micrograms) to each side), or pirenzepine (0.5 microliter of a 69.1 mg/ml solution (34.6 micrograms) to each side) according to a fixed schedule. Saline injections aimed between the blades of the dorsal dentate gyrus failed to produce any change in the performance of the memory task. Initial doses of scopolamine, applied to the same area, produced a decrease in the percentage of correct responses as did the initial dose of pirenzepine. In contrast to pirenzepine, scopolamine also produced increases in response times even to the point of defaulted trials (response times greater than 90 s) in some animals following drug injections. Saline injections failed to produce significant impairments on the days following scopolamine injections, although animals receiving pirenzepine injections were still impaired on the two days immediately following the initial pirenzepine injection. Subsequent doses of pirenzepine were ineffective in producing an impairment of performance while scopolamine injections were less effective than the initial dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Differential effects of the antimuscarinic agents darifenacin and oxybutynin ER on memory in older subjects.

OBJECTIVES: To investigate the effects of darifenacin controlled-release (CR) and oxybutynin extended-release (ER) on cognitive function (particularly memory) in older subjects. METHODS: Healthy subjects (n=150) >/=60 years were randomised to darifenacin, oxybutynin ER or placebo in a multicentre, double-blind, double-dummy, parallel-group, 3-week study. Doses were administered according to US labels: oxybutynin ER 10mg once daily (od), increasing to 15mg od then 20mg od by week 3; darifenacin 7.5mg od in weeks 1 and 2, then 15mg od in week 3. The primary end point was accuracy on the Name-Face Association Test (delayed recall) at week 3. RESULTS: Results of the Name-Face Association Test at week 3 showed no significant difference between darifenacin and placebo on delayed recall (mean difference, -0.06, p=0.908). In contrast, oxybutynin ER resulted in memory impairment, with significantly lower scores than placebo and darifenacin (mean differences, -1.30, p=0.011 and -1.24, p=0.022, respectively) for delayed recall on the Name-Face Association Test at week 3. Additional tests of delayed recall indicated significant memory impairment with oxybutynin ER versus placebo at certain time points, whereas darifenacin was similar to placebo. No between-treatment differences were detected in self-rated memory, demonstrating that subjects were unaware of memory deterioration. CONCLUSIONS: While darifenacin had no significant effects on memory versus placebo, oxybutynin ER caused significant memory deterioration (magnitude of effect comparable to brain aging of 10 years). The results also demonstrate that subjects may not recognise/report memory deterioration.

Aged↗
PubMed1999

The differential roles of right and left sides of the brain in memory formation.

A series of transitions in chick memory formation, with sharp standard timings, which were revealed by amnestic agents, coincide with a series of brief windows of enhanced recall ('retrieval events'), repeating with periods of 16 min (left hemisphere) and 25 min (right). Their timings were recently confirmed by: (1) the demonstration of a brief dip in recall 5 min after each left hemisphere event in the period 0-100 min, (2) spontaneous use of the eye providing direct input to the hemisphere undergoing an event, and (3) good performance in a delayed match-to-sample task after 100 min, only at times of near, or exact coincidence (400 min) with right and left events. The exact coincidence is accompanied by a late episode of consolidation, as is a transition in memory formation in the zebra finch with precisely the same timing. Linkages between right and left versions of a single experience appear to be established as a result of near coincidences of events. The greater involvement of the left hemisphere in initiating such interactions appears to be responsible for a wide range of asymmetries described for interocular transfer and unilateral insult.

Animals↗
PubMed2003

Differential involvement of nucleus accumbens shell and core subregions in maternal memory in postpartum female rats.

Maternal memory refers to the long-term retention of maternal responsiveness as a consequence of animals' prior experiences with their young. This study examined the relative roles of 2 subregions of the nucleus accumbens (NA; shell and core) in maternal memory in rats. NA shell lesions either before or immediately after a short experience significantly disrupted maternal memory, but lesions after a 24-hr maternal experience had no effect. NA core lesions had no significant impact on maternal memory. Cycloheximide (a protein synthesis inhibitor) at a high dose (25 micrograms/microliter) infused in the NA shell immediately after 1 hr of maternal experience also significantly disrupted maternal memory, whereas infusions in the medial preoptic area had no effect. It was concluded that the NA shell, but not the NA core, is involved in the consolidation of maternal memory.

Animals↗
PubMed2002

Differential contribution of NMDA receptors in hippocampal subregions to spatial working memory.

N-methyl-D-aspartate (NMDA) receptor-dependent synaptic plasticity in the mammalian hippocampus is essential for learning and memory. Although computational models and anatomical studies have emphasized functional differences among hippocampal subregions, subregional specificity of NMDA receptor function is largely unknown. Here we present evidence that NMDA receptors in CA3 are required in a situation in which spatial representation needs to be reorganized, whereas the NMDA receptors in CA1 and/or the dentate gyrus are more involved in acquiring memory that needs to be retrieved after a delay period exceeding a short-term range. Our data, with data from CA1-specific knockout mice, suggest the possibility of heterogeneous mnemonic function of NMDA receptors in different subregions of the hippocampus.

Animals↗
PubMed2003

Differentiating simple versus complex processing speed: influence on new learning and memory performance.

The current study was designed to examine how the construct of human information processing speed is conceptualized and measured, while also examining the influence of information processing speed on higher cognitive processes (i.e., learning). A mixed medical sample of 92 subjects participated in this study. Subjects underwent a broad-based neuropsychological evaluation, including measures of verbal and visuospatial new learning, spatial and verbal working memory, simple reaction time, choice reaction time, and information processing speed. Principal components factor analysis with varimax rotation resulted in a three-factor solution, comprised of: (1) simple speed/reaction time, (2) complex information processing and new learning, and (3) working memory. Notably, this factor solution identified 2 distinct forms of processing speed--simple and complex information processing speeds. In contrast to the abundance of literature grouping these two constructs together under one term (i.e., processing speed), these results indicate simple and complex speed to be distinct constructs assessed with different neuropsychological instruments. While the expected relationship between complex information processing capacities and working memory abilities was evident in this study, information processing speed also showed a significant relationship with new learning ability. The implications of this intriguing relationship are discussed.

Adult↗
PubMed2001

Differential effects of glucose on modulation of emotional and nonemotional spatial memory tasks.

Research examining the memory-enhancing effects of glucose in humans has been limited to mnemonic tasks lacking affective components, even though glucose may be a mechanism for emotion-induced memory enhancement. This limitation does not permit analysis of interactions between the enhancing properties of emotional stimuli and glucose. Participants were administered either glucose or saccharin 15 min prior to completing a neutral or emotional spatial memory task. Performance under three glycemic conditions (100 mg/kg or 50 g glucose, or placebo) for the two sets of emotional stimuli revealed a significant interaction. Both 100-mg/kg and 50-g doses of glucose resulted in impaired performance for emotional stimuli. For neutral stimuli, a 100-mg/kg dose enhanced memory, whereas a 50-g dose showed no effect. Results indicate that the enhancing effects of emotional stimuli may be attenuated by the consumption of glucose and suggest that recent food consumption should be considered in paradigms examining memory.

Adult↗
PubMed2004

Parsing the recognition memory components of the WMS-III face memory subtest: normative data and clinical findings in dementia groups.

The WMS-III face memory subtest was developed as a quick, reliable, measure of non-verbal recognition memory. While the face memory subtest has demonstrated clinical sensitivity, the test has been criticized for low correlation with other WMS-III visual memory subtests and for failing to differentiate performance between clinical groups. One possible reason for these findings may be due to the impact of response bias associated with recognition memory tests. Four studies were conducted to evaluate the utility of applying signal detection measures to the face memory subtests. The first two studies used the WMS-III standardization data set to determine age and education effects and to present normative and reliability data for hits, false positives, discriminability and response bias. The third study tested the hypothesis that using response components and signal detection measures would enhance the correlation between face memory and the other WMS-III visual memory subtests. The fourth study compared performance of patients with Alzheimer's disease, Huntington's disease, Korsakoff's syndrome and demographically matched controls on the new face memory scores. The new measures did not have higher correlation with other WMS-III visual memory measures than the standard scoring of the test. Analysis of the clinical samples indicated that the discriminability index best differentiated patients from controls. The response components, particularly delayed false positives, differentiated performance among the clinical groups. Normative and reliability data are presented.

Adolescent↗
PubMed1989

Young and older adults' appraisal of memory failures in young and older adult target persons.

A person-perception approach was employed to investigate people's appraisal of young or older target persons' everyday memory failures as described in 28 vignettes of more serious and less serious types of memory failure. In Experiment 1 of the study, 115 young adults rated each of 28 memory failure vignettes on a 7-point seriousness scale. Mrs. X, the target person in the vignettes, was described either as age 30 or 70. Vignettes in the more serious category were rated, as expected, more stringently than vignettes in the less serious category. Also, the young subjects rated Mrs. X age 70 more stringently than Mrs. X age 30, regardless of the seriousness level of the vignettes. In Experiment 2, 79 older adults evaluated the same vignettes, again with Mrs. X either age 30 or 70. Again, vignettes in the more serious category were rated more stringently than vignettes in the less serious category. However, older adults rated Mrs. X age 30 and Mrs. X age 70 equivalently. In a final overall analysis, older adults were more lenient than the young in memory failure judgments, and their differential leniency was most apparent in judgments of the serious vignettes.

Adolescent↗
PubMed1998

Memory and language in neurodegenerative diseases.

This article reviews recent studies concerning memory and language disorders in Alzheimer's disease and other neurodegenerative conditions. It shows how different memory and language subcomponents may differentially be impaired in different neurodegenerative diseases and at different stages of the same disease.

Alzheimer Disease↗
PubMed2003

Phenotypic and functional analysis of T cells homing into the CSF of subjects with inflammatory diseases of the CNS.

The recruitment of lymphocytes across the blood brain barrier (BBB) is mediated by adhesion molecules and chemokines. The expression of activation markers and of chemokine receptors on T cells homing to the nervous system (NS) may help define their functional state. In the cerebrospinal fluid (CSF) of subjects with inflammatory neurological diseases (IND), including multiple sclerosis, we observed an increased number of T cells coexpressing CXCR3 and CCR5 as well as T cells with a CD45RO+ CCR7+ CD27+ memory phenotype. A subset of CCR7+ T cells coexpressed CXCR3 and CCR5. We also detected an increased number of interferon-gamma-producing T cells in the CSF compared with peripheral blood, mostly but not exclusively in the CD45RO+ CCR7- CD27- compartment. T helper 1 (Th1) clones, established from the CSF of individuals with IND and from a healthy subject, similarly migrated to CXCL10, CXCL12, and CCL5. CXCL10, CXCL12, and CCL19 were increased in the CSF of individuals with neuroinflammation. These findings suggest that CSF is enriched in Th1-polarized memory T cells capable of differentiating into effector cells upon antigen encounter. These cells are recruited into the CSF by inducible chemokines. Thus, CSF represents a transitional station for T cells trafficking to and from the NS.

Adult↗
PubMed1999

Spatial memory deficits in patients with lesions affecting the medial temporal neocortex.

Lesion studies in monkeys suggest that neocortical subregions of the medial temporal lobe (MTL) carry memory functions independent of the hippocampal formation. The present study investigates possible differential contributions of MTL subregions to spatial memory in humans. Eye movements toward remembered spatial cues (memory-guided saccades) with unpredictably varied memorization delays of up to 30 seconds were recorded in patients with postsurgical lesions of the right MTL, either restricted to the hippocampal formation (n = 3) or including the adjacent neocortex (n = 5) and in 10 controls. Although saccadic targeting errors of patients with selective hippocampal lesions did not differ from controls, saccadic targeting errors of patients with additional neocortical involvement showed a significant and contralaterally pronounced increase at memorization delays above 20 seconds. We conclude that the human medial temporal neocortex carries spatial memory functions independent of the hippocampal formation and distinct from spatial short-term memory.

Adult↗
PubMed2003

Neuropsychological correlates of hippocampal and rhinal cortex volumes in patients with mesial temporal sclerosis.

Considerable progress has been made toward understanding the function of the primate rhinal cortex, comprising the entorhinal (ErC) and perirhinal (PrC) cortices. However, translating animal models to human memory has been limited by the technological problems associated with characterizing neural structures in vivo. Functional correlates of hippocampal and rhinal cortex volume changes were examined in a sample of 61 temporal lobe epilepsy patients with mesial temporal sclerosis (MTS; 33 left, 28 right). Patients were administered the Wechsler Adult Intelligence Scale (revised or third edition), the Wechsler Memory Scale (revised or third edition), and a spatial maze task. Neuropsychological data, together with rhinal cortex and hippocampal volumes, collected in our earlier study (O'Brien CE, Bowden SC, Whelan G, Cook MJ, unpublished observations), were analyzed using multiple regression. The only significant predictor of verbal memory function was the difference score between the volume of left hippocampus and the left PrC. Spatial maze scores were predicted by the bilateral sum of ErC volume. The difference score between the left hippocampus and left PrC volumes was the most powerful predictor of verbal episodic memory. Right hippocampal volume was not a significant predictor of nonverbal episodic memory. Verbal and nonverbal semantic memory were not significantly predicted by any combination of rhinal cortex structures. This quantitative study suggests a lateralized or material-specific memory function for the left hippocampus and left PrC, in contrast to the bilateral role of the ErC. The left hippocampus and left PrC appear to act on verbal memory function through an opposing relationship. Finally, differentiation between hippocampal and subhippocampal components in terms of episodic and semantic memory, respectively, could not be supported by the current data.

Adult↗
PubMed1993

Vivid memory for 'everyday' pains.

A 2-part study in which memory for everyday pains was investigated is reported. The first part compared ratings of vivid, 'flashbulb' memories of pain and non-pain events. Memories of pain events were rated as having been more surprising, having induced more negative emotional change, and having provoked greater change in ongoing activity than their non-pain event counterparts. In the second part of the study the relationship between remembering the pain event, experiencing the pain and re-experiencing the sensory qualities was examined. No subject reported sensory re-experiencing and 41% of subjects were unable to recall the sensory quality of the pain experience memory. Elements of pain experience (recalled intensity, distress and sensory quality) were differentially associated with components of pain event memory. Distress was associated with the reported frequency with which the pain event was rehearsed and with ratings of emotional and activity change induced by the pain event. In contrast, ratings of the intensity and sensory quality of the pain were associated with the reported vividness of the pain event memory. It is concluded that memories of painful events are readily retrievable and that the memory for a pain event, the sensory and affective qualities of pain experience and somatosensory component of pain are separated in their encoding and/or retrieval. The possible mechanisms whereby pain memories are encoded and retrieved are discussed. The clinical implications of the data concerning how judgements of past pain are made and the possible role of memory in coping are also noted.

Adolescent↗
PubMed1999

CD4+ CD45RA+ and CD4+ CD45RO+ T cells differ in their TCR-associated signaling responses.

Peripheral CD4+ T cells can be divided into two different functional populations based on the expression of distinct isoforms of the surface molecule CD45. We have investigated the differences in the proximal signaling induced by anti-CD3 monoclonal antibody in purified populations of "naive" CD45RA+ and "memory" CD45RO+ human CD4+ T cells. Expression of cell surface CD3, CD4 and CD28 was comparable between RA+ and RO+ cells. However, TCR-directed stimulation in the form of anti-CD3 produced markedly different patterns of intracellular signaling. Greater inositol triphosphate generation occurred in naive cells and the rise in intracellular free calcium was also substantially greater in naive than in memory cells. Cells with the naive phenotype were considerably more active in TCR-dependent tyrosine phosphorylation, both at an overall level and specifically in terms of TCR-zeta and ZAP-70 phosphorylation. Despite these differences in phosphorylation, the amounts of TCR-zeta, ZAP-70 and Ick were equivalent between the two subsets. These findings suggest that the TCR-dependent signaling is differentially regulated in naive and memory CD4+ T cells. This may be due to differences in the way that the two isoforms of the CD45 phosphatase regulate the activity of proximal kinases in the TCR signaling pathway, and could be an important means by which the unique functions of differentiated T cell populations are maintained.

Animals↗