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 523 records · Page 29Linked to original sources
PubMed1997

Inhibitory learning and memory in newborn rats.

Firstly, the noetic value of the ontogenetic approach to the problems of learning and memory is emphasized; then the heterochrony and uneven time course of the development of neural systems are accentuated, which fully holds for the basic cognitive functions. Contrary to a broadly accepted opinion, that inhibitory learning develops later in the ontogeny, using a special method of passive avoidance (with gentle air flow inciting the new-born animal to move), the ability of new-born rats to learn an inhibitory reaction even several hours after delivery and remember it for 24 hr has been proven; special control experiments have excluded any possibility that it is a non-specific reaction. To get it, the specific features of the neonatal organism are to be considered and its functional capabilities not to be overlooked. This conditioned reaction as well as its 24 hr memory develops with a temporary reversal during several postnatal days, needing decreasing numbers of trials to meet the criteria. In the analysis of their mechanisms, it has been shown that adequate functioning of peripheral receptor zones providing afferent inputs from somatosensory areas of the conditioned stimulus is considerably involved in their establishment. Increased dendritic branching has been found in hippocampus and Meynert nucleus the following day after learning in the neonatal period. Special attention is devoted to the involvement of transmitters and/or modulators; the action of acetylcholine, noradrenaline, dopamine and nitric oxide has been discovered during the first postnatal hours; their application after meeting criteria displays a time and age dependent effect with a general characteristic of memory improvement. Neonatal learning under nitric oxide influence changes nitric oxide-synthase content in the brain. Increasing dopamine and nitric oxide availability in the brain improves both learning and memory, and their joint application positively alleviates these phenomena further. Dopamine and its D1 receptor agonists counterbalance decreased nitric oxide after nitric oxide synthase blockade; increased nitric oxide in brain and dopamine receptor antagonists similarly counterbalance each other.

Animals↗
PubMed1997

Mechanism of colchicine impairment on learning and memory, and protective effect of CGP36742 in mice.

Fourteen days after hippocampal microinfusion with colchicine (COL), learning and memory ability of mice was significantly impaired, while glutamate (Glu), gamma-aminobutyric acid (GABA), Glu/GABAB and GABAB receptor levels in the cortex and/or the hippocampus were significantly changed. After treatment with a GABAB receptor antagonist, CGP36742, learning and memory impairment caused by COL could be significantly improved, and the above indices in brain regions reversed. These results suggest GABAB antagonists may have therapeutic value in the treatment of Alzheimer's disease.

Animals↗
PubMed1995

[Neurobiology of learning and memory and anti-dementia drug].

Discoveries of long-term potentiation and immediate early gene in the central nervous system have enabled new developments in experiments on learning and memory. These experiments are conducted in many kinds of animals with different procedures, physiology, chemistry and pharmacology. However, there is still some confusion when these various procedures are discussed. Memory is defined as information storage of an animal's previous experiences. The memory induces changes in behavioral performance. This means that memory must be observed in whole animals, and one question that can occur is how does long-term potentiation, for example, correlate with memory. Furthermore, memory has been divided into two major classifications, declarative and non-declarative, from the comparison of amnesias observed in humans and animals. The declarative memory can be observed in human subjects, but not in animals. This article presents a neuronal circuit concerning memory formation and some results obtained from benzodiazepines, and it discusses some problems encountered executing when experiments on learning and memory. In addition, the discussion speculates over the possibility for an "anti-dementia drug".

Animals↗
PubMed1987

Physiological and behavioural consequences of seizures induced in the rat by intrahippocampal tetanus toxin.

Injecting tetanus toxin into rat hippocampus induces a syndrome of intermittent generalized seizures which recurs for about one month. Following remission from their seizures, the rats exhibit very persistent impairments of learning and memory. Learning was impaired on a circular platform task and a spatial reference memory task, and evoked responses from the commissural-CA3 pyramidal cell system were depressed for up to 22 weeks after injection. There was no significant loss of pyramidal neurons because antidromic responses, evoked from other parts of the commissural fibre system, were not affected by the toxin treatment. The depression of these pyramidal neurons provides a reasonable physiological explanation for the learning impairment. These results suggest that impairments of neuronal function can be significant factors in the development of interictal behavioural abnormalities.

Animals↗
PubMed2004

Learning and memory in Holocaust survivors with posttraumatic stress disorder.

BACKGROUND: Impairments in explicit memory have been observed in Holocaust survivors with posttraumatic stress disorder. METHODS: To evaluate which memory components are preferentially affected, the California Verbal Learning Test was administered to Holocaust survivors with (n = 36) and without (n = 26) posttraumatic stress disorder, and subjects not exposed to the Holocaust (n = 40). RESULTS: Posttraumatic stress disorder subjects showed impairments in learning and short-term and delayed retention compared to nonexposed subjects; survivors without posttraumatic stress disorder did not. Impairments in learning, but not retention, were retained after controlling for intelligence quotient. Older age was associated with poorer learning and memory performance in the posttraumatic stress disorder group only. CONCLUSIONS: The most robust impairment observed in posttraumatic stress disorder was in verbal learning, which may be a risk factor for or consequence of chronic posttraumatic stress disorder. The negative association between performance and age may reflect accelerated cognitive decline in posttraumatic stress disorder.

Aged↗
PubMed1992

Verbal learning and memory in language impaired children.

The present study investigated patterns of verbal learning and memory in Language Impaired (LI) and normal children, using the California Verbal Learning Test--Children's Version. The LI children showed a normal immediate memory span; however, they were impaired in the total number of correct responses that they generated across repeated trials. They reported significantly more perseverations, but not intrusions, relative to the controls. The LI children were not impaired on a delayed free recall task, but they were significantly impaired relative to the controls on semantically cued recall. The implications of these findings for future research and for remediation are discussed.

Child↗
PubMed1995

The effects of D-cycloserine and MK-801 on the performance of rats in two spatial learning and memory tasks.

The present study was undertaken to investigate the effects of modulation of the N-methyl-D-aspartate (NMDA) receptor on learning and memory. Thus, the performance of rats treated with D-cycloserine, a partial agonist at the glycine recognition site of the NMDA receptor complex, and MK-801, a noncompetitive NMDA receptor antagonist, either alone or concurrently were assessed in radial arm maze and water maze tasks. Administration of MK-801 (0.1 mg/kg, i.p.) impaired acquisition in the water maze (increased escape latency and distance) and working memory in the radial arm maze (increased re-entries) in rats. Moreover, in the radial arm maze, MK-801 disrupted locomotion (increased latencies and decreased arm entries per minute) and impaired the acquisition of reference memory (increased number of errors) performance of rats. D-Cycloserine (0.03, 0.3, 1.0, 3.0, 10 mg/kg, i.p.) had no effects on acquisition or memory performance of control or MK-801-treated rats in either of these tasks. However, D-cycloserine (0.03, 0.3, 3.0 mg/kg) reversed the MK-801-induced disruption in locomotion. Furthermore, 3.0 mg/kg D-cycloserine increased behavioral activity and also decreased the time needed to complete the task in control animals. To conclude, our results suggest that the consequences of NMDA receptor modulation on learning and memory processes and sensorimotor functions may be functionally different or have distinct anatomical locations.

Adaptation, Psychological↗
PubMedDate not supplied

The effects of the hormones of peripheral endocrine glands on the processes of behavior, learning, and memory.

The effects of systemic administration of thyroid, adrenal cortex, and sex hormones on learning ability, memory trace retention, and behavior were compared in male rats. These studies showed that thyroid, corticosteroid, and sex hormones had no effect on passive learning. Excess quantities of sex hormones disrupted active learning and subsequent reproduction of received information; an excess of thyroid hormone improved the acquisition and retention of the active avoidance habit. Increases in the levels of adrenal cortex hormones worsened active learning and the retention of memory traces, and also increased the level of behavioral activity.

Adrenal Cortex Hormones↗
PubMed2006

Learning and memory: traditional and systems approaches.

The aims of the present work were to consider the characteristics of learning and memory from the point of view of a systems approach and to compare this view with the traditional approach. Neuron activity is regarded not as a response to the synaptic influx resulting in excitation but as a means of altering the cell's relationship with its environment, whose "action" is to eliminate discordance between the cell's "needs" and its microenvironment. The neuronal mechanisms of learning and consolidation of memory are regarded not as formation of a stable increase in the efficiency of synaptic transmission in circuits of connected neurons, but as a system genesis event which confers new system specializations on neurons which do not have to be directly connected synaptically. The roles of the processes of selection, reconsolidatory modification of previously formed memories, gene activation, neurogenesis, and apoptosis in systems genesis occurring both in normal and pathological conditions are discussed. Individual development is regarded as a sequence of system genesis events. The systems approach is applied to the phenomenon of long-term potentiation. In conclusion, a scheme including different types and stages of memory formation is presented.

Animals↗
PubMed1988

Verbal memory and learning in unilateral posterior cerebral infarction. A report on 30 cases.

Unilateral posterior cerebral infarction, sparing memory-related structures in the diencephalon, may represent a means of investigating the role of hippocampal afferents and the parahippocampal areas in memory processing. Among 30 patients with unilateral posterior cerebral infarction a group of 12 subjects with left-sided lesions suffered from marked verbal memory and learning dysfunction, whereas the remaining subjects with left or right-sided lesions showed no obvious memory deficit. The impairment was most prominent for verbal learning tasks, while recall of isolated and complex verbal information appeared to be less affected. In some cases the memory disturbance could be detected up to one year after the causative event. Analysis by CT scanning revealed a coincidence of mnestic disturbances with lesions around the left collateral sulcus affecting the posterior parahippocampal gyrus and the collateral isthmus. The latter term refers to the fibre stem of the medial temporal lobe limited by the floor of the lateral ventricle and the depth of the collateral sulcus. Through this bottle-neck, bidirectional fibres run between the posterior parahippocampal gyrus and different sensory-specific and multimodal association areas. A lesion within the collateral isthmus or, more particularly, a combined lesion of the collateral isthmus and the posterior parahippocampal gyrus, deprives the hippocampus itself of its main afferent projection source and, on the other hand, prevents dissemination of the hippocampal output to widespread neocortical areas. It cannot be excluded, at least in some cases, that small lesions in the fimbria-fornix route, in the retrosplenial cortex or in the hippocampal formation itself also contribute to the memory and learning dysfunction. However, these small lesions, so far as they could be detected by CT scanning, were present in patients with and without memory disturbances.

Adult↗
PubMed2006

The effects of chronic administration of ethosuximide on learning and memory: a behavioral and biochemical study on nonepileptic rats.

Long-term use of antiepileptic drugs is common in the treatment of epilepsy. Clinical reports exist of cognitive impairment attributed to antiepileptic drugs. Hence, this study evaluates the effect of chronic administration of one antiepileptic drug, ethosuximide, on spatial and fear learning and memory in nonepileptic rats. High performance liquid chromatography with electrochemical detection was used for quantification of glutamate, glycine, taurine, gamma-aminobutyric acid, dopamine, and serotonin in the frontal cortex and hippocampus to elucidate the neurobiological basis of the effect of ethosuximide on learning and memory. We found that 21 days of ethosuximide treatment produced negative effects on fear memory (passive avoidance) at all doses (100, 200 and 250 mg/kg body weight), but had no effect on spatial learning (T-maze). Fear memory impairment was associated with decreased hippocampal dopamine levels. Ethosuximide (at all doses) had a minimal effect on the GABAergic and glutamatergic systems in all brain regions studied, with the exception of elevated levels of gamma-aminobutyric acid in the frontal cortex with the 250 mg/kg body weight dose. We have shown that long-term administration of ethosuximide adversely affects fear memory, but does not affect spatial learning and memory.

Animals↗
PubMedDate not supplied

Learning and memory in rats gestationally and lactationally exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

Recently we reported that in utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or coplanar polychlorinated biphenyls (PCBs) resulted in a reduction of errors on a radial arm maze (RAM) working memory task. The effect was more pronounced in males than in females. In this study, we further investigated the effects of in utero and lactational exposure to TCDD on learning and memory by testing male and female TCDD-exposed rats on three different spatial learning and memory tasks: the RAM, the Morris water maze (MWM), and spatial discrimination-reversal learning (RL), as well as on a nonspatial learning task, visual RL. Time-mated Sprague-Dawley rats were gavaged with either TCDD (0.1 microg/kg/day) or corn oil vehicle on gestation days 10-16. Litters were culled to eight on day 2 and weaned on day 21. Beginning on day 80, one male and one female from each litter were tested on the same RAM working memory task used in the previous study. Again, the TCDD-exposed male rats displayed a pronounced decrease in errors relative to control males. Following the RAM testing, the same animals were tested on the MWM, but no differences between the exposed and control rats were observed. Another male and female from each litter were tested on spatial RL on a T-maze. There were no differences between the exposed and control rats on this task. Following spatial RL, the same rats were tested on visual RL on the same maze. The exposed animals did not differ from controls on original learning, but took more trials to reach criterion on the first and second reversals. These results demonstrate a reliable, but task-specific, facilitation of spatial learning and memory in male rats exposed to TCDD during gestation and lactation. In contrast, both male and female TCDD-exposed rats showed a deficit in learning on the visual RL task. This pattern is consistent with that seen in earlier monkey studies. Perinatally TCDD-exposed monkeys were facilitated on certain spatial tasks, but impaired on visual RL tasks.

Analysis of Variance↗
PubMed1998

Beta-amyloid(Phe(SO3H)24)25-35 in rat nucleus basalis induces behavioral dysfunctions, impairs learning and memory and disrupts cortical cholinergic innervation.

Long-term behavioral effects, changes in learning and memory functions and aberrations of cholinergic fibers projecting to the parietal cortex were investigated after bilateral injections of beta-amyloid(Phe(SO3H)24)25-35 peptide in rat nucleus basalis magnocellularis (nbm). The beta-amyloid peptide used in these experiments contained the original beta-amyloid 25-35 sequence which was coupled to a phenylalanine-sulphonate group at position 24. This additional residue serves as a protective cap on the molecule without influencing its neurotoxic properties and results in water-solubility, stability and low rates of peptide metabolism. In this paper, home cage, locomotor and open-field activities, passive shock-avoidance and 'Morris' water maze learning abilities were assessed throughout a 35-day survival period. Subsequently, acetylcholinesterase (AChE) histochemistry was used to visualize alterations of parietal cortical cholinergic innervation. In response to the neurotoxic action of beta-amyloid(Phe(SO3H)24)25-35, a progressive hyperactivity developed in the rats in their home cages which were maintained throughout the 5-week post-injection period. This was accompanied by a significant hypoactivity in the novel environment of a locomotor arena. Beta-amyloid(Phe(SO3H)24)25-35-treated animals showed greatly impaired cortical memory functions in the step-through passive shock-avoidance paradigm, while spatial learning processes remained unaffected. Moreover, beta-amyloid(Phe(SO3H)24)25-35 injections in the nucleus basalis suppressed explorative behavior in rats and inhibited conditioned stress responses 28 days after surgery. Reductions of cortical cholinergic (AChE-positive) projections provided anatomical substrate for the behavioral changes. This indicated extensive, long-lasting neurodegenerative processes as a result of beta-amyloid(Phe(SO3H)24)25-35 infusion.

Acetylcholinesterase↗
PubMed2001

Conditioned taste aversion as a learning and memory paradigm.

Conditioned taste aversion (CTA) is a well established learning and memory paradigm in rats and mice that is considered to be a special form of classical conditioning. Rodents--as well as many other species including man--learn to associate a novel taste (CS) with nausea (US), and as a consequence avoid drinking fluid with this specific taste. In contrast to other types of classical conditioning, even CS-US intervals lasting several hours lead to an aversion to the gustatory CS. With increasing CS-US delay duration, however, the aversion against the CS gradually decreases. Mice differ from rats in their reaction to the CS as well as the US. They tolerate a much higher concentration of saccharin and they do not show any clear signs of nausea when injected with the US. Advantages of this task are its relative independence of motor behavior, well described pathways for the CS and partly the US, and the wealth of available anatomical and pharmacological data implying several brain structures (e.g. parabrachial nucleus, amygdala, insular cortex), neurotransmitters and their receptors (e.g. cholinergic system, NMDA-receptors), and cellular processes (e.g. expression of immediate early genes, Ras-MAP kinase signaling pathway, CREB phosphorilation, protein tyrosine phosphorilation, protein synthesis) in CTA. The CTA paradigm has also been successfully used to phenotype mouse mutants.

Animals↗
PubMed1998

Developmental effects on odor learning and memory in children.

The child version of the California Odor Learning Test (COLT) was designed to assess cognitive functioning in impaired and healthy children. The COLT's rationale was based on two assumptions. First, measures of cognitive functioning are a good index of severity or extent of brain damage if compared between normal and clinical populations. Second, the cognitive-mediated tasks of verbal odor recall, recognition and identification were suitable to evaluate cognitive functioning. The focus of this study was to determine the COLT's ability to detect developmental differences in odor learning and memory. The participants were 51 healthy children who were twice administered the COLT with a weekly delay between tests. They were ascribed to two age-groups (7-10 and 11-15 years old) according to levels of cognitive development. The COLT employed 22 common odors and included two sessions. In the first session, children learned two sets of six odors. The first set was presented three times, the second one once, during a single learning episode. Following learning, children recalled the odors of the first set by name at free recall and category-cued recall. The second session included the following tasks: long-term free odor recall and category-cued odor recall, odor recognition-memory and verbal odor identification. A series of analyses of variance (ANOVAs, p < 0.05) with age as between-subject variable and repeated measurements on recall revealed significant differences between the two groups on the number of odors correctly recalled by name both at free recall, category-cued recall, recognition and identification. There were differences in false alarms at odor recognition between the two groups. Children from both groups benefited from a learning effect over odor trials. A gender effect was found for odor free recall at retest. These results suggest that the COLT has the potential to serve as a useful tool in the assessment of cognitive functioning in children.

Adolescent↗
PubMed1997

A mouse model for the learning and memory deficits associated with neurofibromatosis type I.

Neurofibromatosis type I (NF1) is one of the most commonly inherited neurological disorders in humans, affecting approximately one in 4,000 individuals. NF1 results in a complex cluster of developmental and tumour syndromes that include benign neurofibromas, hyperpigmentation of melanocytes and hamartomas of the iris. Some NF1 patients may also show neurologic lesions, such as optic pathway gliomas, dural ectasia and aqueduct stenosis. Importantly, learning disabilities occur in 30% to 45% of patients with NF1, even in the absence of any apparent neural pathology. The learning disabilities may include a depression in mean IQ scores, visuoperceptual problems and impairments in spatial cognitive abilities. Spatial learning has been assessed with a variety of cognitive tasks and the most consistent spatial learning deficits have been observed with the Judgement of Line Orientation test. It is important to note that some of these deficits could be secondary to developmental abnormalities and other neurological problems, such as poor motor coordination and attentional deficits. Previous studies have suggested a role for neurofibromin in brain function. First, the expression of the Nf1 gene is largely restricted to neuronal tissues in the adult. Second, this GTPase activating protein may act as a negative regulator of neurotrophin-mediated signalling. Third, immunohistochemical studies suggest that activation of astrocytes may be common in the brain of NF1 patients. Here, we show that the Nf1+/- mutation also affects learning and memory in mice. As in humans, the learning and memory deficits of the Nf1+/- mice are restricted to specific types of learning, they are not fully penetrant, they can be compensated for with extended training, and they do not involve deficits in simple associative learning.

Acoustic Stimulation↗
PubMed2001

[Effect of ginsenoside Rg1 on learning and memory impairment induced by beta-amyloid peptide(25-35) and its mechanism of action].

AIM: To study the effect of ginsenoside Rg1 on the learning and memory impairment in mice induced by aggregated beta-AP(25-35). METHODS: Mice were administered Rg1(5, 10 mg.kg-1, i.p.) for 10 d and control mice received daily i.p. injections of saline after the intracerebroventricular injection of aggregated beta-AP(25-35). After the final treatment, passive avoidance and performance in the Morris water maze (MWM) were assessed. and the activity of cortical and hippocampal ChAT and AchE were detected after the final behavior test. RESULTS: Ginsenoside Rg1 (5, 10 mg.kg-1, i.p.) significantly ameliorated the learning and memory impairment induced by beta-AP(25-35). Rg1 (5, 10 mg.kg-1) decreased the latencies and swim distances of mice to reach a hidden platform and improved the corresponding changes in search strategies occurred in the Morris water maze, and Rg1 (10 mg.kg-1, i.p.), increased step-through latencies also. Biochemical analysis showed that Rg1 (5, 10 mg.kg-1, i.p.), prevented the cortical and hippocampal ChAT activity decline induced by beta-AP(25-35), and showed inhibition of the activity of AchE, although beta-AP(25-35) showed no effect on the cortical and hippocampal AchE activity. CONCLUSION: These data showed that ginsenoside Rg1 significantly improved the learning and memory impairment induced by beta-AP(25-35), and this effect could be attributed to its inhibition of AchE and increase of ChAT activity.

Acetylcholinesterase↗
PubMed2006

The in vivo synaptic plasticity mechanism of EGb 761-induced enhancement of spatial learning and memory in aged rats.

It has not been uniform to date that the Ginkgo biloba extracts enhance cognitive function in aged animals, and the mechanisms of action remain difficult to elucidate. In this study, the Morris water maze task and electrophysiological methods were used to study the effects of repeated daily administration of EGb 761, a standardized extract from G. biloba leaves, on hippocampal-dependent spatial learning and memory and synaptic plasticity of aged rats. The adult subjects perform the Morris water maze task better than aged rats, as a cellular mechanism, the hippocampal long-term potentiation (LTP) elicited from adult animals is robust (139.29+/-2.7%). In addition, the spatial learning and memory of aged rats that had been fed on an EGb 761-supplemented diet (60 mg kg(-1)) for 30 days were significantly better than those of control aged rats. The magnitude of LTP (116.63+/-3.6%) recorded in vivo from the hippocampus CA1 area of aged rats was significantly enhanced by EGb 761 (60 mg kg(-1)). In conclusion, the spatial learning and memory of aged rats is worse than that of young subjects, and EGb 761, acting as a 'cognitive enhancer', has benefit on synaptic plasticity and cognition in aged rats. The present data further confirmed that enhancement of synaptic plasticity of the hippocampus might ameliorate the deficit in spatial learning and memory in aged rats.

Aging↗