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PubMed1998

Memory span, naming speed, and memory strategies in poor and normal readers.

Eleven-year-old severely impaired poor readers failed to show a word length effect with pictorial presentation, but showed an effect of equal magnitude to that of reading age and chronological age controls with auditory presentation. The lack of a pictorial word length effect was unlikely to be due to slow speed of naming skills, as in one study these were at least as fast as those of the reading age controls. It is possible that the poor readers failed to verbally encode the pictures. However, they reported using verbal rehearsal, and lip movements were often observed during presentation, suggesting that they did verbally encode the items. Therefore they may have failed to show a word length effect because they did not retrieve information from the phonological store at recall. Although the poor readers had impaired naming speed skills for their age on both discrete item identification and articulation rate tasks, they could not be equated with their chronological age controls on memory span or reading when these naming speed differences were controlled. However, the groups were matched on the naming speed measures when differences in reading ability were controlled.

Child↗

PubMedDate not supplied

Dynamic cortical networks of verbal and spatial working memory: effects of memory load and task practice.

Working memory (WM), the ability to briefly retain and manipulate information in mind, is central to intelligent behavior. Here we take advantage of the high temporal resolution of electrophysiological measures to obtain a millisecond timescale view of the activity induced in distributed cortical networks by tasks that impose significant WM demands. We examined how these networks are affected by the type and amount of information to be remembered, and by the amount of task practice. Evoked potentials (EPs) were obtained from eight subjects performing spatial and verbal versions of a visual n-back WM task (n = 1, 2, 3) on each of three testing days. In well-trained subjects, WM tasks elicited transient responses reflecting different subcomponents of task processing, including transient (lasting 0.02-0.3 s) task-sensitive and load-sensitive EPs, as well as sustained responses (lasting 1-1.5 s), including the prestimulus Contingent Negative Variation (CNV), and post-stimulus frontal and parietal Slow Waves. The transient responses, with the exception of the P300, differed between the verbal and spatial task versions, and between trials with different response requirements. The P300 and the Slow Waves were not affected by task version but were affected by increased WM load. These results suggest that WM emerges from the formation of a dynamic cortical network linking task-specific processes with non-specific, capacity-limited, higher-order attentional processes. Practice effects on the EPs suggested that practice led to the development of a more effective cognitive strategy for dealing with lower-order aspects of task processing, but did not diminish demands made on higher order processes. Thus a simple WM task is shown to be composed of numerous elementary subsecond neural processes whose characteristics vary with type and amount of information being remembered, and amount of practice.

Adult↗

PubMed1977

Memory for lists of sounds by the bottle-nosed dolphin: convergence of memory processes with humans?

After listening to a list of as many as six discriminably different 2-second sounds, a bottle-nosed dolphin classified a subsequent probe sound as either "old" (from the list) or "new." The probability of recognizing an old probe was close to 1.0 if it matched the most recent sound in the list and decreased sigmoidally for successively earlier list sounds. Memory span was estimated to be at least four sounds. Overall probabilities of correctly classifying old and new probes corresponded closely, as if recognition decisions were made according to an optimum maximum likelihood criterion. The data bore many similarities to data obtained from humans tested on probe recognition tasks.

Animals↗

PubMed2004

Severe chronic graft-versus-host disease is characterized by a preponderance of CD4(+) effector memory cells relative to central memory cells.

Donor alloreactive CD4(+) T cells are important to the pathogenesis of chronic graft-versus-host disease (cGVHD), but specific subsets of CD4(+) T cells responsible for GVHD have not been defined. We hypothesized that cGVHD might be associated with a preponderance of CD4(+) effector memory cells (CCR7(-)/CD62L(low), CD4(EM)). We analyzed CCR7 and CD62L expression on CD4(+) T cells from stem cell transplantation patients, who did or did not develop cGVHD, and healthy donors. Patients with cGVHD had a higher percentage of CD4(EM) cells (35.5% +/- 2.9%) than healthy donors (13.8% +/- 0.7%; P <.0001) or patients without cGVHD that received a transplant (21.7% +/- 2.1%; P <.01). Using corticosteroid dose as a surrogate marker for cGVHD severity, severe cGVHD was associated with a higher percentage of CD4(EM) cells. The proportion of CD4(EM) cells in corticosteroid-dependent patients with systemic lupus erythematosis or Wegener granulomatosis did not differ from patients without cGVHD that received a transplant. This finding implies that overrepresentation of CD4(EM) cells is a unique feature of cGVHD.

CD4-Positive T-Lymphocytes↗

PubMed1991

[A simple multiple maze test to estimate learning and memory in mice: application to the effect of scopolamine on learning and memory].

The apparatus consists of a home cage, a maze cage and a starting box. A maze with four right-middle-left decisions was placed in the maze cage. The starting box was attached and a water tap was placed at an area corresponding to the entrance of the maze. The exit of the maze and the home cage are connected with a tunnel. Food was placed in the home cage. 1) Mice were housed for 10 hr a day in the apparatus and then removed to another cage for fasting. One trial a day was carried out after fasting for more than 12 hr. In each trial, a mouse was put at the starting box, and then the number of errors (entering a blind alley) and the time until the mouse reached the home cage were counted. The mouse passed through the maze with a small number of errors and time. 2) Administration of scopolamine (0.125-0.5 mg/kg, i.p.) to a mouse that had mastered the maze transiently disturbed the maze performance dose-dependently. 3) Mice were housed for 4 hr a day. Scopolamine (0.25 mg/kg, i.p.) was administered either before or after the housing. Scopolamine disturbed the maze performance in the case of both procedures. These results suggest that the method is useful for estimating the memory in mice.

Animals↗

PubMed2005

Hippocampus-dependent memory formation: do memory type-specific mechanisms exist?

Long-term memory (LTM) formation requires gene transcription and de novo protein synthesis. The transcription factor CREB is required for hippocampus-dependent LTM formation, and it is activated by several signaling pathways, including protein kinase A (PKA), the mitogen activated protein/extracellular signal-regulated kinases (MAPK or ERKs), and Ca(2+)/calmodulin kinases (CaMKs). However, it is unknown whether all types of hippocampus-dependent LTM use the same signaling to activate transcription, and whether the transcriptional output is the same. Here we present molecular genetic and behavioral studies to demonstrate that two types of hippocampus-dependent LTM formation, spatial and contextual, require different signaling molecules. This can be illustrated by the CaMK kinases, CaMKKalpha, and CaMKKbeta, which have converse roles. CaMKKalpha is required for contextual and CaMKKbeta is required for spatial LTM formation. This leads to the surprising conclusion that there are distinct types of hippocampus-dependent LTM, which differ in their underlying molecular mechanisms.

Brain-Derived Neurotrophic Factor↗

PubMed2005

Mice deficient in OX40 and CD30 signals lack memory antibody responses because of deficient CD4 T cell memory.

Recently, we reported that a CD4(+)CD3(-)CD11c(-) accessory cell provided OX40-dependent survival signals to follicular T cells. These accessory cells express both OX40 ligand and CD30 ligand, and the receptors, OX40 and CD30, are both expressed on Th2-primed CD4 T cells. OX40 and CD30 signals share common signaling pathways, suggesting that CD30 signals might substantially compensate in OX40-deficient mice. In this report we have dissected the signaling roles of CD30 alone and in combination with OX40. CD30-deficient mice showed an impaired capacity to sustain follicular germinal center responses, and recall memory Ab responses were substantially reduced. Deficiencies in OX40 and CD30 signals were additive; secondary Ab responses were ablated in double-deficient mice. Although the initial proliferation of OX40/CD30 double-knockout OTII transgenic T cells was comparable to that of their normal counterparts, they failed to survive in vivo, and this was associated with reduced T cell numbers associated with CD4(+)CD3(-) cells in B follicles. Finally, we show that OX40/CD30 double-knockout OTII transgenic T cells fail to survive compared with normal T cells when cocultured with CD4(+)CD3(-) cells in vitro.

Animals↗

PubMed2001

Parallel memory retrieval in dual-task situations: II. Episodic memory.

Three experiments asked whether subjects could retrieve information from a 2nd stimulus while they retrieved information from a 1st stimulus. Subjects performed recognition judgments on each of 2 words that followed each other by 0, 250, and 1,000 ms (Experiment 1) or 0 and 300 ms (Experiments 2 and 3). In each experiment, reaction time to both stimuli was faster when the 2 stimuli were both targets (on the study list) or both lures (not on the study list) than when 1 was a target and the other was a lure. Each experiment found priming from the 2nd stimulus to the 1st when both stimuli were targets. Reaction time to the 1st stimulus was faster when the 2 targets came from the same memory structure at study (columns in Experiment 1; pairs in Experiment 2; sentences in Experiment 3) than when they came from different structures. This priming is inconsistent with discrete serial retrieval and consistent with parallel retrieval.

Adult↗

PubMedDate not supplied

[Time, memory, institution. Analysis of past experiences which emerge at times of crisis as a memory tract in the staff of a nursing home for the aged].

The paper analyses the feelings of the staff of an old people's home. Following an identification crisis, the group faced a massive regression. An attempt was made to solve this problem by dividing the staff into teams, each of which was entrusted with a group of old people for whose needs they would be entirely responsible. After two years, the staff were faced with problems which had previously seemed resolved. Old people in poor health were not respected as individuals. They were called by name and treated with familiarity; they were kept in bed to prevent them falling, and had to perform all their bodily functions in bed. Rebellious attitudes and depressive states were underestimated and ascribed to arteriosclerosis. An attempt was made to understand the reasons behind this regression. Small discussion groups were formed in order to reestablish the group's memory track which reorganisation and change had caused.

Homes for the Aged↗

PubMed2000

The development of working memory: further note on the comparability of two models of working memory.

This paper is a set of reflections on Kemps, De Rammelaere, and Desmet's article (2000, this issue), in which the two models by Baddeley and Pascual-Leone are compared. First, some of the similarities and differences between the two models which we identified in a 1994 paper (de Ribaupierre & Bailleux, 1994) are briefly summarized and reexamined in the light of more recent work. Second, we debate the issue of whether each model makes a specific contribution to the explanation of some of Kemps et al.'s results, that is, of whether they can be considered to be complementary. Third, we argue for the necessity of theoretical task analyses, in view of the divergent results obtained in the two tasks used (the Corsi and the Peanut tasks), notably different developmental profiles, and an overall higher level of performance in the Corsi task. Finally, we briefly summarize a very similar study in which we also used Mr. Peanut with concurrent tasks in children and in young adults and in which we obtained rather different results. By comparing the experimental procedures used in the two studies, we contribute some exploratory hypotheses, while raising issues that can easily be generalized to other visuo-spatial working memory tasks.

Adult↗

PubMed2003

Misinformation effects in eyewitness memory: the presence and absence of memory impairment as a function of warning and misinformation accessibility.

The authors report 5 experiments investigating how exposure to misleading postevent information affects people's ability to remember details from a witnessed event. In each experiment the authors tested memory using the modified opposition test, which was designed to isolate retrieval-blocking effects. The findings indicate that retrieval blocking occurs regardless of whether the misleading information is presented before or after the witnessed event. In addition, when people are warned immediately about the presence of misleading information, they can counteract retrieval-blocking effects but only if the misinformation is relatively low in accessibility. The authors discuss the findings in terms of the retrieval-blocking hypothesis and a hypothetical suppression mechanism that can counteract retrieval-blocking effects in some circumstances.

Attention↗

PubMed2003

Spatial memory for food hidden by rats (Rattus norvegicus) on the radial maze: studies of memory for where, what, and when.

Rats (Rattus norvegicus) were allowed to hide food items on an 8-arm radial maze by carrying the items from the center to boxes at the end of each arm. Retrieval tests given after rats had hidden 4 items showed that they selectively returned to the maze arms where food had been hidden (Experiments 1 and 2). When rats were allowed to hide pieces of cheese (refed food) and pretzels (less preferred food) on different arms, they both hid and retrieved cheese before pretzels (Experiments 2-5). In Experiment 6, rats chose between arms where cheese and pretzels were hidden,with cheese degraded at one delay interval but not the other. Together, these experiments indicate memory for what and where but not when.

Animals↗

PubMed1992

The representation of objects and their attributes in memory: evidence concerning memory for location.

The general principle is advanced that different attributes of objects (e.g. shape and colour) are more readily associated when they are attributes of the same object than when they are attributes of different objects. Previous studies provide support for the principle, for they have shown that a shape is more readily associated with its own colour than, for example, with the colour of its background. In the present experiments, the principle was applied to the attributes of shape and location. In four experiments it was shown that a shape was more readily associated with its own location than with the location of another object. Differences in contiguity between the presentation of the shape and the location with which the shape was to be associated were controlled for, as were other factors. The results were interpreted as providing support for the general principle stated above. It was suggested that the general principle could be explained by supposing that memory is propositional in format.

Adult↗

PubMed2003

Device modeling of ferroelectric memory field-effect transistor for the application of ferroelectric random access memory.

An improved theoretical analysis on the electrical characteristics of ferroelectric memory field-effect transistor (FeMFET) is given. First, we propose a new analytical expression for the polarization versus electric field (P-E) for the ferroelectric material. It is determined by one parameter and explicitly includes both the saturated and nonsaturated hysteresis loops. Using this expression, we then examine the operational properties for two practical devices such as the metal-ferroelectric-insulator-semiconductor field-effect transistor (MFIS-FET) and metal-ferroelectric-metal-insulator-semiconductor field-effect transistor (MFMIS-FET) as well. A double integral also has been used, in order to include the possible effects due to the nonuniform field and charge distribution along the channel of the device, to calculate the drain current of FeMFET. By using the relevant material parameters close to the (Bi, La)4Ti3O12 (BLT) system, accurate analyses on the capacitors and FeMFET's at various applied biases are made. We also address the issues of depolarization field and retention time about such a device.

Journal Article↗

PubMed1975

Nature of "memory" in T-cell mediated antibacterial immunity: cellular parameters that distinguish between the active immune response and a state of "memory".

Immunizing infection in mice with Listeria monocytogenes resulted in the generation of two distinct states of immunological reactivity. There was generated (i) a short-lived state of active immunity that functioned to urgently eliminate the infection organism from the tissues and (ii) a long-lives state of increased immunological potential that enabled the host to respond to seconday infection in an accelerated manner. Short-lived active immunity was mediated by replicating T cells and expressed by activated macrophages, and it ended when these cell types disappeared from the tissue soon after complete elimination of the parasite. Long-lived immunological protential was associated with a persistent level of delayed sensitivity and with the presence of a small number of nonreplicating protective T cells. It is suggested that the state of delayed sensitivity represents a state of immunological T-cell memory of the cell-mediated type.

Animals↗

PubMed1996

Topographic amnesia: spatial memory disorder, perceptual dysfunction, or category specific semantic memory impairment?

A 60 year old patient, SE, who presented with a severe difficulty in finding his way around previously familiar environments and a mild prosopagnosia is described. SE had herpes simplex encephalitis resulting in selective right temporal lobe damage. He showed normal spatial learning, but was severely imparied in his ability to recognise pictures of buildings and landmarks. The disorder was not confined to the visual modality, but rather involved a loss of knowledge about famous buildings and landmarks when tested from their spoken name. SE was contrasted with a more severely prosopagnosic patient, PHD, who showed normal ability to recognise buildings and landmarks, indicating that recognition of people dissociates from recognition of buildings/landmarks. It is concluded that SE's failure of place knowledge represents a category specific supramodal semantic memory impairment.

Agnosia↗

PubMed2005

Subjective memory complaints with and without objective memory impairment: relationship with risk factors for dementia.

OBJECTIVE: The authors investigated the frequency distribution of well-established risk factors for dementia--high plasma homocysteine and the apolipoprotein E epsilon4 allele (APOE epsilon4)--among older women with subjective memory complaints (SMC) but no cognitive impairment, and with mild cognitive impairment (MCI). METHODS: This was a cross-sectional, community-based study. RESULTS: Women with MCI had higher total plasma homocysteine than healthy-comparison subjects. There was also a nonsignificant excess of APOE epsilon4 carriers in the MCI than in the healthy group. Participants with SMC had higher depression and anxiety scores than healthy-comparison subjects, but did not differ from subjects in the healthy-comparison group in relation to their total plasma homocysteine and APOE epsilon4 distribution. CONCLUSIONS: MCI seems to be more closely related to well-established risk factors for dementia than is SMC.

Aged↗

PubMed1991

Memory psychophysics for areas: distortion in natural memory of a school campus.

As the perceived magnitude of a stimulus is related by power function t o the physical magnitude, the remembered visual areas and length are also related by power function to the actual areas and length. The main purpose of this study is to examine whether the power law is also applicable to remembered areas in natural environment, e.g., a school campus, and to its old memory. 31 junior high students and seven university undergraduates who graduated from the same junior high school seven years before were asked to draw a layout of the school campus. The areas of the school facilities and field, and other features of drawings such as the number of recalled facilities and objects, and direction of the sketch were assessed. Analysis showed that the areas remembered by the junior high subjects followed the power law while those remembered by the undergraduates did not. The divergence of exponents observed for undergraduates was accounted for by reconstruction by schema.

Adolescent↗