Expressão de zif-268 durante a aquisição, evocação e extinção de uma memória aversiva

In the behavioral paradigm of discriminative avoidance task, both short and long-term memories have been extensively investigated with behavioral and pharmacological approaches. The aim of the present study was to evaluate, using the abovementioned model, the hippocampal expression of zif-268 - a calcium-dependent immediate early gene involved with synaptic plasticity process - throughout several steps of memory formation, such as acquisition, evocation and extiction. The behavioral apparatus consisted of a modified elevaated plus-maze, with their enclosed arms disposed in "L". A pre-exposure to the maze was made with the animal using all arms enclosed, for 30 minutes, followed by training and test, during 10 minutes each. The between sections interval was 24h. During training, aversive stimuli (bright light and loud noise) were actived whenever the animals entered one of the enclosed armas (aversive arm). Memory acquisiton, retention and extinction were evaluated by the percentage of the total time spent exploring the aversive arm. The parameters evaluated (time spent in the arms and total distance traveled) were estimated with an animal tracking software (Anymaze, Stoelting, USA). Learning during training was estimated by the decrease of the time spent exploring the aversive arm. One hour after the beginning of each section, animals were anaesthetized with sodium-thiopental (i.p.) and perfused with 0.9% heparinized saline solution followed by 4% paraformaldehyde. Brains were cryoprotected with 20% sucrose, separeted in three blocks and frozen. The middle block, containing the hippocampus, was sectioned at 20 micro meters in the coronal plane and the resutant sections were submitted to zif-268 immunohistochemistry. Our results show an increased expression of zif-268 in the dentate gyrus (DG) during the evocation and extinction stages. There is a distinct participation of the DG during the memory evocation, but not during its acquisition. Inaddition, all hippocampal regions (CA1, CA3 and DG) presented an increased zif-268 expression during the process of extinction.

Efeitos da cafeína sobre a memória de saguis (Callithrix jacchus)

Caffeine is considered the most consumed psychostimulant in the world, presenting several central and peripheral effects. In the Central Nervous System the major effect occur by its antagonistic activity at the A1 and A2a subtypes of the adenosine receptors. These receptors are responsible for the slow-wave sleep induction, and their binding, caused by the consumption of foods and beverages that contain caffeine, cause behaviors like increase of alertness, mood and locomotion. The effects of caffeine on memory are still discussed because of the diversity of experimental protocols. Also, it does not have the same effects on all stages of the processing of memory - acquisition, consolidation and recall. Thus, using the marmoset (Callitrhix jacchus) as subject, we aim to evaluate the effects of caffeine on the memory of this primate through the conditioned place preference paradigm, where the animal selects a context by presence of food. This cognitive task consists of five phases. The first phase was two sessions of pre-exposure, in which they were evaluated for preference for any compartment of the apparatus. Then, we proceeded the training, conditioning the animals to the food-present context for 8 days. Then, there was administration of caffeine or placebo (10mg/kg) for 8 consecutive days, during the pre-sleep phase, where the 20 animals were distributed in two groups: placebo and repeated. The forth phase was one day of retraining, a re-exposure of the apparatus to the marmosets followed by the administration of caffeine (for the repeated group and a new group called abstinence) or placebo (for placebo and abstinence groups). Finally, was the test where we evaluated if the subjects learned where the food was present. Moreover, in this work we evaluate the existence of differences between females and males on the task, and the locomotor activity for the experimental groups. The results showed that in the pre-exposure phase the animals were habituated on the apparatus and did not present differences for any contexts. In training, they were able to learn the conditioning task, independent of gender. For the retraining, the two groups exhibited more interactions in rewarded context than that in non-rewarded context. Nevertheless, in the locomotor activity, the repeated group moved similarly in contact with the apparatus and outside of it. In the other hand, the animals of the placebo group moved more when in contact with the apparatus. In the test phase, the marmosets under influence of caffeine presented an increase in the locomotor activity when compared with the placebo group, corroborating works that show this increase in locomotion. In the learning evaluation, the continuous and abstinence groups had a bad performance in the task in relation to the placebo and acute groups. This suggests that the prolonged administration of caffeine disrupts the memories because it affected sleep, which is largely responsible offline processing of memories

Influência do ciclo estral no efeito do diazepam na ansiedade e memória de ratas

Memory and anxiety are related phenomena. Several evidences suggest that anxiety is fundamental for learnining and may facilitate or impair the memory formation process depending of the context. The majority of animal studies of anxiety and fear use only males as experimental subjects, while studies with females are rare in the literature. However, the prevalence in phobic and anxiety disorders is greater in women than in men. Moreover, it is known that gender maybe influence benzodiazepine effects, the classic drugs used for anxiety disorders treatment. In this respect, to further investigate if fear/anxiety aspects related to learning in female subjects would contribute to the study of phobic and anxiety disorders and their relationship with learning/memory processes, the present work investigates (a) the effects of benzodiazepine diazepam on female rats performance in a aversive memory task that assess concomitantly anxiety/emotionality, as the interaction between both; (b) the influence of estrous cycle phases of female rats on diazepam effects at aversive memory and anxiety/emotionality, and the interaction between both and (c) the role of hormonal fluctuations during estrous cycle phases in absence of diazepam effects in proestrus, because female rats in this phase received or not mifepristone, the antagonist of progesterone receptor, previously to the diazepam treatment. For this purpose, the plus maze discriminative avoidance task, previously validated for studies of anxiety concomitantly to learning/memory, was used. The apparatus employed is an adaptation of a conventional plus maze, with two opens arms and two closed arms, one of which presenting aversive stimulation (noise and light). The parameters used were: time in non-aversive arm compared to time in aversive and percentage of time in aversive arm on several temporal divisions, in order to evaluate memory; percentage of time in open arms, risk assessment, head dipping and end exploring to evaluate anxiety ; and distance traveled for locomotion. In experiment I, we found anxiolytic effect of diazepam only for 4 mg/kg dose, however the amnestic effect appear at a dose of 2 mg/kg. In second experiment, rats were divided in groups according estrous cycle phase (metaestrus/diestrus, proestrus e estrus). In this experiment, when we considered estrous cycle phase or diazepam treatment, the results did not demonstrate any differences in anxiety/emotionality parameters. The amnestic effects of diazepam occur in female rats in metestrus/diestrus and estrus and is absent in proestrous rats. Proestrous female rats that received mifepristone exhibited the amnestic effect of diazepam and also anxiolytic effects, that it was not previously observed in this dose. The results have demonstrated dissociation of anxiolytic and amnestic diazepam effects, not previously observed in males; the absence of amnestic effect of diazepam in proestrous phase; and the possible role of progesterone in aversive memory over diazepam effect, because the mifepristone, associated with diazepam, caused amnestic effect in proestrus

Efeito da coesão semântica sobre a discriminação de itens emocionais em testes de memória de reconhecimento de palavras

Highly emotional itens are best remembered in emotional memory tasks than neutral items. An example of emotional item that benefits declarative memory processes are the taboo words. These words undergo from a conventional prohibition, imposed by tradition or custom. Literature suggests that the strongest recollection these words is due to emotional arousal, as well as, the fact that they form a cohesive semantic group, which is a positive additive effect. However, studies with semantic lists show that cohesion can have a negative effect of interference, impairing memory. We analyzed, in two experiments, the effect of arousal and semantic cohesion of taboo words on recognition tests, comparing with into two other word categories: semantically related and without emotional arousal (semantic category) and neutral, with low semantic relation (objects). Our results indicate that cohesion has interfered whith the performance of the test by increasing the number of false alarms. This effect was strongly observed in the semantic category of words in both experiments, but also in the neutral and taboo words, when both were explicitly considered as semantic categories through the instruction of the test in Experiment 2. Despite the impairment induced by semantic cohesion in both experiments, the taboo words were more discriminated than others, and this result agrees with the indication of the emotional arousal as the main factor for the best recollection of emotional items in memory tests

Alterações na evocação de uma memória aversiva ao liongo do ciclo estral de ratas: influências da transmissão gabaérgica na amígdala

GABAergic neurotransmission has been implicated in many aspects of learning and memory, as well as mood and anxiety disorders. The amygdala has been one of the major focuses in this area, given its essential role in modulating emotionally relevant memories. However, studies with male subjects are still predominant in the field. Here we investigated the consequences for an aversive memory of enhancing or decreasing GABAergic transmission in the basolateral nucleus of the amygdala (BLA). Wistar female rats were trained in the plus-maze discriminative avoidance task, in which they had to learn to avoid one of the enclosed arms where an aversive stimulus consisting of a bright light and a loud noise was given (day 1). Fifteen minutes before the test session (day 2) animals received 0,2 μL infusions of either saline solution, the GABAergic agonist muscimol (0,05 mg/ml), or the GABAergic antagonist bicuculine (0,025 mg/ml) bilaterally intra-BLA. On the test day, females in proestrous or estrous presented adequate retrieval and did not extinguish the task, while females in metestrous or diestrous presented impaired retrieval. In the first group, muscimol infusion impaired retrieval and bicuculline had no effect, suggesting naturally low levels of GABAergic transmission in the BLA of proestrous and estrous females. In the second group, muscimol infusion had no effect and bicuculline reversed retrieval impairment, suggesting naturally high levels of GABAergic transmission in the BLA of metestrous and diestous females. Additionally, proestrous and estrous females presented higher anxiety levels compared to metestrous and diestrous females, which could explain better performance of this group. On the other hand, BLA GABAergic system did not interfere with the innate fear response because drug infusions had no effect in anxiety. Thus, retrieval alterations caused by the GABAergic drugs were probably related specifically to memory processes

Memória de reconhecimento em indivíduos adultos com mais de 45 anos

As we grow old, there are many cognitive processes which decline in the human brain. One of them is the memory, a function that allows retention and posterior use of knowledge learned during the life, understood as a result of multiple systems highly organized and spread in several neural regions. This work aimed to evaluate the recognition memory in adults over 45 years old through words and pictures recognition tasks and the use of two codification or learning conditions (same distracters and different distracters). Twelve individuals were studied (6 men and 6 women) aged between 45 and 88 years old and with similar demographic characteristics. They presented better performance on picture tasks rather than word tasks. Better results were also verified when the codification context had different distracters, which significantly reflected in a long term principally in elderly individuals. The results reached suggest that the codification context influenced the lists of pictures and words learning, mainly for the elderly ones, when compared to adults, and that these results can be related to the phenomena involved with the recognition memory, the recollection and familiarity

Efeitos do tratamento com lítio na memória aversiva, comportamentos relacionados à ansiedade e depressão e na expressão de BDNF em ratos

Lithium (Li) is the first choice to treat bipolar disorder, a psychiatric illness characterized by mood oscillations between mania and depression. However, studies have demonstrated that this drug might influence mnemonic process due to its neuroprotector, antiapoptotic and neurogenic effects. The use of Li in the treatment of cognitive deficits caused by brain injury or neurodegenerative disorders have been widely studied, and this drug shows to be effective in preventing or even alleviating the memory impairment. The effects of Li on anxiety and depression are controversial and the relationship of the effects of lithium on memory, anxiety and depression remain unknown. In this context, this study aims to: evaluate the effects of acute and chronic administration of lithium carbonate in aversive memory and anxiety, simultaneously, using the plus maze discriminative avoidance task (PMDAT); test the antidepressant effect of the drug through the forced swimming test (FS) and analyze brainderived neurotrophic factor (BDNF) expression in structures related to memory and emotion. To evaluation of the acute effects, male Wistar rats were submitted to i.p. administration of lithium carbonate (50, 100 or 200 mg/kg) one hour before the training session (PMDAT) or lithium carbonate (50 or 100 mg/kg) one hour before the test session (FS). To evaluation of the chronic effects, the doses administered were 50 or 100 mg/kg or vehicle once a day for 21 days before the beginning of behavioral tasks (PMDAT and FS). Afterwards, the animals were euthanized and their brains removed and submitted to immunohistochemistry procedure to quantify BDNF. The animals that received acute treatment with 100 and 200 mg/kg of Li did not discriminated between the enclosed arms (aversive and non-aversive) in the training session of PMDAT, showing that these animal did not learned the task. This lack of discrimination was also observed in the test session, showing that the animals did not recall the aversive task. We also observed an increased exploration of the open arms of these same groups, indicating an anxiolytic effect. The same groups showed a reduction of locomotor activity, however, this effect does not seem to be related with the anxiolytic effect of the drug. Chronic treatment with Li did not promote alterations on learning or memory processes. Nevertheless, we observed a reduction of open arms exploration by animals treated with 50 mg/kg when compared to the other groups, showing an anxiogenic effect caused by this dose. This effect it is not related to locomotor alterations since there were no alterations in these parameters. Both acute and chronic treatment were ineffective in the FS. Chronic treatment with lithium was not able to modify BDNF expression in hippocampus, amygdala and pre-frontal cortex. These results suggest that acute administration of lithium promote impairments on learning in an aversive task, blocking the occurrence of memory consolidation and retrieval. The reduction of anxiety following acute treatment may have prevented the learning of the aversive task, as it has been found that optimum levels of anxiety are necessary for the occurrence of learning with emotional context. With continued, treatment the animals recover the ability to learn and recall the task. Indeed, they do not show differences in relation to control group, and the lack of alterations on BDNF expression corroborates this result. Possibly, the regimen of treatment used was not able to promote cognitive improvement. Li showed acute anxiolytic effect, however chronic administration 4 promoted the opposite effect. More studies are necessary to clarify the potential beneficial effect of Li on aversive memory

Efeito do alerta e valência emocional nos componentes de lembrança e familiaridade da memória episódica

The episodic memory system allows us to retrieve information about events, including its contextual aspects. It has been suggested that episodic memory is composed by two independent components: recollection and familiarity. Recollection is related to the vivid e detailed retrieval of item and contextual information, while familiarity is the capability to recognize items previously seen as familiars. Despite the fact that emotion is one of the most influent process on memory, only a few studies have investigated its effect on recollection and familiarity. Another limitation of studies about the effect of emotion on memory is that the majority of them have not adequately considered the differential effects of arousal and positive/negative valence. The main purpose of the current work is to investigate the independent effect of emotional valence and arousal on recollection and familiarity, as well as to test some hypothesis that have been suggested about the effect of emotion on episodic memory. The participants of the research performed a recognition task for three lists of emotional pictures: high arousal negative, high arousal positive and low arousal positive. At the test session, participants also rated the confidence level of their responses. The confidence ratings were used to plot ROC curves and estimate the contributions of recollection and familiarity of recognition performance. As the main results, we found that negative valence enhanced the component of recollection without any effect on familiarity or recognition accuracy. Arousal did not affect recognition performance or their components, but high arousal was associated with a higher proportion of false memories. This work highlight the importance of to consider both the emotional dimensions and episodic memory components in the study of emotion effect on episodic memory, since they interact in complex and independent way

Estampa temporal na memória de reconhecimento em estudantes universitários

Several studies have shown that there is a circadian modulation of explicit memory. This modulation can occur independently in each one of the mnemonic processes. The aim of this study was to evaluate the influence of time of training on short-term memory (STM) and long-term memory (LTM), using a recognition task. Moreover, a possible circadian modulation in retrieving was investigated when this process matched the acquisition hour (time stamp). The chronotype variable was also considered. Fifty-seven undergraduate students aging between 18 and 25 years (21,72 ± 2,14; 28 ♂) participated in this study. In the training phase (acquisition) the subjects heard a ten word list. Following this, they answered a recognition test to evaluate STM and one week later they answered a recognition test to evaluate LTM. In each chronotype, the subjects were divided in groups according to the training hour, part of them in the morning and the other in the afternoon. One week later some of the subjects in each group underwent LTM testing in the morning and others in the afternoon. When the subjects performances were analyzed together, independently of the chronotypes, a training hour effect was found in the LTM. The subjects trained in the afternoon had better performance. No time of day effect was found in the STM and in retrieving from the LTM. However, the morning types who were trained and tested in the same hour had a better performance in the LTM when compared to morning types trained and tested in different hours. This effect did not occur when the other chronotypes were analyzed. The circadian modulation seems to occur at least in two different ways. First, there is a circadian modulation in the acquisition/consolidation processes, with a better performance occuring in the afternoon. Secondly, there is a modulation in the retrieval mnemonic process, called time stamp phenomenon. This phenomenon, that occurred in the morning types, is showed for the first time in humans

Arte em cerâmica e a memória como elemento criativo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Processos excludentes no espaço intra-urbano: condição de vida, saúde e redes sociais dos chefes de família desempregados Presidente Prudente-SP

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Infância e memória em When We Were Orphans, de Kazuo Ishiguro

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Processos, fácies e geometria do sistema turbidítico da formação Taciba/Membro Rio Segredo, faixa aflorante norte catarinense

Pós-graduação em Geociências e Meio Ambiente - IGCE

Memória e patrimônio ferroviário: estudo sobre o Museu da Companhia Paulista em Jundiaí-SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Vulnerabilidade Ambiental aos processos erosivos lineares nas áreas rurais do município de Presidente Prudente-SP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)