[Spatial learning in two strains of Lurcher mice exposed to high frequency electromagnetic fields].
Explore the source record for details and available documents.
Animals↗
SEARCH · Search PubMed
Results for “Maze Learning”
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.
Differential effects of THC- or CBD-rich cannabis extracts on working memory in rats.
Cannabinoid receptors in the brain (CB(1)) take part in modulation of learning, and are particularly important for working and short-term memory. Here, we employed a delayed-matching-to-place (DMTP) task in the open-field water maze and examined the effects of cannabis plant extracts rich in either Delta(9)-tetrahydrocannabinol (Delta(9)-THC), or rich in cannabidiol (CBD), on spatial working and short-term memory formation in rats. Delta(9)-THC-rich extracts impaired performance in the memory trial (trial 2) of the DMTP task in a dose-dependent but delay-independent manner. Deficits appeared at doses of 2 or 5 mg/kg (i.p.) at both 30 s and 4 h delays and were similar in severity compared with synthetic Delta(9)-THC. Despite considerable amounts of Delta(9)-THC present, CBD-rich extracts had no effect on spatial working/short-term memory, even at doses of up to 50 mg/kg. When given concomitantly, CBD-rich extracts did not reverse memory deficits of the additional Delta(9)-THC-rich extract. CBD-rich extracts also did not alter Delta(9)-THC-rich extract-induced catalepsy as revealed by the bar test. It appears that spatial working/short-term memory is not sensitive to CBD-rich extracts and that potentiation and antagonism of Delta(9)-THC-induced spatial memory deficits is dependent on the ratio between CBD and Delta(9)-THC.
Animals↗
Effects of the non-pseudoautosomal region of the Y-chromosome on behavior in female offspring of two congenic strains of mice.
The learning behavior of female offspring of two strains of mice congenic for the Y-chromosome, BXSX/MpJ-Yaa and BXSB/MpJ-Yaa+, was examined. Significant differences were found in the Morris water maze and the Lashley III maze, demonstrating that the fathers' Y-chromosome can indirectly affect their daughters' behavior. Approximately half the mice had neocortical ectopias, and females from the two paternal groups reacted differently to the presence or absence of ectopias. Since females do not have a Y-chromosome, these effects must be through non-genetic mechanisms. Prenatal factors that could have played a role include possible differences in gonadal growth and the presence of different H-Y antigens. Postnatally, the sires and male siblings of the two strains may not have behaved the same toward the female offspring and/or the dams, creating differences in behavior. In summary, the behavior of female offspring of two groups of males, genetically the same except for their Y-chromosomes, was examined. Since females do not receive a Y-chromosome from their fathers, in theory their behavior should not differ. Significant differences were found, indicating that the Y-chromosome, through some indirect mechanism, can affect females of the next generation.
Animals↗
Effects of the uterine environment and neocortical ectopias upon behavior of BXSB-Yaa+ mice.
Between 40-60% of BXSB-Yaa+mice have neocortical ectopias, a genetically based brain anomaly. The presence of ectopias is known to affect several cognitive measures. A second way to affect cognition is by transferring embryos into foreign uteri. These variables were jointly investigated in three experiments. BXSB-Yaa+mouse embryos were transferred into same-strain uteri, or into uteri of hybrid mice. At birth, pups were cross-fostered to hybrid mothers or were reared by their birth mothers. When adult, the mice were given a series of behavioral tests with primary emphasis upon cognitive competence. Across all three studies, mice transferred into hybrid uteri were superior in the Morris maze and the Lashley III maze, and performed more effectively in shuttlebox avoidance learning. They were less effective in the simple water escape task, and the uterus groups did not differ in discrimination learning. Thus, development within a foreign uterus enhanced spatial learning and fear-based conditioning. Ectopic mice were superior to non-ectopics in learning the Morris maze, a finding consistent with prior research using the congenic BXSB-Yaa strain. There were Uterus x Ectopia interactions on a few measures, indicating that, under certain condition, whether the presence of ectopias is beneficial or detrimental is contingent upon the uterine environment within which the organism develops.
Animals↗
Assessment of spatial learning abilities of mice in a new circular maze.
In the present study, we tested the spatial learning behavior of four different mouse strains (129/Sv, BALB/c, C57BL and Swiss) in a newly developed circular maze. The maze was based on the circular Barnes maze, which was initially developed for rats. Since mice do not readily enter holes in floor, additional reinforcers (positive and negative) or pretraining procedures have been used to train the animals. Because these methods are not always desirable, we examined whether mice are more willing to enter escape holes (12), which were located in the rim of the apparatus. C57BL mice appeared to improve their performance on three different measures of spatial learning: latency to find escape hole, distance to escape hole and errors (visit to other holes). The other strains also improved their performance although this was only seen for one parameter (i.e. 129/Sv and BALB/c on latency, and Swiss on distance). When the animals were trained to find another location, it was found that only the performance of the C57BL mice was transiently impaired. The C57BL mice were also very efficient in improving their performance in a repeated acquisition paradigm (six trials per day on four successive days). Applying a probe trial procedure, a clear preference for the goal location was found. These findings indicate that these mice used a spatial search strategy. Although this circular maze can be used as an additional tool to assess spatial learning in (genetically modified) mice, it is noted that strain differences in spatial learning seem to be independent of task. Further, our data with different strains indicate that different measures of behavior should be evaluated to assess the spatial learning performance of mice.
Analysis of Variance↗
Functional and neurochemical profile of place learning after L-nitro-arginine in the rat.
Rats in which near-total inhibition of the nitric oxide synthesizing enzyme (NOS) had been obtained by a 5-day pretreatment during which two daily injections of L-nitro-arginine (50 mg/kg per injection) had been administered were subjected to five sessions of training on a place learning task (one session per day). NOS inhibition was associated with significantly impaired task acquisition but on the fifth training session normal task proficiency was achieved. Subsequent pharmacological and behavioral challenges established that dissimilar neural substrates mediated the task in NOS-inhibited and normal animals. In NOS-inhibited rats the neural substrate of task mediation depended less than normally on cholinergic mechanisms while potentially relying more on catecholaminergic mediation. In a separate experiment rats that had acquired the place learning task to asymptotic quality of performance were subjected to a L-nitro-arginine treatment similar to the pretreatment of the first experiment. Such a NOS inhibition did not impair subsequent task performance. It is concluded that nitric oxide participates in processes subserving acquisition rather than performance of at least some forms of place learning.
Amino Acid Oxidoreductases↗
Model systems for assessing cognitive function: implications for HIV-1 infection and drugs of abuse.
Memory deficits are common among drug abusers and in those with chronic neurodegenerative disorders. Currently, the mechanisms through which diverse neurophysiologic processes alter memory are not known. This review describes the current systems and rationale for studying memory formation, consolidation, and recall. Special attention is given to physiologic (hippocampal long-term potentiation) and behavioral animal models. The principles and methods described can be applied to studies of diverse clinical disorders.
AIDS Dementia Complex↗
AR-R 17779 improves social recognition in rats by activation of nicotinic alpha7 receptors.
RATIONALE: Nicotine and agonists at alpha(4)beta(2) and alpha(7) nicotinic acetylcholine receptors (nAChRs) improve learning and memory. The alpha(7)-nAChR subtype is of special interest, since it appears to play no role in the abuse liability of nicotine. OBJECTIVES AND METHODS: To further investigate the role of the alpha(7)-nAChR in learning and memory, the effects of the specific alpha(7)-nAChR agonist AR-R17779 on cognition were measured in the rat social recognition test (SRT) and the effect of the alpha(7)-nAChR antagonist methyllycaconitine (MLA) was studied. The SRT and a scopolamine-induced deficit version were validated with the acetylcholinesterase inhibitor metrifonate. Social memory was measured by the ability of an adult rat to recognize a juvenile rat after a delay. The difference in social interaction time (SIT) was measured between two encounters. The difference in SIT is expressed as percent reduction in social interaction time (%RSIT). RESULTS: Metrifonate (10 and 30 mg/kg PO) increased %RSIT in a behaviorally specific manner, employing a 24-h interval and reversed the scopolamine-induced deficit at a retention time of 15 min. Likewise, AR-R17779 increased %RSIT in unimpaired animals (1, 3, 10 and 30 mg/kg SC) employing a 24-h retention interval, and reversed the scopolamine-induced deficit (0.3 and 1 mg/kg SC) after a 15-min retention interval. The effects of AR-R17779 (1 mg/kg SC) in unimpaired animals were reversed by MLA (10 micro g ICV), which induced a decrease of %RSI at a 15-min retention interval when given alone. CONCLUSIONS: AR-R17779 increased social recognition memory by activation of alpha(7)-nAChRs, suggesting that alpha(7)-nAChR agonists possess cognitive-enhancing properties.
Aconitine↗
Spatial discrimination deficits by excitotoxic lesions in the Morris water escape task.
The effects of the cholinesterase inhibitors (ChEI) metrifonate and donepezil were assessed on spatial performance of rats with bilateral lesions of the entorhinal cortex (EC), which is thought to model early changes in the brains of patients suffering from Alzheimer's disease. In the present study, we found that spatial discrimination deficits in rats, induced by bilateral ibotenic acid (IBO) lesions of the EC region can partially be antagonised by treatment with the cholinesterase inhibitors metrifonate (30 mg kg(-1)) and donepezil (0.3 and 3 mg kg(-1)). Performance was improved in the spatial discrimination task compared with that of the EC-lesioned control group. It is concluded that the rat with bilateral EC lesions is a suitable deficit model for the assessment of effects of putative Alzheimer therapeutics.
Analysis of Variance↗
Diverse odor-conditioned memories require uniquely timed dorsal paired medial neuron output.
Amnesiac mutant flies have an olfactory memory defect. The amn gene encodes a homolog of vertebrate pituitary adenylate cyclase-activating peptide (PACAP), and it is strongly expressed in dorsal paired medial (DPM) neurons. DPM neurons ramify throughout the mushroom bodies in the adult fly brain, and they are required for stable memory. Here, we show that DPM neuron output is only required during the consolidation phase for middle-term odor memory and is dispensable during acquisition and recall. However, we found that DPM neuron output is required during acquisition of a benzaldehyde odor memory. We show that flies sense benzaldehyde by the classical olfactory and a noncanonical route. These results suggest that DPM neurons are required to consolidate memory and are differently involved in memory of a volatile that requires multisensory integration.
Analysis of Variance↗
Human place learning in a virtual Morris water task: some important constraints on the flexibility of place navigation.
We investigated human place learning in a computerized version of the Morris water task (VMWT) under comparable conditions to those employed by Sutherland et al. (Sutherland et al. Psychobiology, 1987;15:48-57) with rats. Participants viewed a computer-generated environment and were trained to locate a hidden goal in one half of a circular pool (region 1). The opportunity to navigate in and view cues from region 2 was systematically varied during training. Participants were then started from region 2 to assess transfer. Accurate transfer performance was dependent upon prior experience viewing distal cues from region 2 while on a trajectory to the goal, a finding we interpret as inconsistent with the automatic formation and modification of a cognitive map (O'Keefe J, Nadel L. The Hippocampus as a cognitive map. Oxford, UK: Clarendon Press, 1978). Additionally, the transfer data reported here closely match the data obtained by Sutherland et al. with rats suggesting some generality in the principles involved in place learning.
Acoustic Stimulation↗
Inhibitory avoidance impairments induced by intra-amygdala propranolol are reversed by glutamate but not glucose.
Both systemic and central injections of glucose can enhance memory. For example, glucose reverses impairments on inhibitory avoidance resulting from intra-amygdala injections of morphine. The present experiment investigated the ability of glucose to reverse memory impairments resulting from intra-amygdala injections of propranolol, a beta-noradrenergic antagonist. Pretraining administration of 10 microg propranolol significantly reduced inhibitory avoidance retention latencies but had no effect on performance in a spontaneous alternation task. Coadministration of glucose into the amygdala at 3 doses (1.5, 3.0, and 6.0 microg) did not reverse the propranolol-induced inhibitory avoidance deficits. However, coadministration of 2.5 microg of glutamate with the propranolol did reverse these deficits. The ability of glucose to reverse impairments following intra-amygdala injections of morphine but not propranolol may reflect the neurotransmitter system or systems through which glucose exerts its effects.
Adrenergic beta-Antagonists↗
Effects of repeated exposure of rats to JP-5 or JP-8 jet fuel vapor on neurobehavioral capacity and neurotransmitter levels.
The U.S. Naval Service is anticipating transition from the nearly exclusive use of JP-5 jet fuel to predominant use of JP-8, consistent with the primary utilization by the U.S. Army, U.S. Air Force, and the militaries of most NATO countries. To compare the relative risk of repeated exposure to JP-5 versus JP-8 vapor, groups of 32 male Sprague-Dawley rats each were exposed for 6 h/d, 5 d/wk for 6 wk (180 h) to JP-8 jet fuel vapor (1,000 +/- 10% mg/m3), IP-5 vapor (1,200 +/- 10% mg/m3), or room air control conditions. Following a 65-d rest period, rats completed 10 tests selected from the Neurobehavioral Toxicity Assessment Battery (NTAB) to evaluate changes in performance capacity. Repeated exposure to JP-5 resulted in significant effects on only one test, forelimb grip strength (FGS), while exposure to JP-8 vapor resulted in a significant difference versus controls on appetitive reinforcer approach sensitization (ARAS). Rats were further evaluated for concentrations of major neurotransmitters and metabolites in five brain regions and in the blood serum. Levels of dopamine, the dopamine metabolite dihydroxyphenylacetic acid (DOPAC), and the serotonin metabolite homovanillic acid (HVA) were significantly modulated in various brain regions, as measured 85+ d postexposure. Similarly, serum levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) were differentially modulated following JP-8 or JP-5 exposure. Results are compared to previously published research evaluating the neurotoxicity of repeated exposure to other hydrocarbon fuels and solvents.
3,4-Dihydroxyphenylacetic Acid↗
Dynamics of olfactory learning-induced up-regulation of L1 in the piriform cortex and hippocampus.
L1 is a cell adhesion molecule implicated in the formation of neural circuits and synaptic plasticity. We have examined the sequence and time-frame in which modifications in the synaptic expression of L1 occur in the piriform cortex and hippocampus in the course of rule learning of an olfactory discrimination task. Rats were trained to choose the correct odour in a pair to be rewarded with drinking water. Such training requires 6-8 days on average before rats reach maximal performance. We observed a learning-induced L1 up-regulation that occurred at an early training stage in the piriform cortex but only after rule-learning establishment in the hippocampus. We suggest that the dynamics of L1 up-regulation may reflect the functional role of these brain regions in olfactory rule learning.
Analysis of Variance↗
Interaction with sigma(1) protein, but not N-methyl-D-aspartate receptor, is involved in the pharmacological activity of donepezil.
In the present study, we examined the interaction of (+/-)-2,3-dihydro-5,6-dimethoxy-2-[[1-(phenylmethyl)-4-piperidinyl]-methyl]-1H-inden-1-one hydrochloride (donepezil), a potent cholinesterase inhibitor, with two additional therapeutically relevant targets, N-methyl-d-aspartate (NMDA) and sigma(1) receptors. Donepezil blocked the responses of recombinant NMDA receptors expressed in Xenopus oocytes. The blockade was voltage-dependent, suggesting a channel blocker mechanism of action, and was not competitive at either the l-glutamate or glycine binding sites. The low potency of donepezil (IC(50) = 0.7-3 mM) suggests that NMDA receptor blockade does not contribute to the therapeutic actions of donepezil. Of potential therapeutic relevance, donepezil binds to the sigma(1) receptor with high affinity (K(i) = 14.6 nM) in an in vitro preparation (Neurosci Lett 260:5-8, 1999). Thus, we sought to determine whether an interaction with the sigma(1) receptor may occur in vivo under physiologically relevant conditions by evaluating the sigma(1) receptor dependence effects of donepezil in behavioral tasks. Donepezil showed antidepressant-like activity in the mouse-forced swimming test as did the sigma(1) receptor agonist igmesine. This effect was not displayed by the other cholinesterase inhibitors, rivastigmine and tacrine. The donepezil and igmesine effects were blocked by preadministration of the sigma(1) receptor antagonist N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino) ethylamine (BD1047) and an in vivo antisense probe treatment. The memory-enhancing effect of donepezil was also investigated. All cholinesterase inhibitors attenuated dizocilpine-induced learning impairments. However, only the donepezil and igmesine effects were blocked by BD1047 or the antisense treatment. Therefore, donepezil behaved as an effective sigma(1) receptor agonist on these behavioral responses, and an interaction of the drug with the sigma(1) receptor must be considered in its pharmacological actions.
Animals↗
[The effects of rat selection and reproduction on learning ability in the offspring].
We studied the effect of selective reproduction on rats purchased from a breeder, so as to detect learning impairments in their offspring. The parent rats selected for mating were categorized as bright or dull in terms of learning ability on the basis of a learning test in a water maze or passive avoidance response (PAR). Offspring were tested in the same way as the selected rats, with their responses being compared for each generation. 1. The matings, consisting of bright X bright, bright X dull, dull X bright, dull X dull, resulted in a significant increase in the number of dull offspring of dull X dull from parents selected by water maze or PAR learning test. 2. Bright or dull mothers selected by PAR learning were treated with chlorpromazine 6 mg/kg (2 times/day/s.c.) on the 13th day of gestation. Afterwards, a slight increase in dull offspring of dull parents was seen. 3. These results indicate that in order to evaluate the learning ability of F1 in a reproductive test, it is first necessary to check the reaction of the parents, purchased F0, and to classify them as bright or dull.
Animals↗
Effects of sodium barbitone on learning and memory-storage of an appetitive and an aversive task.
In order to test the effects of sodium barbitone on the acquisition and retention of an appetitively and an aversively reinforced behavior, mice were trained in a spatial discrimination Y-maze task. Learning was observed in both situations, with acquisition unimpaired by the drug. Sodium barbitone did, however, affect retention of both tasks in all groups treated with the drug before training. Results are discussed in light of the various modes of action of this drug, i.e., as an inhibitor of protein synthesis, as a blocker of catecholamine biosynthesis, with regard to its effects on paradoxical sleep and on gamma-amino-butyric acid (GABA).
Animals↗
Learning impairment in chronic epileptic rats following pilocarpine-induced status epilepticus.
Male Wistar rats were subjected to pilocarpine-induced status epilepticus and allowed to recover. After reaching the chronic state with spontaneous seizures they were tested in an 8-arm radial maze. During learning trials, epileptic rats made significantly more errors than controls. Even in the last trials epileptic rats did not improve their performance, indicating severe learning disability. These results suggest that spontaneous seizures after pilocarpine-induced status epilepticus are a useful model for studying the learning and memory impairment detected in some cases of symptomatic epilepsy.
Animals↗