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 217 records · Page 12Linked to original sources

PubMed1993

The development of short-term memory span: separable effects of speech rate and long-term memory.

We report an experiment investigating the mechanisms responsible for short-term memory span and its development by examining the relationship between memory span and speech rate for words and nonwords of differing spoken lengths. Linear functions related memory span to speech rate for both words and nonwords in children of different ages. The functions for nonwords had equivalent slopes (interpreted as reflecting a contribution from a speech-based process) but lower intercepts (interpreted as reflecting a contribution from a long-term memory component) than the functions for words. Children in both age groups studied showed evidence of a relationship between speech rate and memory span and part of the difference in memory span between age groups appears to reflect a difference in speech rate. However, there is also evidence that the long-term memory component of memory span shows greater efficiency in older children.

Age Factors↗

PubMed2006

The cannabinoid receptor agonist WIN 55,212-2 facilitates the extinction of contextual fear memory and spatial memory in rats.

RATIONALE: Previous studies demonstrated that pharmacological blockade of CB1 cannabinoid receptors decreases the extinction of conditioned fear and spatial memory in rodents. However, the effects of CB1 cannabinoid receptor activation in this response remain unclear. OBJECTIVES: To evaluate the effects of the cannabinoid agonist WIN 55,212-2 (WIN) and the cannabinoid antagonist SR 147778 (SR) on the extinction of contextual fear memory in rats 24 h or 30 days after fear conditioning. METHODS: For fear conditioning, rats were placed in the conditioning chamber for 3 min and received a 1-s electric foot shock (1.5 mA). Retrieval testing consisted of a 3-min exposure to the conditioning chamber and extinction training consisted of successive 9-min exposures at 24-h intervals. Rats were also evaluated in the open field and water maze reversal task. RESULTS: The administration of SR (1.0 mg/kg, i.p.) and WIN (0.25 mg/kg, i.p.) before extinction training disrupted and facilitated, respectively, the extinction of 24 h contextual fear memory. These effects were not related to any disturbance in memory retrieval, unconditioned freezing expression, or locomotor activity. WIN (0.25 mg/kg, i.p.) also facilitated the extinction of 30-day-old contextual fear memory, while the prior administration of SR (0.2 mg/kg, i.p.) antagonized this response. The facilitative effect of WIN on memory extinction does not seem to be specific for contextual fear memory because it was also observed in the water maze reversal task. CONCLUSIONS: These results suggest cannabinoid receptor agonists as potential drugs to treat anxiety disorders related to the retrieval of aversive memories.

Animals↗

PubMed1992

Intrahippocampal injections of benzodiazepine and muscimol impair working memory but not reference memory of rats in the three-panel runway task.

In a three-panel runway task, the benzodiazepine chlordiazepoxide at 3.2 and 10 mg/kg i.p. significantly increased the number of errors (attempts to pass through two incorrect panels of the three panel-gates at four choice points) in a test of working memory, but it had no effect on errors in a test of reference memory. This effect of 10 mg/kg chlordiazepoxide on working memory was blocked by the benzodiazepine receptor antagonist flumazenil at 10 mg/kg. Intrahippocampal injection of chlordiazepoxide at 10 and 32 micrograms/side significantly increased the number of working memory errors. This effect of intrahippocampal chlordiazepoxide (32 micrograms/side) was attenuated not only by flumazenil at 10 mg/kg but also by the gamma-aminobutyric acid (GABA)A receptor antagonist bicuculline at 3.2 mg/kg. Intrahippocampal injection of the GABAA receptor agonist muscimol at 100 and 320 ng/side also significantly increased working memory errors. Neither chlordiazepoxide nor muscimol affected the number of reference memory errors when injected into the hippocampus at doses up to 32 micrograms/side or 320 ng/side, respectively. These results suggest that activation of the GABAA/benzodiazepine receptor complex in the hippocampus impairs working memory, but does not affect reference memory.

Animals↗

PubMed2006

Visual-spatial learning and memory in schizotypal personality disorder: continued evidence for the importance of working memory in the schizophrenia spectrum.

Verbal episodic memory deficits, a well-established feature of the schizophrenia spectrum, have also been found in individuals with schizotypal personality disorder (SPD), although visual-spatial episodic memory has proven harder to examine. To address this, we administered the Visual Object Learning Test (VOLT), a measure of visual-spatial learning and memory, as well as the California Verbal Learning Test (CVLT) and a verbal working memory test, to 50 individuals with SPD, 19 with other personality disorders (OPD), and 17 healthy volunteers. Compared to both other groups, individuals with SPD learned verbal and visual-spatial information at a reduced rate and recalled fewer words and objects after a long delay. Verbal working memory performance eliminated diagnostic differences in these episodic memory domains. These findings suggest that it is possible to detect both auditory and visual processing episodic memory abnormalities in the spectrum and that these deficits are uniformly a function of verbal working memory impairments.

Adult↗

PubMed2006

Memories affect mood: evidence from covert experimental assignment to positive, neutral, and negative memory recall.

Memory recall has been proposed as a common and effective mood regulation strategy. Although several studies have presented results suggesting that recalling valenced memories affects subsequent mood, their designs allow for alternative interpretations of the observed effects. Two such alternatives include the reverse effect (mood effects on memory due to non-experimental assignment to memory recall condition) and demand characteristics of the experiment. We used covert experimental assignment to memory condition, asking subjects (N=314; 56% female) to recall memories that were primarily positive, neutral, or negative. Results showed the expected effect on mood (p<.002), with reported mood worst in the negative memory condition, better in the neutral condition, and best in the positive condition. These results suggest that valenced memory recall does indeed exert an effect on mood, and may do so even without the individual's awareness.

Adaptation, Psychological↗

PubMed2006

Phencyclidine affects memory in a nitric oxide-dependent manner: working and reference memory.

Phencyclidine (PCP), a non-competitive NMDA receptor antagonist, was used to model schizophrenia-like cognitive dysfunctions of learning and memory in rats using the Morris water maze model for spatial memory. A protocol introduced by Baldi and co-workers was used to distinguish working memory from reference memory. Male Sprague-Dawley rats were administered PCP (2.0 mg/kg) before the first swimming trial on each of five spatial memory acquisition days, either alone or after pre-treatment with the nitric oxide synthase inhibitor, L-NAME (10 mg/kg). Probe tests for memory were conducted before and after each acquisition session. The results showed that PCP disrupted the acquisition of both working and reference memory. Pre-treatment with L-NAME reversed both these effects of PCP. L-NAME treatment by itself did not significantly alter either acquisition or retention of spatial memory.

Analysis of Variance↗

PubMed2006

Memory reconsolidation: sensitivity of spatial memory to inhibition of protein synthesis in dorsal hippocampus during encoding and retrieval.

Reconsolidation is a putative neuronal process in which the retrieval of a previously consolidated memory returns it to a labile state that is once again subject to stabilization. This study explored the idea that reconsolidation occurs in spatial memory when animals retrieve memory under circumstances in which new memory encoding is likely to occur. Control studies confirmed that intrahippocampal infusions of anisomycin inhibited protein synthesis locally and that the spatial training protocols we used are subject to overnight protein synthesis-dependent consolidation. We then compared the impact of anisomycin in two conditions: when memory retrieval occurred in a reference memory task after performance had reached asymptote over several days; and after a comparable extent of training of a delayed matching-to-place task in which new memory encoding was required each day. Sensitivity to intrahippocampal anisomycin was observed only in the protocol involving new memory encoding at the time of retrieval.

Animals↗

PubMed2005

The effect of two types of memory training on subjective and objective memory performance in healthy individuals aged 55 years and older: a randomized controlled trial.

The objective of the study was to examine the effectiveness of two types of memory training (collective and individual), compared to control (waiting list), on memory performance. Participants were 139 community-dwelling older individuals recruited through media advertisements asking for people with subjective memory complaints to participate in a study. Data were collected at baseline, and at 1 week and 4 months after the intervention. Training efficacy was assessed using measures of subjective and objective memory performance. After the intervention, participants in the collective training group reported more stability in memory functioning and had fewer feelings of anxiety and stress about memory functioning. In addition, positive effects were found on objective memory functioning. Compared with the other two groups, the collective training group participants had an improved recall of a previously learned word list. Compared to controls, participants in the individual training group reported fewer feelings of anxiety and stress in relation to memory functioning.

Affect↗

PubMed2001

Facilitative effects of an adenosine A1/A2 receptor blockade on spatial memory performance of rats: selective enhancement of reference memory retention during the light period.

The present experiment was designed to examine the role of adenosine in spatial working and reference memory in rats using an 8-arm radial maze task which requires the integrity of the hippocampal formation. We investigated the effects of the unselective adenosine A1/A2 receptor antagonist theophylline on acquisition and retention of spatial working and reference memory. As there is evidence that brain extracellular adenosine levels vary significantly during the light-dark cycle, we tested the effects of theophylline both during the light and the dark period. Acquisition of the task was investigated for 10 consecutive days after rats received daily injections of vehicle or theophylline (15 mg/kg, intraperitoneally). Retention was tested in two nondrug sessions 7 and 14 days after completion of acquisition. The results demonstrate that in saline-treated control rats acquisition and retention of reference memory and, to a lesser extent, working memory was superior in the dark period. The results further revealed that daily administration of theophylline interacted with days to selectively enhance reference memory acquisition in the light, but not in the dark, period. In addition, reference memory retention was significantly enhanced in those rats who learned the task under theophylline treatment during the light period. Overall, the results show that in saline-treated control rats the effectiveness of acquisition and retention of spatial information in a radial maze strongly depends on the time of day. The higher levels of maze performance in the dark period might be related to a better functioning of involved brain systems in the active period of the rat. Furthermore, theophylline-induced blockade of adenosine A1/A2 receptors in the light, but not in the dark, period selectively enhanced reference memory acquisition and retention. Variations of brain extracellular adenosine levels during the light-dark cycle might account for the restriction of reference memory enhancing effects of theophylline to the light period.

Animals↗

PubMed2004

Memory for faces dissociates from memory for location following anterior temporal lobectomy.

It has been suggested that the right and left mesial temporal lobes are specialized for processing different types of information for long-term memory (LTM). Although findings have been consistent in regard to the dominant role of the left mesial temporal lobe (MTL) in verbal memory, the role of the right MTL in non-verbal memory remains debatable. Given the existence of two cortical pathways specialized for processing different types of visuospatial information, we examined whether memory processing for these two types of information might also be differentially localized. The effect of unilateral anterior temporal lobectomy (ATL) was compared for memory for unfamiliar faces and a novel sequence of spatial locations in 86 ATL patients (left ATL (LATL) = 35; right ATL (RATL) = 51) pre- and post-surgery to examine the contributions of right and left MTL structures to LTM for pattern and spatial information. Memory for spatial location was not related to side of ATL or time of testing. On the facial memory task, RATL patients showed impairments relative to LATL patients prior to surgery, which became magnified after surgery. These results extend the proposed dissociation between an occipitotemporal and an occipitoparietal pathway for processing visuospatial information by demonstrating dissociations in LTM systems for these two types of information. Lesions in the right MTL, adjacent to the cortical structures believed to be specialized for facial recognition, specifically impair the memory encoding of new faces, but not spatial locations.

Adult↗

PubMed2001

Integrated brain activity in medial temporal and prefrontal areas predicts subsequent memory performance: human declarative memory formation at the system level.

After an era in which lesion studies have identified the declarative memory system and its essential anatomical structures, functional imaging and event-related potential studies have begun to delineate the neural underpinnings of declarative memory formation at the system level. By memory formation, we refer to those mnemonic processes present during encoding that transform perceptual representations into enduring memories. Recent studies have revealed that distinct regions in medial temporal and prefrontal areas exhibit more neural activity during successful than unsuccessful memory formation. We attempt to identify the nature of the processes underlying these subsequent memory effects. Reviewed data suggest specific mnemonic operations in the medial temporal lobe that may be integrated with semantic/perceptual operations and subserving operations in the prefrontal cortex. The formation of relational and non-relational memories may be supported by distinct subregions within these two brain regions. While the medial temporal lobe may have a serial organizational structure, with a processing hierarchy, interactions between medial temporal and prefrontal areas seem to occur in a parallel and bi-directional fashion. Interacting with this system, emotionally arousing events enhance neural activity in the amygdala, which in turn may modulate processing in other brain regions responsible for declarative memory formation.

Animals↗

PubMed1998

Human working memory capacity is 7+/-2 in a radial maze with distracting interruption: possible implication for neural mechanisms of declarative and implicit long-term memory.

Human participants were instructed to walk out along each of the arms of a 15-m in diameter, 8-arm radial maze once and only once. In order to approximate the circumstances under which laboratory rats remember visited sites, our human participants were asked to select arms in an unsystematic order. They scored an average of 7.6 to 7.8 correct choices, even if midway during a trial there was a 5-min interruption filled with a verbal-spatial interfering task (a scavenger hunt) or a 15-min interruption filled with a visuospatial task (a maze-running computer simulation). This finding extends our earlier research with humans in 13- or 17-arm radial mazes under nondelay conditions, in which we also found working memory (WM) capacity for about 7 to 9 places, the same as that of laboratory rats. We discuss earlier findings in other laboratories, showing that rats can successfully bridge long radial maze task interruptions of 5 or 8 h, and we compare our results also to those from studies in which human participants were not discouraged from reducing memory load by responding systematically in radial mazes. Because the radial maze task takes minutes to complete even under nondelay conditions its routine consideration as a working memory task in the animal literature alters the assumptions often made about the duration of WM in the human literature. Accumulating empirical findings about place-memory in humans, nonhuman mammals, and birds suggest it might be productive to reevaluate this theoretical issue with respect to present knowledge about the roles of the hippocampus and other brain structures in declarative memory and in procedural or implicit memory, while considering the hypothesis that some forms of information may exploit long-term memory in parallel with working memory.

Adolescent↗

PubMed2003

Working memory retention systems: a state of activated long-term memory.

High temporal resolution event-related brain potential and electroencephalographic coherence studies of the neural substrate of short-term storage in working memory indicate that the sustained coactivation of both prefrontal cortex and the posterior cortical systems that participate in the initial perception and comprehension of the retained information are involved in its storage. These studies further show that short-term storage mechanisms involve an increase in neural synchrony between prefrontal cortex and posterior cortex and the enhanced activation of long-term memory representations of material held in short-term memory. This activation begins during the encoding/comprehension phase and evidently is prolonged into the retention phase by attentional drive from prefrontal cortex control systems. A parsimonious interpretation of these findings is that the long-term memory systems associated with the posterior cortical processors provide the necessary representational basis for working memory, with the property of short-term memory decay being primarily due to the posterior system. In this view, there is no reason to posit specialized neural systems whose functions are limited to those of short-term storage buffers. Prefrontal cortex provides the attentional pointer system for maintaining activation in the appropriate posterior processing systems. Short-term memory capacity and phenomena such as displacement of information in short-term memory are determined by limitations on the number of pointers that can be sustained by the prefrontal control systems.

Animals↗

PubMed1998

Reward-produced memories regulate memory-discrimination learning, extinction, and other forms of discrimination learning.

In memory-discrimination learning, reward-produced memories are differentially rewarded such that they are the only stimuli available to support discriminative responding. Memory-discrimination learning was used in this study as follows: Reward-produced memories that were assumed to regulate instrumental performance in previously reported extinction and discrimination learning investigations were isolated and explicitly differentially reinforced (prior to a shift to extinction) in each of 4 runway investigations with rats. Results obtained here in the explicit discrimination learning stage and in the subsequent extinction stage were consistent with the prediction of the memory view and with prior discrimination learning and extinction findings. The memory interpretation was applied to memory-discrimination learning, to extinction, and to 2 other types of discrimination learning. It appears that a theory must use reward-produced memories to explain all 4 types of discrimination learning.

Animals↗

PubMed1997

B cell memory in xid mice is long-lived despite reduced memory B cell frequency.

Brutons tyrosine kinase (Btk) deficient xid mice have a diminished primary T cell dependent immune response, resulting in a reduced memory B cell frequency. Boosting at 35 days post primary immunization, however, generates a normal secondary immune response, indicating a functional memory B cell compartment. The longevity of B cell memory appears to depend on both the presence of antigen and expression of cell survival genes such as bcl-2. Since there is a natural decay in the number of memory B cells over time and since xid B cells have been demonstrated to have reduced Bcl-2 levels, we aimed at determining whether B cell memory of xid mice would be long-lasting. This report demonstrates that memory B cell precursors are detectable in xid mice more than 100 days after primary immunization. Furthermore, a secondary immune response of normal magnitude and kinetics can be generated in xid mice at 150 days after primary immunization indicating that B cell memory is long-lived in xid mice. Thus, although survival of B cell memory is presumably dependent on immunoglobulin (Ig)-mediated interaction with antigen, this interaction does not depend solely on signalling through Btk.

Animals↗

PubMed2000

Protective long-term antibody memory by antigen-driven and T help-dependent differentiation of long-lived memory B cells to short-lived plasma cells independent of secondary lymphoid organs.

Memory is a hallmark of immunity. Memory carried by antibodies is largely responsible for protection against reinfection with most known acutely lethal infectious agents and is the basis for most clinically successful vaccines. However, the nature of long-term B cell and antibody memory is still unclear. B cell memory was studied here after infection of mice with the rabies-like cytopathic vesicular stomatitis virus, the noncytopathic lymphocytic choriomeningitis virus (Armstrong and WE), and after immunization with various inert viral antigens inducing naive B cells to differentiate either to plasma cells or memory B cells in germinal centers of secondary lymphoid organs. The results show that in contrast to very low background levels against internal viral antigens, no significant neutralizing antibody memory was observed in the absence of antigen and suggest that memory B cells (i) are long-lived in the absence of antigen, nondividing, and relatively resistant to irradiation, and (ii) must be stimulated by antigen to differentiate to short-lived antibody-secreting plasma cells, a process that is also efficient in the bone marrow and always depends on radiosensitive, specific T help. Therefore, for vaccines to induce long-term protective antibody titers, they need to repeatedly provide, or continuously maintain, antigen in minimal quantities over a prolonged time period in secondary lymphoid organs or the bone marrow for sufficient numbers of long-lived memory B cells to mature to short-lived plasma cells.

Animals↗

PubMed1996

Memory systems in the brain and localization of a memory.

It is now clear that there are a number of different forms or aspects of learning and memory that involve different brain systems. Broadly, memory phenomena have been categorized as explicit or implicit. Thus, explicit memories for experience involve the hippocampus-medial temporal lobe system and implicit basic associative learning and memory involves the cerebellum, amygdala, and other systems. Under normal conditions, however, many of these brain-memory systems are engaged to some degree in learning situations. But each of these brain systems is learning something different about the situation. The cerebellum is necessary for classical conditioning of discrete behavioral responses (eyeblink, limb flexion) under all conditions; however, in the "trace" procedure where a period of no stimuli intervenes between the conditioned stimulus and the unconditioned stimulus the hippocampus plays a critical role. Trace conditioning appears to provide a simple model of explicit memory where analysis of brain substrates is feasible. Analysis of the role of the cerebellum in basic delay conditioning (stimuli overlap) indicates that the memories are formed and stored in the cerebellum. The phenomenon of cerebellar long-term depression is considered as a putative mechanism of memory storage.

Animals↗

PubMed1997

Protection against immunopathological consequences of a viral infection by activated but not resting cytotoxic T cells: T cell memory without "memory T cells"?

Immunological memory is a key characteristic of specific immune responses. Persistence of increased levels of precursor T cells is antigen-independent and is often used as an indicator of T cell memory. This study documents that, depending on the chosen readout, cytotoxic T lymphocyte (CTL) memory against lymphocytic choriomeningitis virus (LCMV) appears long- or short-lived in the absence of persisting antigen. To study T cell memory in the absence of persisting antigen, either short-lived antigens were used for immunization or adoptive transfer methods were used to eliminate possibly persisting antigen. These experiments revealed that increased specific precursor frequencies and CTL-mediated protection against an i.v. infection with LCMV were long-lived. In contrast, CTL-mediated protection against a peripheral infection of the skin with LCMV, or of the ovary with recombinant vaccinia virus, was short-lived. These results show that maintenance of increased specific CTL precursor frequencies and central T cell memory in lymphoid tissue (where preexisting neutralizing antibodies usually provide protection anyway) is long-lived and antigen-independent. In contrast, in protection against peripheral viral infections, where the relative kinetics of virus growth and virus elimination by T cells are of key importance, T cell memory is short-lived in the absence of antigen. This indicates that peripheral T cell memory in antibody-inaccessible tissues is mediated by antigen-activated effector T cells and apparently not by specialized memory T cells.

Adoptive Transfer↗