Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “learning and memory”

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

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

At least 19 recordsLinked to original sources
PubMed1989

[Memory, learning and glutamate receptor].

After a brief tetanic stimulation of an excitatory pathway in the hippocampus, synaptic transmission through the tetanized pathway is facilitated for a long period. This phenomenon is called long-term potentiation (LTP), and has been regarded as a neuronal correlate with learning and memory. Features of LPT in Schaffer collateral-CA1 neuron are calcium-dependency, input-specificity, cooperativity and sensitivity to blockers of N-methyl-D-aspartate (NMDA) receptors. These features can be explained by properties of NMDA receptors. LTP in mossy fiber-CA3 neuron has features different from those in field CA1: It is insensitive to blockers of NMDA receptors and does not show cooperativity. Quantal analysis of transmission through mossy fiber synapses before and after generation of LTP reveals that LTP resulted from facilitated release of transmitter. Participation of the metabotropic glutamate receptor is suggested.

Animals↗
PubMed1990

Effects of seizures on learning, memory, and behavior in the genetically epilepsy-prone rat.

To determine whether frequent seizures can cause deficits in learning and behavior, immature genetically epilepsy-prone rats (GEPRs) were subjected to 66 audiogenic stimulations (Group 1). GEPR littermates were handled and placed in the sound chamber but were not stimulated (Group 2). Group 3 comprised genetically epilepsy-resistant rats (GERRs) who received audiogenic stimulations but had no seizures. After 3 weeks of stimulations the rats were tested for learning, memory, and behavior using the T-maze, water maze, open field activity test, home cage intruder test, and handling test. When compared with the control GEPRs and GERRs, Group 1 rats reached criteria less frequently in the T-maze, required longer times to find the platform in the water maze, and were less active in the open field activity test, less aggressive in the home cage intruder test, and more irritable and aggressive in the handling test. This study demonstrates that frequent, brief seizures in immature animals result in significant detrimental changes in learning, memory, activity level, and behavior.

Acoustic Stimulation↗
PubMed2026

Activity-dependent DNA methylation and demethylation: epigenetic regulators of learning and memory.

Learning and memory are fundamental cognitive processes that rely on activity-dependent epigenetic mechanisms to shape synaptic and neuronal plasticity. Among these, DNA methylation and demethylation have emerged as pivotal regulators that convert transient neural activity into enduring transcriptional programs. In mammals, DNA methylation marks include 5-methylcytosine (5mC) as well as the less well-established N6-methyladenine (6mA) and the more enigmatic N4-methylcytosine (4mC). Compared with 5mC, the abundance, genomic distribution, and regulatory role of 6mA and 4mC remain incompletely defined, partly due to low abundance and technical challenges, yet these non-canonical marks may provide an additional regulatory layer in specific biological contexts. Accordingly, this review focuses on the best-characterized pathway in the nervous system, 5mC and its activity-regulated oxidative turnover. This system comprises a dynamic spectrum of cytosine modifications, including 5mC, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC), orchestrated by distinct enzyme families such as DNMTs, TETs, and TDG. We review current insights about how these regulators shape activity-induced gene expression programs underlying learning and memory, and we discuss how dysregulated DNA (de) methylation contributes to impaired transcriptional control and cognitive decline in neurodegenerative diseases, particularly Alzheimer's disease. Finally, we highlight recent advances in high-resolution mapping technologies for DNA modifications, which are expanding our ability to resolve cell type- and locus-specific epigenetic dynamics in the brain. A deeper understanding of these pathways may inform targeted strategies to preserve or restore cognitive function in neurological disorders.

Alzheimer’s disease↗
PubMed1987

Effects of standardized ginseng extract on learning, memory and physical capabilities.

Standardized ginseng extract (G115, Pharmaton, Lugano) was administered orally at doses of 3, 10, 30, 100 and 300 mg/kg for 10 days as ten rats were used with each dose. With the "shuttle-box" method for active avoidance most pronounced effect on learning and memory was obtained by the dose of 10 mg/kg. With the "step-down" method for passive avoidance the dose of 30 mg/kg significantly improved retention. In the staircase maze training with positive (alimentary) reinforcement only the dose of 10 mg/kg significantly improved learning and memory. The dose of 100 mg/kg greatly increased the locomotor activity of mice. The results show that ginseng at appropriate doses improves learning, memory and physical capabilities. Bell-shaped dose-effect curves, reported with other nootropic drugs, were obtained.

Animals↗
PubMed1991

Memory, learning and neuromediators.

We consider a model of a neural network where the individual cells interact only by releasing and absorbing the molecules of a neuromediator. We show that such a system can realize the function of associative memory. A learning mechanism based on the chemotaxis is proposed and numerically investigated.

Association Learning↗
PubMed1991

Cholinergic mechanisms in learning, memory and dementia: a review of recent evidence.

The discovery in the late 1970s that cholinergic neurons in the basal forebrain degenerate in Alzheimer's disease (AD) greatly accelerated research on the role of cholinergic mechanisms in learning and memory. As is often the case in science, the early enthusiasm for the cholinergic hypothesis has been tempered by the results of subsequent research. Although there is substantial pharmacological evidence that unspecified cholinergic systems in the brain play important roles in some forms of learning and memory, recent findings in humans indicate that antimuscarinic drugs do not model the deficits seen in AD. In addition, the goal of elucidating the functions of these basal forebrain neurons in animals has proved to be difficult and is yet to be achieved. Despite substantial effort, therefore, the cognitive and behavioral consequences of cholinergic pathology in AD remain unknown. Under these circumstances, attempts to develop cholinergic pharmacotherapies for these deficits in AD are based on questionable assumptions.

Animals↗
PubMedDate not supplied

[Interrelationship between immunologic and neurologic memory: learning ability of rats during immunostimulation].

Studies have been made on the effect of an immunostimulator - the complete Freund's adjuvant - upon the learning ability in Wistar rats for visual discrimination using food-obtaining and avoidance of the electric shock techniques. Injection of the adjuvant significantly increases learning ability provided negative reinforcement technique is used, but inhibits the former under the conditions of positive reinforcement. Analysis of the extinction of the conditioned reflexes yielded similar results. Possible relation of immunogenesis to the formation of memory is discussed.

Animals↗
PubMed1991

Learning, memory and the brain.

Human and non-human animals acquire information about the world through the process of learning, and store that information as memory. Yet central as the storage process is to adaptive behaviour, progress in understanding its neural bases has been slow and only recently efforts have shown clear signs of being successful. The knowledge that comes from this progress strongly suggests that different kinds of learning involve different neural circuits and accordingly involve different memory systems. Indeed, it is becoming increasingly clear that multiple memory systems may be a fundamental part of the design of the vertebrate brain. It has long been supposed that learning leads to the formation, or to the strengthening of particular pathways in the brain. Once formed, or strengthened in this way a pathway was viewed as a 'trace' or 'engram' 'representing' the particular experience or relationship which had been learned. There is substantial evidence that neural pathways, especially synaptic connectivity, can be modified by experience-as by rearing rats in an 'enriched' environment with other rats rather than rearing them in isolation--as well as by modifying the diet or by depriving young rats of their thyroid gland. This evidence demonstrates that the central nervous system is plastic, but provides no hint that such plasticity is involved in learning. The evidence that synaptic plasticity is indeed involved in learning and memory is relatively recent.

Animals↗
PubMed1985

Cellular mechanisms of learning, memory, and information storage.

In Table 1, we summarize what is convincingly demonstrated to date for the major vertebrate and invertebrate model systems attempting to elucidate cellular mechanisms of associative learning. Two major concerns are the adequacy of the behavioral demonstrations and the completeness and extent of the accompanying neurophysiology. In addressing the issue of behavior, it is important to define clearly which criteria are both necessary and sufficient to infer the involvement of an associative-learning process. Similarly, it is also important to distinguish among those primary characteristics of associative learning in general, and those secondary or tertiary features that serve to define various subclasses. In our view, it would be unreasonable to require that any given preparation exhibit all the defining features of classical conditioning, for example, in order to qualify as a "legitimate" instance of associative learning. This is especially true if the goal is to understand the more general, rather than the specific, mechanisms involved in associative learning. Hence, we emphasize the following as primary features of learned behavior: pairing specificity, stimulus specificity, long-term retention (arbitrarily defined as lasting for at least 24 hr), a moderate degree of reversibility by subsequent experience (e.g. extinction), and demonstrations that nonassociative-learning processes cannot account for features a-c. Where appropriate, we also identified other interesting features of the learned behavior. It is apparent from the table that a major unresolved issue for most of the preparations is the extent to which the behavioral changes are exclusively associative. This is no less true for the vertebrate preparations than it is for the invertebrates. The clearest example of an exclusively associative behavioral change is the rabbit NMR. The learning-produced changes in the invertebrate preparations were all shown, to varying degrees, to be pairing specific. Yet a major unresolved issue is the degree to which apparent examples of associative-learning reflect complex interactions among basically nonassociative-learning processes. The core issue is really quite simple: Does the associative training procedure result in the acquisition of new or qualitatively different behavior; and is there a strict requirement for an associative relation? In addressing the adequacy of the neurophysiological analyses, the major issue is that of localization. Logically, there are two components to this.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Effect of amino acid supplementation to a low-protein diet on brain neurotransmitters and memory-learning ability of rats.

The supplementation of methionine and threonine to a 10% soy protein isolate diet caused sharp decreases in the concentrations of brain tryptophan, serotonin and 5HIAA (5-hydroxyindole acetic acid) (e.g., in the hypothalamus, hippocampus, amygdala, locus coeruleus and brain stem). The serum tryptophan ratio (i.e., the ratio of the serum concentration of tryptophan to the sum of the concentrations of other large neutral amino acids, such as tyrosine, phenylalanine, leucine, isoleucine, valine and methionine) significantly decreased. The changes in catecholamines were small on the supplementation of amino acids to the soy protein diet. In the brightness-discrimination learning test, the number of total responses (R+, correct; R-, incorrect) of rats fed the amino acid-supplemented diet increased as compared with that of rats fed the nonsupplemented diet. The correct response ratio in the primary learning test did not change, but in the reverse learning test, the response ratio of rats fed the amino acid-supplemented diet increased. Therefore, it may be considered that the learning ability is correlated with the nutritional state.

Amino Acids↗
PubMed1975

Disruption of state-dependent learning (memory retrieval) by emotionally-important stimuli.

State-Dependent Learning (SDL) occurs when a response learned in a particular drug stste does not transfer to another drug state. SDL was demonstrated and disrupted in a modified T-maxe escape learning task, using male hooded rats. SDL groups were trained each day in one drug state (either Librium, 40 mg/kg or sterile water) and then given non-shock test trials in both drug states. SDL Ss showed drug-dependent retention since they turned randomly in opposite-state test trials and significantly above random level (P greather than 0.02) when in the training drug state. For the Transfer Ss, 1k Hz tone was simultaneously paired with foot shock in training and continued to be sounded on every non-shock test trial. Transfer Ss turned in the training direction regardless of drug state. Drug-dependence in the SDL groups and transfer in the Transfer groups were also demonstrated in response latencies. The tones were emotional memory prompters initiating some process that mediated transfer between drug states. The theoretical importance of these results were discussed in relation to energizing and directing functions of emotions and symmetrical and asymmetrical transfer.

Acoustic Stimulation↗
PubMed1978

[Effects of lithium on learning, memory, and mood (author's transl)].

In a double-blind study the effects of a 14-day lithium medication (dosage: 24 mval/d to 36 mval/d) were investigated. The subjects were 24 healthy male volunteers. The effect of lithium on their mood, ability to learn nouns, and memory of the words learnt was measured after 2 h and 14 days. In spite of a relatively low mean plasma lithium level on the 14th day (0.54 +/- 0.15 mmol/l), the lithium volunteers assessed themselves after 2 weeks of treatment as significantly less relaxed, less active, less socially involved, more bored, and more tired than the placebo group. As to learning, the lithium group showed only a slight impairment of performance compared to the placebo group. As to memory, there was only a significant difference in free recall over two weeks: the lithium group remembered fewer words than the placebo group. Additional motivation of free recall over 2 h was uneffective. It is discussed whether lithium changes spontaneous initial action and thereby the will to act. This could be interpreted as a change in the production of the characteristics of experience and behaviour.

Adult↗