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PubMed1995

Differential age-related influences on memory for verbal-symbolic information and visual-spatial information?

Adults from a wide range of ages were administered parallel versions of three memory tasks designed to involve verbal-symbolic information or visual-spatial information. Several analytical procedures were used to determine whether there were selective age-related effects on measures reflecting spatial information processing compared to those reflecting verbal-symbolic information processing. The results provided little support for this hypothesis and instead were consistent with the existence of a common age-related factor that contributes to the age differences in many cognitive measures.

Adolescent↗
PubMed1995

Differential sensitivity of human naive and memory CD4+ T cells for dexamethasone.

Human CD45RA+ ('naive') and CD45RO+ ('memory') CD4+ T cells were compared with respect to their sensitivity to dexamethasone (DEX). In three different activation pathways, i.e. (i) immobilized anti-CD3, (ii) immobilized anti-CD3 plus soluble anti-CD28 and (iii) soluble anti-CD2 plus soluble anti-CD28, naive CD4+ T cells appeared more sensitive to DEX than memory CD4+ T cells. In the anti-CD3 system this difference in sensitivity was apparent at a suboptimal DEX concentration. Addition of anti-CD28 rendered the cells largely insensitive to DEX, indicating that the CD28 pathway is less dependent of the DEX-sensitive transcription factor AP-1. However, the alternative pathway of T cell activation through CD2/CD28 triggering was highly sensitive to DEX when naive cells were studied; in the case of memory cells, at least a 10-fold higher DEX concentration was needed to achieve a comparable inhibition. The strong inhibitory effect of DEX on naive CD4+ T cells stimulated via the alternative pathway was completely abrogated by activation of protein kinase C (PKC) with phorbol myristate acetate. Our data suggest that at least two different mechanisms contribute to DEX resistance, i.e. CD28 triggering and PKC activation, which may occur more effectively in memory cells making them less sensitive to DEX.

CD2 Antigens↗
PubMed1995

Differential effects of methylphenidate on working memory in ADHD children with and without comorbid anxiety.

OBJECTIVE: To examine the effects of methylphenidate (MPH) on working memory and behavior in anxious and nonanxious children with attention-deficit hyperactivity disorder (ADHD). METHOD: A total of 40 ADHD children (22 nonanxious, 18 anxious) completed a randomized, double-blind, placebo-controlled, crossover trial with three doses (0.3, 0.6, 0.9 mg/kg) of MPH. A serial addition task was used to assess working memory; direct observation of motor activity indexed behavior. RESULTS: MPH improved working memory in the nonanxious ADHD group but not in the comorbidity anxious group. By contrast, MPH reduced activity level in both groups. The presence of concurrent learning disabilities did not influence stimulant response. CONCLUSIONS: The presence of comorbid anxiety in children with ADHD predicts a less robust response to stimulant treatment and suggests that ADHD with anxiety may constitute a distinct and clinically meaningful subtype of ADHD.

Anxiety Disorders↗
PubMed1977

Levodopa, parkinsonism, and recent memory.

Much controversy has existed concerning behavioral changes attributed to L-dopa treatment in parkinsonian patients. Disagreement existed pertaining to the question of whether improved functioning was temporally limited. The present study proposed to research the shorter and longer range effects of L-dopa onmemory. It was hypothesized that equated nonparkinsonian individuals would perform better than parkinsonian patients on all memory measures, and that shorter range L-dopa would perform better than longer range L-dopa patients. It was also hypothesized that the greater the functional deficiency, and the greater the symptom severity, the poorer memory functioning would be. Level of dosage was hypothesized to have no differential effect on memory functioning. Three groups of 20 subjects were tested. The short term (20 parkinsonian patients on L-dopa for 22 months or less) and the long term (20 parkinsonian patients on L-dopa for 40 months or more) patients were chosen from the neurological clinic at St. Barnabas Hospital, Bronx, N.Y. Testability was assessed by the neurologis and by WAIS Vocabulary performance. The third group consisted of spouses of the patients. All groups were equated with regard to sex, age, education, and where applicable, length of illness, functional status, and symptom severity. The instruments used to measure memory consisted of the Guild Memory Test, the Memory Span for Objects, the Knox Cube, and the Tactile Memory Test. WAIS Vocabulary scaled score was used as a covariate in an analysis of covariance on each of the nine memory subtests. Statistically significant differences were obtained at the .01 level among groups on all measures. Orthogonal comparisons resulted in significant differences at the .01 level between parkinsonian patients and nonparkinsonian subjects on all measures. Short term and long term L-dopa patients differed significantly on six of the nine measures, notably those testing verbal types of memory. Significant correlations were obtained between functional deficiency and eight measures; however, symptom severity correlated with only one measure. None of the memory measures correlated significantly with level of dosage. The major conclusion was reached that all of the initial improvement shown following L-dopa initiation is not sustained permanently; the elevated level of memory functioning appears to be temporally limited.

Humans↗
PubMed2005

Beyond heritability: neurotransmitter genes differentially modulate visuospatial attention and working memory.

A cued, visuospatial attention task and a working memory task were administered to 89 healthy adults genotyped for a T-to-C polymorphism in CHRNA4, a nicotinic receptor subunit gene. Increasing gene dose of the C allele of the CHRNA4 gene (i.e., no C alleles, one C allele, two C alleles) was associated with increased reaction time (RT) benefits of valid attentional cuing and reduced RT costs of invalid cues, but was not associated with working memory performance. In a second experiment, 103 healthy persons were genotyped for a G-to-A polymorphism of the dopamine beta-hydroxylase (DBH) gene. Increasing gene dose of the G allele of the DBH gene was associated with increased working memory accuracy at a high memory load. However, there was no consistent association between the DBH gene and visuospatial attention. Thus, a double dissociation was observed, with visuospatial attention associated with CHRNA4 but not the DBH gene and, conversely, working memory associated with the DBH gene but not CHRNA4. The results show that normal allelic variations in single neurotransmitter genes modulate individual differences in processing components of cognitive functions in healthy individuals.

Adult↗
PubMedDate not supplied

Differential mechanisms of impairment of remote memory in Alzheimer's and frontotemporal dementia.

This paper describes retrograde memory performances of 12 Alzheimer's disease (AD) patients and 12 frontotemporal dementia (FTD) patients. First of all, we observed that FTD and AD patients did not differ for language tests (verbal fluency tests and oral denomination 80), for semantic memory tests, for logical memory test and Benton visual memory test and differed for anterograde verbal memory and frontal tests. Concerning retrograde memory, there was no difference between AD and FTD patients in retrograde memory scores (autobiographical memory interview, Crovitz's task, French public events interview battery) and both FTD and AD patients exhibited a retrieval deficit in their remote memory. We observed that the mechanisms of remote memory deficit was different in FTD and in AD patients. We observed no classical paradigm of Ribot for FTD patient's remote informations, and they appeared to have lost of access to memories and executive difficulties. In AD, the results indicated these patients' ability to learn new information and to search semantic memory failed.

Aged↗
PubMed1984

Delayed signal detection, differential reinforcement, and short-term memory in the pigeon.

In two discrete-trial delayed-detection experiments, six pigeons were trained on dependent concurrent variable-interval schedules. Pecking a red side key was reinforced when the brighter of two white lights (S1) had been presented on the center key, and pecking a green side key was reinforced when the duller of two white lights (S2) had been presented on the center key. Incorrect responses were red side-key pecks following S2 presentations and green side-key pecks following S1 presentations; these resulted in three-second blackouts. In Experiment 1, the time between presentation of S1 or S2 on the center key and the onset of the red and green side keys was varied nonsystematically from 0.06 seconds to 19.69 seconds across experimental conditions. Stimulus discriminability decreased as the stimulus-choice delay increased. A rectangular-hyperbolic function better described this decrease in discriminability over time than did a negative-exponential function. In Experiment 2, at each of three stimulus-choice delays (0.06, 3.85, and 10.36 seconds), relative reinforcer frequency for correct responses to the red and green side keys was varied by changing the values of the dependent concurrent variable-interval schedules. The sensitivity of choice to relative reinforcer frequency was independent of the decrease in stimulus discriminability with increasing stimulus-choice delay.

Animals↗
PubMed2005

TGF-beta 1 attenuates the acquisition and expression of effector function by tumor antigen-specific human memory CD8 T cells.

TGF-beta1 is a potent immunoregulatory cytokine. However, its impact on the generation and effector function of Ag-specific human effector memory CD8 T cells had not been evaluated. Using Ag-specific CD8 T cells derived from melanoma patients immunized with the gp100 melanoma Ag, we demonstrate that the addition of TGF-beta1 to the initial Ag activation cultures attenuated the gain of effector function by Ag-specific memory CD8 T cells while the phenotypic changes associated with activation and differentiation into effector memory were comparable to control cultures. These activated memory CD8 T cells consistently expressed lower mRNA levels for T-bet, suggesting a mechanism for TGF-beta1-mediated suppression of gain of effector function in memory T cells. Moreover, TGF-beta1 induced a modest expression of CCR7 on Ag-activated memory CD8 T cells. TGF-beta1 also suppressed cytokine secretion by Ag-specific effector memory CD8 T cells, as well as melanoma-reactive tumor-infiltrating lymphocytes and CD8 T cell clones. These results demonstrate that TGF-beta1 suppresses not only the acquisition but also expression of effector function on human memory CD8 T cells and tumor-infiltrating lymphocytes reactive against melanoma, suggesting that TGF-beta1-mediated suppression can hinder the therapeutic benefits of vaccination, as well as immunotherapy in cancer patients.

Cell Line, Tumor↗
PubMed2003

Dopamine and octopamine differentiate between aversive and appetitive olfactory memories in Drosophila.

The catecholamines play a major role in the regulation of behavior. Here we investigate, in the fly Drosophila melanogaster, the role of dopamine and octopamine (the presumed arthropod homolog of norepinephrine) during the formation of appetitive and aversive olfactory memories. We find that for the formation of both types of memories, cAMP signaling is necessary and sufficient within the same subpopulation of mushroom-body intrinsic neurons. On the other hand, memory formation can be distinguished by the requirement for different catecholamines, dopamine for aversive and octopamine for appetitive conditioning. Our results suggest that in associative conditioning, different memories are formed of the same odor under different circumstances, and that they are linked to the respective motivational systems by their specific modulatory pathways.

Animals↗
PubMed2005

Differential effects of lead exposure on components of verbal memory.

AIMS: To determine if verbal learning and memory requiring acquisition and retention of information is differentially affected by lead exposure. METHODS: The Rey Auditory Verbal Learning Test (RAVLT), a test of verbal learning and memory, was administered to 256 English speaking lead smelter workers who had a mean (SD) age of 41 (9.4) years and employment duration of 17 (8.1) years. Lead exposure variables, based on up to 25 years of prior blood lead data, included a mean (SD) current blood lead (PbB) of 28 (8.8) microg/dl, working lifetime time weighted average blood lead (TWA) of 39 (12.3) microg/dl, and working lifetime integrated blood lead index (IBL) of 728 (434.4) microg-y/dl. Associations of these chronic and recent lead exposure variables with measures from the RAVLT were modelled through multiple linear regressions after controlling for age and educational achievement. RESULTS: PbB was not associated with any of the RAVLT variables. However, TWA and IBL contributed significantly to the explanation of variance of measures of encoding/storage and retrieval but not to immediate memory span, attention, and learning. Grouping study participants by RAVLT performance according to three recognised clinical memory paradigms showed significantly higher TWA and IBL in the group with "generalised memory impairment" after adjusting for age and educational achievement. We examined recall mechanisms in each group by serial position in the word list and found stronger primacy (recall of words from the beginning of the list) in the "no impairment" and "retrieval difficulties" groups while the "generalised memory impairment" group had better performance on recency (recall of words from the end of the list). CONCLUSIONS: Lead exposure over years and not PbB interfered with the organisation and recall of previously learned verbal material. Chronic lead exposure affects encoding/storage and retrieval of verbal information.

Adult↗
PubMed2005

Differential involvement of internal clock and working memory in the production and reproduction of duration: a study on older adults.

The present study uses the inter-individual variability in time perception of a group of elderly participants to differentiate the processes underlying time production and time reproduction. Participants performed duration production and reproduction tasks. They were also administered working memory tests and a spontaneous motor tempo task. The findings suggest that duration production and duration reproduction involve different mechanisms. Correlational analyses revealed a double dissociation: production was only correlated with spontaneous motor tempo and reproduction only with working memory measures. These findings suggest that the internal clock rate modulates the production of duration and that reproduced duration varies according to working memory capacities.

Aged↗
PubMed1993

How to differentiate retrieval from storage deficit: a stochastic approach to semantic memory modeling.

Some of the methods currently used to differentiate retrieval from storage deficits in brain damaged patients are revisited. Indices based on association or agreement measures among the responses given by the subject on repeated trials, as well as direct estimates of storage and retrieval abilities based on crude percentages, are open to criticism. A simple Markov chain stochastic approach, which is free of the drawbacks of the other methods and which distinguishes storage from retrieval deficits more reliably and powerfully, is proposed.

Association Learning↗
PubMed1992

Rheumatoid synovium is enriched in CD45RBdim mature memory T cells that are potent helpers for B cell differentiation.

OBJECTIVE: To delineate the phenotype and function of synovial T cells in rheumatoid arthritis (RA). METHODS: T cells from normal subjects or from RA peripheral blood (PB), synovial fluid (SF), or synovial tissue (ST) were analyzed phenotypically and functionally. RESULTS: RA SF and ST T cells were found to be markedly enriched in CD45RAdim, CD45RO+, CD45RBdim mature memory cells, whereas in the PB, CD45RAbright naive T cells were more frequent than CD45RO+ memory T cells, and only a minority were CD45RBdim. SF and ST T cells proliferated less well and produced less interleukin-2 in response to mitogenic stimuli than did PB T cells. However, synovial T cells effectively promoted the production of Ig from normal B cells. Moreover, PB and synovial T cells differed in their capacity to down-regulate immunoglobulin production. Anti-CD3-stimulated PB T cells suppressed Ig production unless their proliferation was prevented with mitomycin C. In contrast, synovial T cells were potent helpers of B cell Ig production regardless of antecedent treatment with mitomycin C. To examine the relationship between the CD45RBdim phenotype and B cell help, CD45RBdim T cells were sorted from PB. As opposed to the findings with synovial T cells, suppression by control PB CD45RBdim T cells was observed, but only when large numbers were employed. B cell Ig production was enhanced after treatment of PB CD45RBdim T cells with mitomycin C. In contrast, healthy control sorted CD45RBbright or sorted CD4+, CD45RO+, CD45RBbright T cells did not support Ig secretion. After treatment with mitomycin C, both of these populations were more effective helpers of Ig production. CONCLUSION: RA synovium is enriched in differentiated CD45RBdim memory T cells with potent helper activity and diminished capacity to down-regulate B cells, strongly implying an active role for these cells in the production of Ig in the synovium, and thus in the propagation of disease.

Adult↗
PubMed2001

Cognitive effects of neurotoxic lesions of the nucleus basalis magnocellularis in rats: differential roles for corticopetal versus amygdalopetal projections.

The cholinergic hypothesis states that cholinergic neurons of the basal forebrain nucleus basalis magnocellularis (nbm) that project to cortical and amygdalar targets play an important role in memory. Biochemical studies have shown that these target areas are differentially sensitive to different excitotoxins (e.g., ibotenate vs. quisqualate). This observation might explain the finding from many behavioural studies of memory that different excitotoxins affect memory differentially even though they produce about the same level of depletion of cholinergic markers in the cortex and similar cortical electrophysiological effects. Thus, the magnitude of mnemonic impairment might be related to the extent of damage to cholinergic projections to the amygdala more than to the extent of damage to corticopetal cholinergic projections. This explanation might similarly apply to the observation that the immunotoxin 192 IgG-saporin produces mild effects on memory when injected into the nbm. This is because it damages cholinergic neurons projecting to the cortex but not those projecting to the amygdala. Studies comparing the effects on memory of ibotenic acid vs. quisqualic acid lesions of the nbm are reviewed as are studies of the mnemonic effects of 192 IgG-saporin. Results support the cholinergic hypothesis and suggest that amygdalopetal cholinergic neurons of the nbm play an important role in the control of memory.

Journal Article↗
PubMed2006

Recruitment of PRC1 function at the initiation of X inactivation independent of PRC2 and silencing.

In mammals X inactivation is initiated by expression of Xist RNA and involves the recruitment of Polycomb repressive complex 1 (PRC1) and 2 (PRC2), which mediate chromosome-wide ubiquitination of histone H2A and methylation of histone H3, respectively. Here, we show that PRC1 recruitment by Xist RNA is independent of gene silencing. We find that Eed is required for the recruitment of the canonical PRC1 proteins Mph1 and Mph2 by Xist. However, functional Ring1b is recruited by Xist and mediates ubiquitination of histone H2A in Eed deficient embryonic stem (ES) cells, which lack histone H3 lysine 27 tri-methylation. Xist expression early in ES cell differentiation establishes a chromosomal memory, which allows efficient H2A ubiquitination in differentiated cells and is independent of silencing and PRC2. Our data show that Xist recruits PRC1 components by both PRC2 dependent and independent modes and in the absence of PRC2 function is sufficient for the establishment of Polycomb-based memory systems in X inactivation.

Animals↗
PubMedDate not supplied

MSH/ACTH4-10: a tool to differentiate between the role of vasopressin in memory consolidation or retrieval processes.

MSH/ACTH4-10 induces a dose dependent increase of latency scores during retention of a passive avoidance response, when injected SC prior to retention but not when administered immediately after the learning trial. Intracerebroventricular administration of anti-vasopressin serum immediately after the learning trial or 1 hr prior to retention induces marked deficits in passive avoidance behavior as indicated by low latencies during retention. SC injection of MSH/ACTH4-10 increased latency scores in animals which received anti-vasopressin serum prior to retention, but did not alter latencies in animals, which received anti-vasopressin serum after the learning trial. These results suggest that MSH/ACTH4-10 is involved in retrieval processes and is able to differentiate between the effects of vasopressin on memory consolidation and on retrieval.

Adrenocorticotropic Hormone↗