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PubMed2000

Extent, pattern, and correlates of remote memory impairment in Alzheimer's disease and Parkinson's disease.

Content and contextual memory for remote public figures and events was assessed with a modified version of the Presidents Test in patients with Alzheimer's disease (AD) or Parkinson's disease (PD). Contributions of executive functioning, semantic memory, and explicit anterograde memory to remote memory abilities were also examined. The AD group had temporally extensive deficits in content and contextual remote memory not accountable for by dementia severity. The PD group did not differ from the control group in remote memory, despite anterograde memory impairment. These results support the position that different component processes characterize remote memory, various mnemonic and nonmnemonic cognitive processes contribute to remote memory performance, and anterograde and remote memory processes are dissociable and differentially disrupted by neurodegenerative disease.

Aged↗
PubMed2001

A sex difference on a novel spatial working memory task in humans.

Neurophysiological and behavioral evidence suggests that the prefrontal cortex (PFC) may be sexually differentiated in nonhuman primates. The present study examined whether there are sex differences in working memory in humans that might reflect sexual differentiation of human PFC. Male and female undergraduates were administered a novel multitrial spatial working memory task (SPWM) and a verbal working memory task. In three experiments, females committed significantly fewer working memory errors and took significantly less time to reach criterion than males on the SPWM task. The female advantage was not accounted for by differences in general intellectual ability, attention, perceptual speed, incidental memory, or speed of verbal access. In Study 3, a sex difference was also observed on a measure of verbal working memory. The findings suggest that some prefrontal functions may be sexually differentiated in humans.

Adult↗
PubMed2000

The effects of electroconvulsive therapy on memory of autobiographical and public events.

BACKGROUND: Retrograde amnesia is the most persistent cognitive adverse effect of electroconvulsive therapy (ECT); however, it is not known whether ECT has differential effects on autobiographical vs impersonal memories. This study examined the short- and long-term effects of differing forms of ECT on memory of personal and impersonal (public) events. METHODS: Fifty-five patients with major depression were randomly assigned to right unilateral (RUL) or bilateral (BL) ECT, each at either low or high electrical dosage. The Personal and Impersonal Memory Test was administered by blinded raters at baseline, during the week after ECT, and at the 2-month follow-up. Normal controls were tested at matched intervals. RESULTS: Shortly after ECT, patients recalled fewer events and event details than controls, with the deficits most marked for impersonal compared with personal events. Bilateral ECT caused more marked amnesia for events and details than RUL ECT, and especially for impersonal memories. These effects were independent of electrical dosage and clinical outcome. At the 2-month follow-up, patients had reduced retrograde amnesia, but continued to show deficits in recalling the occurrence of impersonal events and the details of recent impersonal events. CONCLUSIONS: The amnestic effects of ECT are greatest and most persistent for knowledge about the world (impersonal memory,) compared with knowledge about the self (personal memory), for recent compared with distinctly remote events, and for less salient events. Bilateral ECT produces more profound amnestic effects than RUL ECT, particularly for memory of impersonal events.

Amnesia↗
PubMed1988

Human memory T cell activation. Effects of monoclonal antibodies directed at interleukin-2, receptors for interleukin-2, or interferon-gamma.

Several polyclonal T cell activators can induce the differentiation of quiescent antigen-specific memory T cells (memory cells) into specific secondary cytotoxic T cells, in the absence of the original priming alloantigens. Such activation represents a potential pathway by which immunologically nonspecific signals can elicit specific antiallograft immunity. We therefore investigated the molecular basis for antigen-independent activation of memory cells using as probes recombinant interleukin-2 and monoclonal antibodies directed at IL-2, IL-2 receptors (IL-2R), or interferon-gamma (IFN-gamma). Antigen-specific memory cells, generated in human long-term-primary mixed lymphocyte cultures, were induced to proliferate, exhibit antigen specific secondary cytolytic activity, or produce IFN-gamma by recombinant DNA human IL-2 produced in E Coli. Monoclonal antibodies directed at the IL-2R or at IL-2 inhibited IL-2-mediated proliferation, cytolytic activity, or production of IFN-gamma. Monoclonal antibodies directed at IFN-gamma did not inhibit alloantigen or IL-2 mediated activation of memory cells. Our findings suggest that successful interaction between IL-2 and its receptor expressed on memory cells represents a plausible pathway by which an immunologically nonspecific signal might elicit specific antiallograft immunity. Moreover, therapeutic strategies that include antibodies directed at the IL-2 and/or IL-2R and not antibodies directed at IFN-gamma will inhibit IL-2-dependent alloimmunity.

Antibodies, Monoclonal↗
PubMed1996

[Evaluation of memory in neuropsychological clinic].

Following an introduction in which the history of the clinical evaluation of memory is briefly reviewed, a methodology is described for the evaluation of patients complaining of memory loss, or in whom such deterioration is observed, although it was not the reason for consultation. The main instruments currently available for evaluation are described. Methodological problems posed by the use of these instruments, and the precautions necessary when interpreting the data thus obtained, are discussed. The conclusion summarizes the use of the proposed methodology, both in the differential diagnosis of changes of memory and in establishing individual rehabilitation programmes or compensation.

Alzheimer Disease↗
PubMed2003

A role for Toll-like receptors in acquired immunity: up-regulation of TLR9 by BCR triggering in naive B cells and constitutive expression in memory B cells.

Toll-like receptors (TLRs) are pattern recognition receptors that trigger innate immunity. In this study we investigated the expression of 10 TLRs in human naive and memory B-cell subsets. We report that in human naive B cells most TLRs are expressed at low to undetectable levels, but the expression of TLR9 and TLR10 is rapidly induced following B-cell-receptor (BCR) triggering. In contrast, memory B cells express several TLRs at constitutively high levels. The differential expression of TLR9 correlates with responsiveness to its agonist, CpG DNA. Thus, human memory B cells proliferate and differentiate to immunoglobulin (Ig)-secreting cells in response to CpG, while naive B do so only if simultaneously triggered through the BCR. The BCR-induced expression of TLRs in human naive B cells prevents polyclonal activation in a primary response, because it restricts stimulation to antigen-specific B cells. In contrast, the constitutive expression of TLRs in memory B cells allows polyclonal activation of the entire memory pool. Thus, in human B cells TLRs are downstream of BCR and play a role both in the primary response and in the memory phase.

B-Lymphocyte Subsets↗
PubMed1996

Generation effect in short-term verbal and visuospatial memory: comparisons between dementia of Alzheimer type and dementia of frontal lobe type.

Memory deficit is the predominant presenting symptom in dementia. To compare short-term memory (STM) deficit in early dementia of Alzheimer type (DAT) vs frontal lobe type (DFT), and determine the residual memory capacity for stimulation, the generation effect (the memory advantage of items generated rather than read) was tested on verbal and visuospatial STM in patients with DAT (n = 10), DFT (n = 9) and in age-matched normal controls (n = 12). The generation effect enhanced performance in all groups. However, the profile of STM deficit differed in the two dementias: verbal and visuospatial memory were both decreased in DAT vs verbal memory only in DFT. These results provide a further criterion for differentiating between DAT and DFT, and show that memory performance can be enhanced in early dementia using techniques such as the generation effect.

Aged↗
PubMed2002

[Validity of the Japanese version of Rivermead Behavioural Memory Test for evaluation of everyday memory function in patients with mild Alzheimer's disease].

OBJECTIVE: To validate the Japanese version of Rivermead Behavioural Memory Test (RBMT) in evaluating everyday memory function in patients with mild Alzheimer's disease (AD). SUBJECTS AND METHODS: Subjects were 100 patients with probable AD of very mild or mild stages of dementia as measured by the Clinical Dementia Rating (CDR). Scores of the Japanese version of RBMT were correlated with scores of the Alzheimer's Disease Assessment Scale-Cognitive part (ADAS-J Cog) and of the Wechsler Memory Scale-Revised (WMS-R). The everyday disability caused by the impairment of memory function was also assessed with the Memory Checklist (CL), and was correlated with the RBMT scores. In addition, the diagnostic value of the RBMT was examined in 46 pairs of AD patients and healthy subjects; the patients were chosen from the present subjects and the healthy subjects from the participants in the previous RBMT standardization study as one-by-one matched for age, sex, and educational level. RESULTS: Both of the total screening score and profile score of RBMT were significantly correlated with all of the weighted sum scores of verbal, visual, general, and delayed memory tests of the WMS-R and the word recall subtest score of the ADAS-J Cog. Both of the RBMT scores were also highly correlated with the CL score and the memory subscale of the CDR. In the analysis of the diagnostic accuracy, both of the RBMT scores correctly classified 98% of AD patients and 96% of normal volunteers by setting the cut-off scores of 6/5 for the total screening score and of 14/13 for the total profile score. CONCLUSIONS: The RBMT is a useful tool in evaluating everyday memory function in patients with mild AD. This test also accurately differentiates AD patients from healthy individuals.

Aged↗
PubMed1999

Immediate memory, attention and communication disturbances in schizophrenia patients and their relatives.

BACKGROUND: Schizophrenia has been defined in part by disturbances of thought and language. The non-schizophrenic relatives of patients also have been found to show subtle disturbances of language that may be associated with vulnerability. Investigators have hypothesized that these phenomena in patients and their relatives are, at least in part, the result of weaknesses in facets of attention and memory. METHODS: The present study assessed some neuropsychological process correlates of three different measures of thought and language symptoms in 55 stable out-patients, using tests of immediate auditory memory impairment and auditory distractability, and carefully controlling for generalized deficit effects. A parallel assessment was made of referential communication disturbances in 59 non-schizophrenic relatives of patients and 24 control subjects matched to the relatives. RESULTS: In patients, formal thought disorder, disorganization, and referential communication disturbances were all associated with each other and with auditory distractability. In addition, as expected, referential communication disturbances were associated with immediate auditory memory impairment. Referential disturbance ratings for relatives were similar in magnitude to those for the stable out-patients, and much higher than for controls. However, the relatives' language ratings were not associated specifically with weaknesses in attention or memory as measured. CONCLUSIONS: Impairments in immediate auditory memory and attention are associated differentially with different types of communication disturbances in schizophrenia patients. The cognitive substrate for referential communication disturbances in relatives appears to differ qualitatively from that for patients.

Adult↗
PubMed2001

Differential interaction of platelet-activating factor and NMDA receptor function in hippocampal and dorsal striatal memory processes.

The interaction between platelet activating factor (PAF) and NMDA receptor function in hippocampal and dorsal striatal memory processes was examined. In both a hidden and a visible platform water maze task, peripheral post-training injection of MK-801 (0.05 mg/kg) impaired memory. Post-training intrahippocampal infusions of PAF (1.0 microg/0.5 microl) enhanced memory in the hidden platform task, while intradorsal striatal infusion of PAF (1.0 microg/0.5 microl) enhanced memory in the visible platform task. The memory impairing effects of post-training injection of MK-801 was blocked by concurrent intrahippocampal infusion of PAF. In contrast, post-training injection of MK-801 blocked the memory enhancing effects of concurrent intradorsal striatal infusion of PAF. The results suggest that (1) the memory enhancing effects of intracerebral PAF infusion involve an interaction with NMDA receptor function, and (2) the nature of this interaction may represent a differential mechanism mediating the distinct roles of the hippocampus and dorsal striatum in cognitive memory and stimulus-response habit formation, respectively.

Animals↗
PubMedDate not supplied

Dissociation of the effects of neuropeptide Y on feeding and memory: evidence for pre- and postsynaptic mediation.

In mice not deprived of food, centrally administered neuropeptide Y (NPY) increases feeding and improves retention. In this study, we examined the effect of C-terminal NPY fragments on feeding and on memory retention. Mice were trained to avoid footshock in a T-maze. After training NPY, NPY fragments (20-36 and 26-36) or saline were administered intracerebroventricularly. Food consumption was measured during the first hour after training and memory retention was measured one week after training. NPY elicited a 544% increase in feeding compared to the saline control. Neither NPY fragment significantly increased feeding. Both NPY and NPY(20-36) improved retention compared to the saline-treated group. NPY(26-36) did not improve retention. NPY administered to well-trained mice results in amnesia. As a further test of the differential effect of NPY on memory processing and eating, we determined in well-trained mice whether administration of NPY and NPY(20-36) resulted in amnesia. Both NPY and NPY(20-36) resulted in amnesia, but only NPY stimulated feeding. These results are compatible with NPY effects on feeding being mediated through postsynaptic (Y1)NPY receptors and effects on memory retention being mediated through presynaptic (Y2)NPY receptors.

Animals↗
PubMed1995

Differential time courses of c-fos mRNA expression in hippocampal subfields following acquisition and recall testing in mice.

Spatio-temporal patterns of c-fos mRNA expression were studied in the mouse brain following the partial acquisition of an appetitive conditioning task in a Skinner box. We used two experimental situations: during the initial acquisition of the task (acquisition paradigm) and during the retention test (recall paradigm). In both paradigms the in situ hybridization signal was exclusively located in the hippocampal formation and the posterior cingulate cortex. However, the time-dependent pattern of expression was quite different according to the experimental situation: mRNA levels peaked at 90 min post-test in both paradigms but returned to basal (control) level by 180 min in the acquisition group, while in CA3 and DG subfields, high levels of mRNA expression were maintained at 180 min in the recall group. Taken together these results suggest that the IEG c-fos is implicated in the different phases of post-acquisition memory processes and involve a differential spatio-temporal regulation of its expression in hippocampal subfields.

Animals↗
PubMed2005

Physiological dissociation in hippocampal subregions in response to amygdala stimulation.

Previous studies indicated that the amygdala, when activated by emotional or electrical stimulation, modulates hippocampal-dependent memory processes and synaptic plasticity. Although the modulatory effect of the amygdala has often been generalized to the hippocampal formation, studies suggest that hippocampal subregions may display distinct functional profiles and may respond distinctively to amygdala activation. In this study we assessed the effect of basolateral amygdala (BLA) stimulation on long-term potentiation (LTP)--a synaptic model of memory--induced by a standard (sdTS) or a strong theta stimulation (sgTS) in the hippocampal dentate gyrus (DG) and CA1, in anesthetized rats. The modulatory stimulation was applied 30 s before or after the tetanus stimulation. Results show that while BLA activation impaired CA1 LTP induced with an sdTS, it enhanced LTP in the DG under both sdTS and sgTS conditions. These findings provide evidence for a differential amygdalar control of hippocampal memory subsystems, and may contribute to the understanding of the complexity of memory processes under stressful conditions.

Amygdala↗
PubMed1994

Hemispheric encoding/retrieval asymmetry in episodic memory: positron emission tomography findings.

Data are reviewed from positron emission tomography studies of encoding and retrieval processes in episodic memory. These data suggest a hemispheric encoding/retrieval asymmetry model of prefrontal involvement in encoding and retrieval of episodic memory. According to this model, the left and right prefrontal lobes are part of an extensive neuronal network that subserves episodic remembering, but the two prefrontal hemispheres play different roles. Left prefrontal cortical regions are differentially more involved in retrieval of information from semantic memory and in simultaneously encoding novel aspects of the retrieved information into episodic memory. Right prefrontal cortical regions, on the other hand, are differentially more involved in episodic memory retrieval.

Brain↗
PubMed2005

Understanding the generation and function of memory T cell subsets.

Memory T cells can be broadly divided into central memory and effector memory subsets, which are endowed with different capacities to home to lymphoid or non-lymphoid tissues, to proliferate in response to antigen or cytokines and to perform effector functions. In the past few years progress has been made in understanding the properties of these memory T cell subsets and, in particular, the signals required for their generation and maintenance. Collectively these data point to a critical role of central memory T cells in conferring long-term immunity.

Cell Differentiation↗
PubMed1999

The electrophysiology of incidental and intentional retrieval: ERP old/new effects in lexical decision and recognition memory.

Event-related brain potentials (ERPs), recorded from a 128-sensor array were used to differentiate brain processes associated with intentional vs incidental memory retrieval. Two experiments examined ERP differences between old (studied) and new (non-studied) words and pseudowords while subjects performed either a recognition memory task or lexical decision task. Previous research has related a P600 old/new effect to the recollection of details, and the present experiments show that this effect was not amplified by intentional retrieval. The P600 effect was larger for words than pseudowords. An earlier (300 to 500 ms), frontally maximal, N400-like old/new effect ('FN400') was similar for words and pseudowords. A third, previously unidentified, mid-frontal, old/new effect was associated with only pseudoword recognition from 300 to 500 ms. Results are discussed with respect to dual-process theories of recognition memory.

Adult↗
PubMed2003

Low frequency of plasma nerve-growth factor detection is associated with death of memory B lymphocytes in HIV-1 infection.

Nerve growth factor (NGF) regulates B cell activation and differentiation and is an autocrine survival factor for memory B lymphocytes. We have reported recently that the number of memory B cells is reduced during HIV-1 infection. In this study we evaluated whether alteration in the NGF supply was involved in memory B cell loss in HIV-1-infected subjects. High rate of cell death in vitro was observed in memory B cells from HIV-1-infected individuals compared to uninfected donors (26.2 +/- 2.5%versus 7.9 +/- 1.4%, P < 0.001). The increased expression of Fas on memory B cells from infected subjects did not enhance the susceptibility of the cells to Fas-mediated apoptosis in vitro. The frequency of NGF detection in plasma from HIV-1-infected subjects was significantly lower than in healthy donors (33.6%versus 63.6%, P < 0.001). Also, the median plasma NGF in HIV-1-infected individuals was significantly lower than in uninfected controls (5 versus 14 pg/ml, respectively, P < 0.01). Interestingly, the plasma NGF level was correlated directly 1 to the percentage of memory B cells (P < 0.05). HIV-1-infected subjects with a low number of peripheral memory B cells had a reduced incidence of plasmatic NGF (7.4%) compared to patients with a normal level of memory B cells (37%, P < 0.01). Moreover, the addition of recombinant NGF (1 micro g/ml) to cultures of purified B cells reduced cell death of memory B cells from HIV-1-infected subjects from 24.04 +/- 3.0% to 17.4 +/- 1.3% (P < 0.01). HIV-1-infected individuals also carried higher levels of natural anti-NGF autoantibodies compared to uninfected subjects. In conclusion, we found that memory B cells from HIV-1-infected individuals are primed for cell death. Our study suggests an association between low frequency of plasma NGF detection and the increased cell death of memory B lymphocytes observed during HIV-1 infection. Low levels of NGF in plasma may be due to reduced supply or to NGF binding to natural anti-NGF autoantibodies.

Autoantibodies↗
PubMed1991

Lateralized brain damage and performance on trail making A and B, Digit Span Forward and Backward, and TPT Memory and Location.

The present retrospective study was undertaken to determine whether Trail Making Test A and B, Digit Span Forward and Backward, and TPT Memory and Location scores are differentially sensitive to right or left hemisphere brain damage. Groups of patients with right, left, and generalized cerebral lesions and matched normal controls were compared. Results showed a relative failure for any individual measure, difference, or ratio score to reliably distinguish between right and left hemisphere lesions. Patients with diffuse lesions performed significantly worse than non-neurologic medical controls and right and left lesion groups on Trails A and TPT Memory and Location. Results are discussed in terms of specific methodological variables including chronicity of lesion, the nature of the task demands, and priming effects.

Journal Article↗