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PubMed2002

[Effect of puerarin on learning-memory behavior and synaptic structure of hippocampus in the aging mice induced by D-galactose].

AIM: To study the effects of puerarin on learning-memory behavior of aging mice induced by D-galactose and its possible mechanism of action. METHODS: The aging mice were induced by s.c. 0.12 g.kg-1 D-galactose for 6 weeks. The aging mice were treated with three doses of puerarin once a day for 5 weeks. The spontaneous behavior and the learning memory behavior were tested in the aging mice using open field and Y-maze at the next day after the last treatment. The structure of Gray I synaptic interface in the CA3 area of the hippocampus was quantitatively analyzed by electronic microscope and computer image processing appliance. RESULTS: Compared with the D-galactose control group, puerarin (60 mg.kg-1) was shown to increase significantly the spontaneous behavior and explorative response in the open field, and improve remarkablely the learning and memory ability of the aging mice induced by D-galactose. Meanwhile, the thickness of post-synaptic density (PSD) was increased, and the width of the synaptic cleft in the hippocampus CA3 area was shortened. CONCLUSION: Puerarin showed an improvement effect against the memory impairment in the modelling aging-mice induced by D-galactose. A pathological alteration of synaptic interface structure in hippocampus of the mice may be involved in the effect.

Aging↗
PubMed2005

Abnormal expression of epilepsy-related gene ERG1/NSF in the spontaneous recurrent seizure rats with spatial learning memory deficits induced by kainic acid.

Previous epilepsy-related gene screen identified a spontaneous recurrent seizure (SRS)-related gene named epilepsy-related gene (ERG1) that encodes N-ethylmaleimide-sensitive fusion protein (NSF). To explore whether spatial learning memory deficits are relevant to SRS and whether hippocampal NSF expression is altered by SRS, we used the kainic acid (KA)-induced epilepsy animal model. SRS was monitored for 3 weeks after injection of a single convulsive dose of KA. KA-treated rats with SRS, KA-treated rats without SRS, and saline-treated rats were then measured in Morris water maze. In this spatial learning task, KA-treated rats with SRS performed poorer compared to those without SRS and those treated with saline. During the subsequent probe trials, KA-treated rats with SRS spent less swim path and time in the target quadrant but more swim path and time in the opposite quadrant, and showed fewer platform crossings. Moreover, in situ hybridization and immunohistochemistry showed that both ERG1/NSF mRNA and NSF immunoreactive expression were down-regulated in the CA1 and dorsal dentate gyrus cells (dDGCs) of the hippocampus, and interestingly, tyrosine hydroxylase (TH) immunoreactive dopamine (DA) neurons were lost in ventral tegmental area (VTA) in the KA rats with SRS. These data demonstrate that SRS impairs spatial learning memory and suggest that the down-regulation of NSF expression pattern in the hippocampus and the loss of DA neurons in VTA might contribute to the spatial learning memory deficits induced by SRS.

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↗
PubMed2003

[Effect of tetramethylpyrazine on learning, memory and cholinergic system in D-galactose-lesioned mice].

OBJECTIVE: To explore the effect of tetramethylpyrazine on learning, memory, and cholinergic system in D-galactose-lesioned mice. METHODS: C57BL/6J mice were given subcutaneous injection of 2% D-galactose for 40 days (100 mg.kg-1.d-1). Normal saline, tetramethylpyrazine (TMP) and Huperzine A (HupA) were given respectively by intragastric administration in different study groups from the third week on. Learning and memory ability were tested by Morris water maze for 5 days at the sixth week. Acetylcholinesterase (AchE) activity, the binding sites (Bmax) and the affinity (KD) of M-cholinergic receptor were determined. RESULTS: The learning and memory dysfunction, with lowered AchE activity and M-cholinergic receptor binding sites were found in the model group as compared with the normal control group. The tetramethylpyrazine, especially at the dose of 100 mg.kg-1.d-1, could markedly attenuate cognitive dysfunction, while elevate the lowered AchE activity (P < 0.05) and M-cholinergic receptor binding sites (P < 0.005) in the cerebral cortex of mice treated with D-galactose. CONCLUSIONS: The tetramethylpyrazine can significantly improve central cholinergic system function, and thus enhance the learning and memory ability in D-galactose-lesioned mice.

Acetylcholinesterase↗
PubMed2000

Role of corticotropin-releasing factor, vasopressin and the autonomic nervous system in learning and memory.

Learning and memory are essential requirements for every living organism in order to cope with environmental demands, which enables it to adapt to changes in the conditions of life. Research on the effects of hormones on memory has focused on hormones such as adrenocorticotropic hormone (ACTH), glucocorticoids, vasopressin, oxytocin, epinephrine, corticotropin-releasing factor (CRF) that are released into the blood and brain following arousing or stressful experiences. Most of the information have been derived from studies on conditioned behavior, in particular, avoidance behavior in rats. In these tasks, an aversive situation was used as a stimulus for learning. Aversive stimuli are associated with the release of stress hormones and neuropeptides. Many factors play a role in different aspects of learning and memory processes. Neuropeptides not only affect attention, motivation, concentration and arousal or vigilance, but also anxiety and fear. In this way, they participate in learning and memory processes. Furthermore, neuropeptides such as CRF and vasopressin modulate the release of stress hormones such as epinephrine. In turn, systemic catecholamines enhance memory consolidation. CRF and vasopressin are colocalized in neurons from the nucleus paraventricularis, which project to nuclei in the brainstem involved in autonomic regulation. The objective of this paper is to discuss the role of CRF, vasopressin, and the autonomic nervous system (ANS) in learning and memory processes. Both CRF and vasopressin have effects in the same direction on behavior, learning and memory processes and stress responses (release of catecholamines and ACTH). These neuropeptides may act synergistically or in a concerted action aimed to learn to adapt to environmental demands.

Animals↗
PubMed2000

Influence of diet and occlusal support on learning memory in rats behavioral and biochemical studies.

In order to verify the relationship between tooth loss and the learning memory in rat, male Wistar rats (25 weeks old) were divided into three separate groups: a control group (fed with a solid diet); a soft diet group (fed with a powder diet containing the same components as the solid one) and a molarless group (all molars were removed at 25 weeks and then fed with a powder diet). To evaluate both learning ability and memory, rats were tested with a one-way step through type of passive avoidance apparatus divided into light and dark chambers at 40-weeks. After the passive avoidance test, determination of acetylcholine (ACh) concentration of the cerebral cortex and hippocampus was performed. There was no significant difference between the molarless group and the control group in the response latency before the acquisition trails (non-stimulated period). At day 4 and 7 after the acquisition trials, the response latency of the molarless group was significantly shorter than that in the control group (p<0.05). The ACh levels of the molarless group in the cerebral cortex and hippocampus were significantly lower than that of the control group (p<0.05). It was apparent that tooth loss had an association with a loss of discriminative learning ability. This study suggested that the decrease of masticatory function caused by tooth loss leads to a decrease of ACh synthesis resulting in a learning memory disorder.

Acetylcholine↗
PubMedDate not supplied

Cdk5: a novel role in learning and memory.

Learning and memory are processes by which organisms acquire, retain and retrieve information. They result in modifications of behavior in response to new or previously encountered stimuli thereby enabling adaptation to a permanently changing environment. Protein phosphorylation has long been known to play a key role in triggering synaptic changes underlying learning and memory. Although intracellular phosphorylation and dephosphorylation is orchestrated by a complex network of interactions between a number of protein kinases and phosphatases, significant advances in the understanding of neuronal mechanisms underlying learning and memory have been achieved by investigating the actions of individual molecules under defined experimental conditions, brain areas, neuronal cells and their subcellular compartments. On the basis of these approaches, the cyclic AMP protein kinase (PKA), protein kinase C (PKC) and extracellularly regulated protein kinases 1 and 2 (Erk-1/2) have been identified as the core signaling pathways in memory consolidation. Here we review recent findings demonstrating an important novel role for Cdk5 in learning and memory. We suggest that some of the well-characterized roles of Cdk5 during neurodevelopmental processes, such as interactions with distinct cytoplasmic and synaptic target molecules, may be also involved in synaptic plasticity underlying memory consolidation within the adult central nervous system.

Animals↗
PubMed2004

Emerging targets for the pharmacology of learning and memory.

Learning and memory are dynamic processes associated with modifications in morphology, biochemistry and physiology of the nervous system, that can be analysed at different levels of biological organization. Within this context, changes correlated with cognitive processes are identifiable at distinct cellular and molecular loci of the nervous system. Synaptic plasticity represents an experience-dependent alteration of neuronal properties that subserve learning and memory, and for which a neuronal network can be considered as a candidate for being part of an engram. Multiple molecular systems at various levels of the signal transduction cascade, such as those involving receptors, second messengers and gene expression, may be linked to synaptic remodelling during cognitive processes. After a brief overview of the various facets of memory and the higher levels of cerebral organization (with special attention to the hippocampus), this review is devoted to the presentation of some novel potential therapeutic targets within the signal transduction cascade that might be considered for rational pharmacological intervention to improve learning and memory in both diseased and healthy individuals.

Animals↗
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&#x2019;s disease↗
PubMed1997

[Effects of new constituents L-6a and L-10 from leaves of Luffa cylinderica on learning, memory, and hippocampal somatostatin in rats].

AIM: To study the effects of two constituents L-6a and L-10 from the leaves of Luffa cylinderica Roem on learning, memory, and hippocampal somatostatin in rats. METHODS: The learning and memory in rats were determined using the passive avoidance response of shuttle-box, by i.c.v. Somatostatin in hippocampus was determined with immunohistochemical and images analyses. RESULTS: L-6a 25 micrograms raised memory-keeping activity (P < 0.05) in rats. L-6a 25 micrograms increased the surface density and number density of somatostatin-like immureactant (Som-LI) (P < 0.05). L-10 25 and 50 micrograms increased the surface density and number density of Som-LI (P < 0.05). CONCLUSION: L-6a 25 micrograms enhanced memory-keeping activity and increased the surface density and number density of Som-LI in rats. L-10 shows a tendency to enhance memory-keeping activity but no evident, but it increases the surface density and number density of Som-LI.

Animals↗
PubMed1982

Learning, memory, and transfer in profoundly, severely, and moderately mentally retarded persons.

Discrimination learning, memory, and transfer capacity were assessed in representative samples of institutionalized retarded persons in order to provide information on trainability. The 56 subjects were selected from moderately, severely, and two levels of profoundly retarded adults. They learned and relearned three successive two-choice discrimination problems. Generally, the higher functioning subjects, defined by IQ and adaptive behavior learned more rapidly than did the lower functioning subjects. Forgetting was related to IQ/adaptive behavior level. Interproblem transfer was negligible at all levels of retardation, but ceiling effects may have obscured positive transfer in the higher functioning groups. Backward learning curves revealed large differences between lower and higher functioning persons in the presolution trials, but once learning began even profoundly retarded subjects solved these problems as rapidly as did the moderately retarded subjects. Ten of the 56 subjects failed to learn all three problems.

Adult↗
PubMed1983

Behavioral changes in aging Aplysia: a model system for studying the cellular basis of age-impaired learning, memory, and arousal.

The marine mollusc Aplysia californica was used to examine the effects of age on simple forms of learning, memory, and arousal. We have found that aging impairs the long-term retention of habituation and prevents the acquisition of sensitization in the siphon withdrawal reflex. In addition, aging reduces arousal as evident in the heart rate component of the response to food stimuli. Our results are similar to the age-dependent alterations in the capacity for behavioral plasticity that have been reported in a variety of vertebrates, including man. These similarities suggest that the mechanisms underlying the effects of age on behavior and its modification may share common features across phyla and therefore might be studied to advantage in Aplysia whose central nervous system is especially accessible to cell biological approaches.

Aging↗
PubMed1996

Effects of aging and hypertension on learning, memory, and activity in rats.

A comparison between behavioral alterations induced by hypertension and aging was made in spontaneously hypertensive (SHR) and Wistar-Kyoto rats (WKY) of different ages (3-24 months old), trained to perform autoshaping learning and activity tasks. Food-deprived rats received autoshaping training sessions during 6 days; the animals were retrained 1 month later. Two weeks after autoshaping training, the animals were evaluated in the spontaneous activity task during 2 consecutive days. The results show an age-related decrease in learning, memory, and spontaneous activity. Independently of the age group compared, WKY, though showing lower activity, learned and retrieved more than SHR. Accordingly, the reductions in learning and memory were correlated with both aging and hypertension. The combined influence of these two factors had synergistic detrimental effects on cognitive functions.

Aging↗
PubMed2005

Learning and memory.

Learning and memory processes are thought to underlie a variety of human psychiatric disorders, including generalised anxiety disorder and post-traumatic stress disorder. Basic research performed in laboratory animals may help to elucidate the aetiology of the respective diseases. This chapter gives a short introduction into theoretical and practical aspects of animal experiments aimed at investigating acquisition, consolidation and extinction of aversive memories. It describes the behavioural paradigms most commonly used as well as neuroanatomical, cellular and molecular correlates of aversive memories. Finally, it discusses clinical implications of the results obtained in animal experiments in respect to the development of novel pharmacotherapeutic strategies for the treatment of human patients.

Animals↗
PubMed2005

Potential association of lead exposure during early development of mice with alteration of hippocampus nitric oxide levels and learning memory.

OBJECTIVE: Chronic lead (Pb) exposure during development is known to produce learning deficits. Nitric oxide participates in the synaptic mechanisms involved in certain forms of learning and memory. This study was designed to clarify whether Pb-induced impairment in learning and memory was associated with the changes of nitric oxide levels in mice brains. METHODS: Sixty Balb/c mice aged 10 days were chosen. A model of lead exposure was established by drinking 0.025%, 0.05%, 0.075% lead acetate, respectively for 8 weeks. The controls were orally given distilled water. The ability to learn and memorize was examined by open field test, T-water maze test. In parallel with the behavioral data, NO level of hippocampus tissue was detected by biochemical assay. RESULTS: Compared with control groups, (1) the weight of 0.075% group was significantly reduced (P<0.05); (2) The number of times in mice attaining the required standards in T-water maze test was lower in 0.075% group (P<0.01). No significant difference was found between experimental and control groups in open field test (P>0.05); (3) NO level of mouse hippocampus tissue was decreased in 0.075% group (P<0.01). CONCLUSIONS: The findings suggest that decreased hippocampus NO level may contribute to the Pb-induced deficits in learning and memory processes.

Animals↗
PubMed2000

Novel vs. well-learned memory for faces: a positron emission tomography study.

Previous work has suggested that familiarity/novelty of learned materials affects the circuitry involved in memory, primarily in the size of activations rather than the pattern of activation. Although this work has examined both recall and recognition, it has been limited to verbal material. In this study, we set out to determine if the same result applies to nonverbal memory. We used the same experimental design, but used faces as the memory task. Healthy volunteers thoroughly learned a set of 18 faces a week prior to the Positron Emission Tomography (PET) experiment (well-learned memory) and were asked to remember another set of 18 faces, to which they were exposed 1 min before the PET experiment (novel memory). During the PET session, their task was to recognize the faces learned a week before and the faces seen a minute before; the "remembered faces" were interspersed among entirely new (distractor) faces. We found that, unlike for verbal material, the retention interval and the familiarity level of the faces affected both the pattern and the size of activations. Comparing the novel and well-learned recognition tasks revealed that novel memory for faces is primarily a frontal-lobe task, while well-learned recognition memory for faces utilizes a more distributed neural circuit, including visual areas, which appear to serve as memory-storage sites.

Adult↗
PubMed2005

CAT 53: a protein phosphatase 1 nuclear targeting subunit encoded in the MHC Class I region strongly expressed in regions of the brain involved in memory, learning, and Alzheimer's disease.

We identified CAT 53 by cDNA hybridization selection as an expressed sequence tag (EST), located in the vicinity of HLA-C and designated as CAT (for HLA-C associated transcript) 53. CAT 53 encodes a protein described by others and commonly known as phosphatase 1 nuclear targeting subunit (PNUTS). PNUTS is a potent inhibitor of nuclear serine/threonine protein phosphatase 1 (PP1). We present the genomic organization of CAT 53, localize specific sites of mRNA transcription in thin sections of mouse brain by in-situ hybridization, and perform a structural analysis of the peptide domains. We also characterize the protein expression pattern for PNUTS by Western blotting and immunohistochemistry with PNUTS antibody in Alzheimer's disease (AD) brains and age-matched control brains. In-situ hybridization and immunohistochemistry analysis of human and mouse brain show high CAT 53 expression in the olfactory cortex, piriform cortex, and hippocampus. Very high expression of CAT 53 was found mainly in the hippocampus, frontal, and entorhinal cortex of control brains and in the neurofibrillary tangles of AD brain. In the hippocampus, CAT 53 is expressed in CA1 and CA3 cell layers and in the dentate gyrus. The hippocampus is known to play a fundamental role in learning and episodic memories and has been implicated in a number of neurological and psychiatric disorders, including AD, epilepsy, and schizophrenia. Our findings suggest that PNUTS, encoded by CAT 53 on 6p21.3, may have a role in the progression of AD.

Aged↗
PubMed2005

A memory learning framework for effective image retrieval.

Most current content-based image retrieval systems are still incapable of providing users with their desired results. The major difficulty lies in the gap between low-level image features and high-level image semantics. To address the problem, this study reports a framework for effective image retrieval by employing a novel idea of memory learning. It forms a knowledge memory model to store the semantic information by simply accumulating user-provided interactions. A learning strategy is then applied to predict the semantic relationships among images according to the memorized knowledge. Image queries are finally performed based on a seamless combination of low-level features and learned semantics. One important advantage of our framework is its ability to efficiently annotate images and also propagate the keyword annotation from the labeled images to unlabeled images. The presented algorithm has been integrated into a practical image retrieval system. Experiments on a collection of 10,000 general-purpose images demonstrate the effectiveness of the proposed framework.

Algorithms↗