Memory Retention Test Research Articles

Exposure to Methamphetamine During First and Second Half of Prenatal Period and Its Consequences on Cognition After Long-Term Application in Adulthood

It is known that psychostimulants including methamphetamine (MA) have neurotoxic effect, especially, if they are targeting CNS during its critical periods of development. The present study was aimed on evaluation of cognitive changes following scheduled prenatal MA exposure in combination with long-term exposure in adulthood of male rats. Two periods of gestation were targeted: 1(st) half - the embryonic day (ED) 1-11 and 2(nd) half - ED 12-22. Rat mothers received subcutaneously a daily injection of MA (5 mg/kg) or saline (SAL, 1 ml/kg) throughout scheduled periods. Male offspring were tested for cognitive changes in the Morris Water Maze (MWM) in adulthood. Each day of the experiment animals received an injection of MA (1 mg/kg) or SAL (1 ml/kg) during 12 days. Our results demonstrated that in the group of animals exposed to the drug during ED 1-11, neither prenatal MA exposure, nor adult MA treatment changed the performance in the MWM test. Only the velocity was increased in group with long-term MA treatment (SAL/MA and MA/MA). In the group of animals exposed to the drug during ED 12-22, rats exposed to MA prenatally and also in adulthood (MA/MA) swam faster but learned the position of the platform slower in the Place Navigation Test than animals exposed to SAL in adulthood (MA/SAL). In the Probe Test, MA/SAL had decreased velocity and swam shorter distance than MA/MA or SAL/SAL rats suggesting increased floating of these animals. In the Memory Retention Test, SAL/MA rats swam shorter distance than SAL/SAL or MA/MA animals suggesting changes in used strategies in memory recall. As conclusion, our results suggest differences in the effect of combination of prenatal and adult exposure to MA. These effects further depend on the stage of CNS development and schedule of MA exposure affecting intrauterine development in male rats.

Prenatal methamphetamine exposure induces long-lasting alterations in memory and development of NMDA receptors in the hippocampus.

Since close relationship was shown between drug addiction and memory formation, the aim of the present study was to investigate the effects of interaction between prenatal methamphetamine (MA) exposure and MA treatment in adulthood on spatial and non-spatial memory and on the structure of the N-methyl-D-aspartate (NMDA) receptors in the hippocampus. Adult male rats prenatally exposed to MA (5 mg/kg) or saline were tested in adulthood. Non-spatial memory was examined in the Object Recognition Test (ORT) and spatial memory in the Object Location Test (OLT) and in the Memory Retention Test (MRT) conducted in the Morris Water Maze (MWM), respectively. Based on the type of the memory test animals were injected either acutely (ORT, OLT) or long-term (MWM) with MA (1 mg/kg). After each testing, animals were sacrificed and brains were removed. The hippocampus was then examined in Western Blot analysis for occurrence of different NMDA receptors' subtypes. Our results demonstrated that prenatal MA exposure affects the development of the NMDA receptors in the hippocampus that might correspond with improvement of spatial memory tested in adulthood in the MWM. On the other hand, the effect of prenatal MA exposure on non-spatial memory examined in the ORT was the opposite. In addition, we showed that the effect of MA administration in adulthood on NMDA receptors is influenced by prenatal MA exposure, which seems to correlate with the spatial memory examined in the OLT.

Effects of acute stress on learning and memory processes of malnourished rats

The aim of the study was to investigate the effects of acute stress on the processes of learning and memory in malnourished rats tested in the Morris water maze. The animals were divided into eight groups according to nutritional status (malnourished or well nourished) and stress (stressed or unstressed). In Experiment I the animals were subjected to immobilization stress procedure before the learning session and in Experiment II after the learning sessions. The test consisted of two daily sessions, and a memory test after four weeks. There was loss of learning and memory in malnourished rats. In Experiment I the malnourished group was positively affected by acute stress, with significant improvement of performance. No effects of stress on the animals' performance in Experiment II were observed. In the memory test, the malnourished rats showed deficits in consolidation and recall, regardless of the occurrence of stress. The stress imposed 24 hours before the learning task improved performance of malnourished animals with a protective effect of stress. However there was no improvement in the processes of retention or recall from memory (previously learned information) assessed four weeks later, during the memory retention test.

Effect of Methylphenidate on Retention and Retrieval of Passive Avoidance Memory in Young and Aged Mice

Background: Several studies showed that dopamine and norepinephrine improve retention and retrieval of memory. Methylphenidate is an enhancer of dopamine and norepinephrine in brain. Objectives: In the present study, the effect of methylphenidate was evaluated on retention and retrieval of memory in young and aged mice using passive avoidance apparatus. Materials and Methods: Animals were divided into groups (n = 8) as follows: test groups received electric shock plus methylphenidate (2.5, 5 and 10mg kg-1, i. P.), control group received electric shock plus normal saline and blank group received only electric shock. In all groups, step-down latency for both retention and retrieval test of memory was measured. Methylphenidate was administered immediately after receiving electric shock in the retention test, but methylphenidate was administered 23.5 hours after receiving electric shock in the retrieval test. Results: The mean of step-down latency on day 4 was significantly higher compared to day 2 (P < 0.05) in all young and aged groups of mice. The best response was attained with 5 mg/kg of methylphenidate. In memory retention test, the mean of step-down latency in young groups that received 2.5 and 5 mg/kg methylphenidate was significantly longer(P < 0.05) than aged groups. However, this difference was not significant in memory retrieval test. Conclusions: Methylphenidate may improve memory retention and retrieval.

P.1.g.008 Psychopharmacological pattern in heart transplantation candidates

0.1mg/kg was observed decreased number of escapes on 1st, 2nd and 3rd days compared to the same day controls. In the group treated with eletriptan 0.5mg/kg significant increase of the number of escapes was observed only on 1st day, compared to the same day control. On 2nd and 3rd days of learning session was observed significant decrease in the number of escapes, compared to the same day control. The control group significantly increased the number of intertrail crossings on 2nd and 3rd days of learning session, compared to the 1st day. Rats from the group treated with eletriptan 0.1mg/kg increased significantly the number of intertrail crossings on 1st and 5th days of learning session and on memory retention test, compared to the same day controls. Group treated with eletriptan 0.5mg/kg increased the number of intertrail crossings on 1st and 5th days of learning session, compared to the same controls. Conclusion: Our data permitt the suggestion, that 5-HT agonist eletriptan at a low dose improve the learning and memory processes. Having in mind its antimigraine effects it may be speculated that eletriptan shall improve the memory functioning as well.

Effects of corticosterone on contextual fear consolidation in intact and ovariectomized female rats

Previous studies have shown that post-training administration of glucocorticoids enhances memory consolidation in male rats, but theirs effects on female rats are not known. Thus, this study was conducted to examine the effects of corticosterone (CORT) on contextual fear memory consolidation in intact and ovariectomized (OVX) female rats. In Experiment 1, post-training administration of CORT (0.3, 3, and 10mg/kg) to OVX female rats impaired memory consolidation at a 0.3mg dose of CORT. In Experiment 2, post-training injection of CORT (0.3mg/kg) to female rats in proestrus stage (when the levels of estrogens are highest) enhances and in the estrus stage (when the levels of estrogens are lowest) impaired memory retention. In Experiment 3, OVX female rats injected with CORT (0.3mg/kg) and one of the three doses of 17β-estradiol (1, 10 or 100μg/kg) following training. 48-h memory retention test indicated that CORT enhanced memory retention in OVX female rats that received concurrent injection of 10 or 100μg doses of 17β-estradiol. These findings indicate that cognitive effects of CORT in female rats can be modulated with the plasma levels of estrogens: when the levels of estrogens are low, corticosterone has a negative effect, while when the levels of estrogens are high; the corticosterone has a positive enhancing effect.

Participation of muscarinic receptors in memory consolidation in passive avoidance learning.

It is well-known that the cholinergic system and the muscarinic cholinergic receptors are associated with cognitive functions. Here we examined whether a non-selective muscarinic receptor antagonist scopolamine affects learning performance and/or synaptic plasticity during the memory consolidation period. Adult male Wistar rats (250-300 g) were injected with scopolamine (2 mg/kg) or saline immediately after training in a "passive avoidance" task. Memory retention test was conducted 24 h after training. The changes in the latency of the first entry into a dark compartment of a test chamber was chosen as a criterion of learning. The efficacy of synaptic transmission was estimated by the changes in the basal level of focal potentials (fEPSP amplitude and slope ratio) before training (baseline), 90 min after the training (consolidation period), and 24 hour after the training (retention period). We found that foot-shock presentation by itself had no effect on fEPSP within the first 90 min after training, but in 24 hour fEPSPs were decreased. In untrained rats administration of scopolamine had no effect on the fEPSP amplitude within the first 90 min after the injection, but in 24 h we observed an increase in the fEPSP amplitude. In trained animals, scopolamine decreased the fEPSP amplitude in the hippocampal CA1 area during first 1.5 h after the injection. However, the drug had no effect on the memory retention in the passive avoidance task. Taken together our data suggest that scopolamine modifies the synaptic placticity of the hippocampal network but does not induce significant changes in the retention of the passive avoidance skill.

P.2.014 Study of the effects of aripiprazole and olanzapine on learning and memory in naive rats and rats with apomorphine-induced behavior

Purpose: Aripiprazole is an atypical antipsychotic alternative for antipsychotic drugs that adversely affect cognitive processes [1]. The atypical antipsychotic olanzapine acts as a dopamine, serotonin and muscarinic antagonist, and its effect on these neurotransmitters could result in memory impairment in working memory tasks [2]. Apomorphine induces conditioning by stimulation of dopamine receptors [3]. Our aim was to assess the impact of aripiprazole and olanzapine on behavioral functions of rats, with particular emphasis on memory effects after multiple dosing. Methods: Two experiments were carried out using the active avoidance test. Experiment 1 (naive rats) comprised 6 groups of 8 male Wistar rats each, treated intraperitoneally (i.p.) with: (1) saline 0.1ml/100 g (control group); (2,3) aripiprazole 1mg/kg and 3mg/kg, respectively; (4,5,6) olanzapine 0.5mg/kg, 1mg/kg and 2mg/kg, respectively. Experiment 2 (apomorphine-challenged rats) comprised 4 groups of 8 male Wistar rats each, treated intraperitoneally (i.p.) with: (1) saline 0.1ml/100 g (control group); (2) apomorphine 0.5mg/kg; (3) apomorphine 0.5mg/kg plus aripiprazole 1mg/kg; (4) apomorphine 0.5mg/kg plus olanzapine 1mg/kg. Rats were trained in an automatic reflex conditioner (shuttle box) with 5 learning sessions on days 1−5 and a memory retention test on day 12. The following parameters were recorded: number of avoidances, number of escapes from foot shock and number of inter-trial crossings. Statistical evaluation was performed using ANOVA. Results: Of the naive rats, the control group significantly increased the number of avoidances both in learning sessions and in the memory retention test, compared to day 1. Rats treated with aripiprazole had lower numbers of avoidances than controls in all learning sessions and in the memory retention tests. Rats treated with olanzapine had lower numbers of avoidances than controls in the learning sessions on days 4 and 5 and in the memory retention test. In all of the naive rats, neither the number of escapes nor the number of inter-trial crossings changed during the learning sessions and the memory test. Of the rats challenged with apomorphine, those treated only with apomorphine had increased numbers of avoidances in the learning sessions and in memory retention test (p< 0.05). Rats treated with apomorphine plus aripiprazole had lower numbers of avoidances than apomorphine-only rats in the learning sessions on days 3, 4 and 5 and in the memory retention test (p< 0.05). Rats treated with apomorphine plus olanzapine had similar numbers of avoidances as apomorphine-only rats in the learning sessions, but lower numbers in the memory retention test (p< 0.05). The numbers of escapes and intertrial crossings showed a similar tendency. Conclusion: In these experiments, the antipsychotic drugs aripiprazole and olanzapine impaired learning and memory of apomorphine-naive rats in the active avoidance test. In apomorphine-challenged rats, aripiprazole antagonized the effects of apomorphine on both learning and memory, but olanzapine affected memory only. This suggests that aripiprazole and olanzapine modulate dopamine neurotransmission in different ways.

Blockage of the Upregulation of Voltage-Gated Sodium Channel Nav1.3 Improves Outcomes after Experimental Traumatic Brain Injury

Excessive active voltage-gated sodium channels are responsible for the cellular abnormalities associated with secondary brain injury following traumatic brain injury (TBI). We previously presented evidence that significant upregulation of Nav1.3 expression occurs in the rat cortex at 2 h and 12 h post-TBI and is correlated with TBI severity. In our current study, we tested the hypothesis that blocking upregulation of Nav1.3 expression in vivo in the acute stage post-TBI attenuates the secondary brain injury associated with TBI. We administered either antisense oligodeoxynucleotides (ODN) targeting Nav1.3 or artificial cerebrospinal fluid (aCSF) at 2 h, 4 h, 6 h, and 8 h following TBI. Control sham animals received aCSF administration at the same time points. At 12 h post-TBI, Nav1.3 messenger ribonucleic acid (mRNA) levels in bilateral hippocampi of the aCSF group were significantly elevated, compared with the sham and ODN groups (p<0.01). However, the Nav1.3 mRNA levels in the uninjured contralateral hippocampus of the ODN group were significantly lowered, compared with the sham group (p<0.01). Treatment with antisense ODN significantly decreased the number of degenerating neurons in the ipsilateral hippocampal CA3 and hilar region (p<0.01). A set of left-to-right ratio value analyzed by magnetic resonance imaging T2 image on one day, three days, and seven days post-TBI showed marked edema in the ipsilateral hemisphere of the aCSF group, compared with that of the ODN group (p<0.05). The Morris water maze memory retention test showed that both the aCSF and ODN groups took longer to find a hidden platform, compared with the sham group (p<0.01). However, latency in the aCSF group was significantly higher than in the ODN group (p<0.05). Our in vivo Nav1.3 inhibition studies suggest that therapeutic strategies to block upregulation of Nav1.3 expression in the brain may improve outcomes following TBI.

β-Asarone이 Lipopolysaccharide에 의한 생쥐 해마의 염증성 사이토카인 발현과 학습 및 기억 장애에 미치는 영향

Objectives : <TEX>${\beta}$</TEX>-Asarone (BAS) is an active ingredient in Acori Rhizoma. This study investigated anti-neuroinflammatory and memory ameliorating effects of BAS in systemic lipopolysaccharide (LPS)-treated C57BL/6 mice. Methods : BAS was administered orally at doses of 7.5, 15, and 30 mg/kg for 3 days prior to LPS (3 mg/kg, intraperitoneal) injection. Pro-inflammatory cytokine mRNA, including tumor necrosis factor-<TEX>${\alpha}$</TEX> (TNF-ㅍ), interleukin (IL)-<TEX>$1{\beta}$</TEX> and IL-6, was measured in hippocampus tissue using real-time polymerase chain reaction at 4 h after the LPS injection. An ameliorating effect of 30 mg/kg BAS on learning and memory impairment in the LPS-treated mice was verified using the Morris water maze test. Results : BAS significantly attenuated up-regulation of TNF-<TEX>${\alpha}$</TEX>, IL-<TEX>$1{\beta}$</TEX>, and IL-6 mRNA in hippocampus tissue of the LPS-treated mice. In acquisition training test, BAS improved learning performance of the LPS-treated mice with a significant decrease of escape latency to the platform. In memory retention test, BAS also ameliorated memory impairment of the LPS-treated mice with a significant increase of swimming time in zones neighboring to the platform, number of target heading, and memory score. Conclusion : The results suggest that inhibition of pro-inflammatory cytokines and neuroinflammation in the hippocampus by BAS could be one of the mechanisms for BAS-mediated ameliorating effect on learning and memory impairment in LPS-treated mice.

The effects of Zibu Piyin Recipe components on scopolamine-induced learning and memory impairment in the mouse

Ethnopharmacological relevanceThe Zibu Piyin Recipe (ZBPYR) is derived from Zicheng Decoction, a traditional Chinese medicine formula recorded in the book of Bujuji, written by Wu Cheng in the Qing dynasty and used for clinical treatment of amnesia. Our aim was to study the effects of Zibu Piyin Recipe (ZBPYR) fractions on scopolamine-induced learning and memory impairment in the mouse. Materials and methodsCrude extracts were prepared using various solvents, and individual fractions produced following D101 macroporous resin column chromatography. The passive avoidance task, step down test and Morris water maze test were then performed in mice for the evaluation of learning and memory alterations. The effective fractions were then analyzed using GC–MS and polysaccharide measurement methods, respectively. ResultsThe treatment group latency for the alcohol precipitation from water part (EP) and 95% ethanol part (95%E) following D101 macroporous resin column chromatography was significantly prolonged when compared to that of the scopolamine treated groups for both the passive avoidance task and step down test. In the Morris water maze tests, treatment with EP and 95%E resulted in a significantly shorter escape latency time (from the fourth day and the second day) and swimming distance (on the third day and from the third day) in scopolamine-induced mice. In the memory retention test, treatment with EP and 95%E dramatically shortened the latency to cross platform location and increased the numbers of platform location crosses in the scopolamine-induced mice. The polysaccharide content in EP was determined to be 69.79%. The 95%E was found to mainly contain asarone, α-cadinol, isocalamendiol, 2,4,7,14-tetramethyl-4-vinyl-tricyclo[5.4.3.0(1,8)]tetradecan-6-ol, 3-isopropyl-6,7-dimethyltricyclo[4.4.0.0(2,8)]decane-9,10-diol, 2-methyl-9-(prop-1- -en-3-ol-2-yl)-bicyclo[4.4.0]dec-2-ene-4-ol, diepicedrene-1-oxide, 7-methoxy-6-(3- -methyl-2-oxobutyl)-2H-1-benzopyran-2-one and diisooctyl phthalate when assessed using GC–MS analysis. ConclusionThese findings suggest that the polysaccharide and volatile oil present in ZBPYR exhibit ameliorating effects on scopolamine-induced memory dysfunction.

Effects of Long-Term Treatment with Atorvastatin and Rosuaastatin on Active Avoidance Test in Intact Rats

Summary Statins are widely used for treatment of hyperlipidemia. They have been shown to possess pleiotropic effects apart from their lipid-lowering activity - anti-inflammatory, immunomodulatory, and neuroprotective. Most studies suggest that statins can protect the brain against damage but it is not clear whether they improve cognitive function in patients without neuropathy. The aim of the present study was to investigate the effect of 3-month treatment with atorvastatin and rosuvastatin on learning and memory processes in rats without brain damage. Wistar rats were treated orally for 90 days with atorvastatin and rosuvastatin at a dose of 10 mg/kg b. w. in parallel with the vehicle-treated group. After that period, learning ability and memory retention was evaluated using an active avoidance test - automatic reflex conditioner (shuttle box). The learning session was carried out on 5 consecutive days. Memory retention test was performed on day 12. The following behavioral reactions were investigated: conditioned responses (avoidance), unconditioned responses (escapes), and intertrial crossings. We found increased number of conditioned responses in groups, treated with atorvastatin 10 mg/kg b.w., and with rosuvastatin 10 mg/kg b.w. during the learning session and on the memory retention test, as compared to the same-day control group. The atorvastatin-treated group showed an increased number of unconditioned responses on days 1 and 2, as compared to the control group. In the group treated with Rosuvastatin there was an increased number of escapes on days 1,2 and 4, as compared to the vehicle-treated group. Atorvastatin and rosuvastatin at a dose of 10 mg/kg b.w. improved processes of learning and memory retention after the 3-month treatment.

Comparison of learning ability and memory retention in altricial (Bengalese finch,Lonchura striata var. domestica) and precocial (blue-breasted quail,Coturnix chinensis) birds using a color discrimination task

The present study sought to assess the potential application of avian models with different developmental modes to studies on cognition and neuroscience. Six altricial Bengalese finches (Lonchura striata var. domestica), and eight precocial blue-breasted quails (Coturnix chinensis) were presented with color discrimination tasks to compare their respective faculties for learning and memory retention within the context of the two developmental modes. Tasks consisted of presenting birds with discriminative cues in the form of colored feeder lids, and birds were considered to have learned a task when 80% of their attempts at selecting the correctly colored lid in two consecutive blocks of 10 trials were successful. All of the finches successfully performed the required experimental tasks, whereas only half of the quails were able to execute the same tasks. In the learning test, finches required significantly fewer trials than quails to learn the task (finches: 13.5 ± 9.14 trials, quails: 45.8 ± 4.35 trials, P < 0.05), with finches scoring significantly more correct responses than quails (finches: 98.3 ± 4.08%, quails: 85.0 ± 5.77% at the peak of the learning curve). In the memory retention tests, which were conducted 45 days after the learning test, finches retained the ability to discriminate between colors correctly (95.0 ± 4.47%), whereas quails did not retain any memory of the experimental procedure and so could not be tested. These results suggested that altricial and precocial birds both possess the faculty for learning and retaining discrimination-type tasks, but that altricial birds perform better than precocial birds in both faculties. The present findings imply that developmental mode is an important consideration for assessing the suitability of bird species for particular experiments.

No Trade-Off between Learning Speed and Associative Flexibility in Bumblebees: A Reversal Learning Test with Multiple Colonies

Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris) were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals that were fast to learn yellow as a predictor of reward were also quick to reverse this association. Furthermore, overnight memory retention tests suggest that faster learning individuals are also better at retaining previously learned information. There is also an effect of relatedness: colonies whose workers were fast to learn the association between yellow and reward also reversed this association rapidly. These results are inconsistent with a trade-off between learning speed and the reversal of a previously made association. On the contrary, they suggest that differences in learning performance and cognitive (behavioural) flexibility could reflect more general differences in colony learning ability. Hence, this study provides additional evidence to support the idea that rapid learning and behavioural flexibility have adaptive value.

High-throughput olfactory conditioning and memory retention test show variation in Nasonia parasitic wasps.

Most of our knowledge on learning and memory formation results from extensive studies on a small number of animal species. Although features and cellular pathways of learning and memory are highly similar in this diverse group of species, there are also subtle differences. Closely related species of parasitic wasps display substantial variation in memory dynamics and can be instrumental to understanding both the adaptive benefit of and mechanisms underlying this variation. Parasitic wasps of the genus Nasonia offer excellent opportunities for multidisciplinary research on this topic. Genetic and genomic resources available for Nasonia are unrivaled among parasitic wasps, providing tools for genetic dissection of mechanisms that cause differences in learning. This study presents a robust, high-throughput method for olfactory conditioning of Nasonia using a host encounter as reward. A T-maze olfactometer facilitates high-throughput memory retention testing and employs standardized odors of equal detectability, as quantified by electroantennogram recordings. Using this setup, differences in memory retention between Nasonia species were shown. In both Nasonia vitripennis and Nasonia longicornis, memory was observed up to at least 5 days after a single conditioning trial, whereas Nasonia giraulti lost its memory after 2 days. This difference in learning may be an adaptation to species-specific differences in ecological factors, for example, host preference. The high-throughput methods for conditioning and memory retention testing are essential tools to study both ultimate and proximate factors that cause variation in learning and memory formation in Nasonia and other parasitic wasp species.

Mice Lacking the β4 Subunit of the Nicotinic Acetylcholine Receptor Show Memory Deficits, Altered Anxiety- and Depression-Like Behavior, and Diminished Nicotine-Induced Analgesia

The role of β4-containing nicotinic acetylcholine receptors (nAChRs) in cognition, anxiety, depression, and analgesia in the absence of nicotine is unclear. Wild-type (β4(+/+)) and knockout (β4(-/-)) mice for the nAChR β4 subunit were tested in behavioral tests assessing cognitive function, affective behaviors, and nociception. There were no learning and memory deficits in β4(-/-) mice compared with β4(+/+) mice during the acquisition of the Barnes maze, contextual fear conditioning, and Y maze tasks. In the Barnes maze memory retention test, male β4(-/-) mice showed reduced use of the spatial search strategy, indicating small spatial memory deficits compared with β4(+/+) mice. In the cue-induced fear conditioning memory retention test, β4(-/-) mice exhibited reduced freezing time compared with β4(+/+) mice. Compared with β4(+/+) mice, β4(-/-) mice exhibited decreased anxiety-like behavior in the light-dark box. Depression-like behavior in β4(-/-) mice was decreased in the tail suspension test and increased in the forced swim test compared with β4(+/+) mice. β4(-/-) mice did not differ from β4(+/+) mice in basal nociception but were less sensitive to the antinociceptive effect of nicotine in 2 tests of acute thermal pain. Lack of β4-containing nAChRs resulted in small deficits in hippocampus- and amygdala-dependent memory retention functions. β4-containing nAChRs are involved in anxiety- and depression-like behaviors and contribute to the analgesic effects of nicotine.

Neuronal activity during sleep and memory formation in the Honey bee

Event Abstract Back to Event Neuronal activity during sleep and memory formation in the Honey bee Florencia Campetella1, 2*, Ina Klinke1, Saikat Ray1, Martin P. Nawrot2, 3 and Randolf Menzel1, 3 1 Free University Berlin, Neurobiology, Germany 2 Free University Berlin, Neuroinformatics, Germany 3 Bernstein Center for Computational Neuroscience Berlin, Germany Human beings spend almost one third of their life sleeping, and the consequences of sleep deprivation have been widely reported. Despite the increasing insight into the mechanisms of sleep generation, the function of sleep still remains unclear. Several hypothesis have been proposed, one of which claims that sleep periods are favorable for brain plasticity and for learning and memory (1). In this framework, sleep would be involved in the processing of the memory traces that would then be incorporated into long-term memory. At the behavioral level, it has been reported that the honey bee Apis mellifera displays distinct sleep phases which can be monitored by tracking the bee's antennal movements, and that these sleep phases are associated with memory consolidation (2). But so far there is no evidence of the implications of the neuronal activity during sleep in memory formation. In this work, long term extracellular activity of multiple feedback neurons of the protocerebral-calycal tract (PCT) was recorded during a combined visual and olfactory learning paradigm, and during sleep phases as well. PCT neurons respond to a variety of sensory modalities (3) and are a potential candidate for multi-sensory learning and memory formation in the bee brain. By recording the activity of these neurons we were able to monitor the overall changes in multi-unit activity of PCT neurons during the sleep and awake phases, and to correlate the single unit activity pattern during training and testing sessions with the pattern observed during sleep for these units. Our goal is to relate neural activity during the sleep phases with the animal's performance during memory retention tests. (1) Maquet P (2001) The Role of Sleep in Learning and Memory. Science 294, 1048. (2) Hussaini A, Bogusch L, Landgraf T and Menzel R (2009) Sleep deprivation affects extinction but not acquisition memory in honeybees, Learn Mem. 2009 Oct 28;16(11):698-705. (3) Gronenberg W (1986) Physiological and anatomical properties of optical input-fibers to the mushroom body in the bee brain. J Insect Physiol 32:695-704. Keywords: electrophysiolgy, Memory, mushroom body, Sleep Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Learning, plasticity, memory Citation: Campetella F, Klinke I, Ray S, Nawrot MP and Menzel R (2012). Neuronal activity during sleep and memory formation in the Honey bee. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00151 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 11 May 2012; Published Online: 12 Sep 2012. * Correspondence: Miss. Florencia Campetella, Free University Berlin, Neurobiology, Berlin, Germany, fcampetella@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Florencia Campetella Ina Klinke Saikat Ray Martin P Nawrot Randolf Menzel Google Florencia Campetella Ina Klinke Saikat Ray Martin P Nawrot Randolf Menzel Google Scholar Florencia Campetella Ina Klinke Saikat Ray Martin P Nawrot Randolf Menzel PubMed Florencia Campetella Ina Klinke Saikat Ray Martin P Nawrot Randolf Menzel Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Involvement of the ventral tegmental area in the inhibitory avoidance memory in rats

The ventral tegmental area (VTA) is a neural structure that sends strong efferent projections to the hippocampus. Output from the VTA can affect hippocampal-dependent neural processes that are critical for learning and memory, including long term potentiation and theta activity. However, no study to date has elucidated what role the VTA plays in mediating the different stages of learning and memory. Therefore, the current study was designed to assess how reversible inactivation of the VTA may affect the acquisition, consolidation and retrieval of memory in rats using an inhibitory avoidance (IA) task. In this experiment, rats with chronically implanted cannulae aimed at the VTA were trained on an inhibitory avoidance task. They received intra-VTA infusions of lidocaine or saline immediately before training, after training or before a memory retention test. The results indicate that inactivation of the VTA prior to the first acquisition session increased the number of trials rats required to reach the acquisition criterion. Similarly, inactivation of the VTA after acquisition training decreased the step-through latency and increased the amount of time spent in the dark compartment relative to the saline-treated group. However, inactivation of the VTA immediately prior to the memory retention test failed to alter either step-through latency or the amount of time spent in the dark compartment. Overall, these results suggest the VTA facilitates the acquisition and consolidation of IA learning and memory.

Effects of Ketamine on Memory and Nociception in Rats

Ketamine is intravenous anaesthetic with NMDA-glutamate receptors mechanism of action. Male Wistar rats were treated with saline (group A) or 10, 15 or 20 mg/kg of ketamine (groups B, C and D, respectively). For active avoidance test an automatic reflex conditioner was used. The observed variables were number of avoidances, escapes and intertrial crossings. Step-through and step-down passive avoidance tests were done with learning and memory retention test. Criteria for step-through test were latency of reactions of 180 sec in the light chamber. Criteria for step-down test were latency of reaction of 60 sec on the platform. The hot-plate test evaluates the reaction time of the rats dropped on a heated surface. The analgesy-meter test exerts a force increased at constant rate. In active avoidance test the controls increased the number of avoidances during learning and memory tests. Ketamine in all doses used increased the number of avoidances during learning and in memory test. Controls did not change the number of escapes, but the ketamine treated animals decreased it. The number of intertrial crossings was not changed by controls or ketamine-treated rats during learning and memory tests. In passive avoidance tests the controls and ketamine-treated rats increased the latency time during learning and memory retention tests. In hot-plate analgesic test and in analgesy-meter test the controls and ketamine-treated rats did not change the latency of reaction. The results suggest that ketamine improves learning and memory processes and has no analgesic effect in the doses applied.

Post weaning social isolation influences spatial cognition, prefrontal cortical synaptic plasticity and hippocampal potassium ion channels in Wistar rats

Post weaning isolation-reared rats show deficits in learning and memory, which are also seen in many psychiatric disorders like schizophrenia. The present study utilized behavioral and electrophysiological tests to further characterize cognitive disorders in this rat model, and to explore possible neurobiological mechanisms associated with them. Isolation rearing was performed in male Wistar rats from weaning for 8 weeks. Spatial memory and reversal learning were assessed using Morris water maze (MWM); synaptic plasticity was assessed by recording long-term potentiation (LTP) from thalamus to prefrontal cortex; and potassium ion channel currents were tested using the cerebrospinal fluid (CSF) of different groups in hippocampal slices by patch clamp. The results of MWM showed that isolation-reared rats performed worse in probe trials and memory retention tests. The LTP tests showed that the prefrontal cortical postsynaptic potential slopes were significantly lower in isolated rats than group housed ones. The patch clamp recording showed that the amplitudes of hippocampal voltage-dependent transient outward K + currents ( I A) were enhanced, and the steady inactivation curve of I A was shifted towards positive potential by CSF of isolated rats. These data suggested that isolation rearing can impair the spatial cognition of rats, with the possible mechanisms of affecting prefrontal cortical synaptic plasticity and hippocampal potassium ion channel currents.