A cafeína exerce efeitos positivos sobre a memória tipo episódica em ratos adultos sem influenciar a sobrevivência neural no giro dentado

The caffeine is a mild psychostimulant that has positive cognitive effects at low doses, while promotes detrimental effects on these processes at higher doses. The episodic-like memory can be evaluated in rodents through hippocampus-dependent tasks. The dentate gyrus is a hippocampal subregion in which neurogenesis occurs in adults, and it is believed that this process is related to the function of patterns separation, such as the identification of spatial and temporal patterns when discriminating events. Furthermore, neurogenesis is influenced spatial and contextual learning tasks. Our goal was to evaluate the performance of male Wistar rats in episodic-like tasks after acute or chronic caffeine treatment (15mg/kg or 30mg/kg). Moreover, we assessed the chronic effect of the caffeine treatment, as well as the influence of the hippocampus-dependent learning tasks, on the survival of new-born neurons at the beginning of treatment. For this purpose, we used BrdU to label the new cells generated in the dentate gyrus. Regarding the acute treatment, we found that the saline group presented a tendency to have better spatial and temporal discrimination than caffeine groups. The chronic caffeine group 15 mg/kg (low dose) showed the best discrimination of the temporal aspect of episodic-like memory, whereas the chronic caffeine group 30mg/kg (high dose) was able to discriminate temporal order, only in a condition of greater difficulty. Assessment of neurogenesis using immunohistochemistry for evaluating survival of new-born neurons generated in the dentate gyrus revealed no difference among groups of chronic treatment. Thus, the positive mnemonic effects of the chronic caffeine treatment were not related to neuronal survival. However, another plastic mechanism could explain the positive mnemonic effect, given that there was no improvement in the acute caffeine groups

Interferindo com oscilações de alta frequência no hipocampo epiléptico: consequências para as crises espontâneas

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Efeitos da administração aguda de quetamina sobre as oscilações eletrofisiológicas da região CA1 hipocampal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Diferenças funcionais das regiões hipocampais na formação da memória do tipo o quê", "quando" e "onde" em ratos

Episodic memory refers to the recollection of what, where and when a specific event occurred. Hippocampus is a key structure in this type of memory. Computational models suggest that the dentate gyrus (DG) and the CA3 hippocampal subregions are involved in pattern separation and the rapid acquisition of episodic memories, while CA1 is involved in memory consolidation. However there are few studies with animal models that access simultaneously the aspects ‗what-where-when . Recently, an object recognition episodic-like memory task in rodents was proposed. This task consists of two sample trials and a test phase. In sample trial one, the rat is exposed to four copies of an object. In sample trial two, one hour later, the rat is exposed to four copies of a different object. In the test phase, 1 h later, two copies of each of the objects previously used are presented. One copy of the object used in sample trial one is located in a different place, and therefore it is expected to be the most explored object.However, the short retention delay of the task narrows its applications. This study verifies if this task can be evoked after 24h and whether the pharmacological inactivation of the DG/CA3 and CA1 subregions could differentially impair the acquisition of the task described. Validation of the task with a longer interval (24h) was accomplished (animals showed spatiotemporal object discrimination and scopolamine (1 mg/kg, ip) injected pos-training impaired performance). Afterwards, the GABA agonist muscimol, (0,250 μg/μl; volume = 0,5 μl) or saline were injected in the hippocampal subregions fifteen minutes before training. Pre-training inactivation of the DG/CA3 subregions impaired the spatial discrimination of the objects (‗where ), while the temporal discrimination (‗when ) was preserved. Rats treated with muscimol in the CA1 subregion explored all the objects equally well, irrespective of place or presentation time. Our results corroborate the computational models that postulate a role for DG/CA3 in spatial pattern separation, and a role for CA1 in the consolidation process of different mnemonic episodes

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.

Caracterização de células de lugar no hipocampo e de suas relações com oscilações do potencial de campo local

The main inputs to the hippocampus arise from the entorhinal cortex (EC) and form a loop involving the dentate gyrus, CA3 and CA1 hippocampal subfields and then back to EC. Since the discovery that the hippocampus is involved in memory formation in the 50's, this region and its circuitry have been extensively studied. Beyond memory, the hippocampus has also been found to play an important role in spatial navigation. In rats and mice, place cells show a close relation between firing rate and the animal position in a restricted area of the environment, the so-called place field. The firing of place cells peaks at the center of the place field and decreases when the animal moves away from it, suggesting the existence of a rate code for space. Nevertheless, many have described the emergence of hippocampal network oscillations of multiple frequencies depending on behavioral state, which are believed to be important for temporal coding. In particular, theta oscillations (5-12 Hz) exhibit a spatio-temporal relation with place cells known as phase precession, in which place cells consistently change the theta phase of spiking as the animal traverses the place field. Moreover, current theories state that CA1, the main output stream of the hippocampus, would interplay inputs from EC and CA3 through network oscillations of different frequencies, namely high gamma (60-100 Hz; HG) and low gamma (30-50 Hz; LG), respectively, which tend to be nested in different phases of the theta cycle. In the present dissertation we use a freely available online dataset to make extensive computational analyses aimed at reproducing classical and recent results about the activity of place cells in the hippocampus of freely moving rats. In particular, we revisit the debate of whether phase precession is due to changes in firing frequency or space alone, and conclude that the phenomenon cannot be explained by either factor independently but by their joint influence. We also perform novel analyses investigating further characteristics of place cells in relation to network oscillations. We show that the strength of theta modulation of spikes only marginally affects the spatial information content of place cells, while the mean spiking theta phase has no influence on spatial information. Further analyses reveal that place cells are also modulated by theta when they fire outside the place field. Moreover, we find that the firing of place cells within the theta cycle is modulated by HG and LG amplitude in both CA1 and EC, matching cross-frequency coupling results found at the local field potential level. Additionally, the phase-amplitude coupling in CA1 associated with spikes inside the place field is characterized by amplitude modulation in the 40-80 Hz range. We conclude that place cell firing is embedded in large network states reflected in local field potential oscillations and suggest that their activity might be seen as a dynamic state rather than a fixed property of the cell.

Simulador de dano à formação, aplicado ao Projeto e à execução da perfuração de poços de petróleo

With the high oil price variability, the petroleum and the reservoir engineers are usually face to face on how they can evaluate the well performance and productivity. They can improve high productivity from the well construction to the secondary recoveries, but they have never tried a measurement in the drilling operations about the lower productivity index. As a rule, frequently the drilling operations hear from the reservoir engineering and geology that, if there is a formation damage, probably some drilling operations practices were not done properly or the good practice in petroleum engineering or mud engineering were not observed. The study in this working search is an attempt of how to measure a formation damage just from the project drilling to the drilling operations, with datum from the fields in Brazilian northeast and putting into practice a Simulator developed from the modeling on the theory offered by different experts and sources in formation damage

Geometria e simetria nas rendas de bilro: contribuições para matemática escolar

A tese tem como objetivo descrever e analisar características e princípios dos padrões das rendas de bilro de modo a estabelecer relações com a Matemática escolar, principalmente, no que se refere aos tópicos como Geometria, simetria, isometria, área, perímetro, entre outros. Desse modo, elaboramos atividades didáticas, com base na Matemática explorada nos padrões da criação da renda de bilro, visando concretizar um exercício investigatório nas aulas de Matemática, de modo que, sejam estabelecidas relações conceituais entre a prática investigada e os conteúdos da Matemática escolar. Para satisfazer esses objetivos, buscamos apoio metodológico na pesquisa bibliográfica, do tipo documental em catálogos como o da Professora Valdelice Girão (1984) e também o de Dawson (1984). Realizamos também a pesquisa empírica durante as visitas ao Museu do Ceará e ao Centro das Rendeiras na Prainha, em Aquiraz, no Ceará. Para realizar as atividades didáticas, apoiamo-nos em Mendes (2009). Consideramos relevante essa abordagem de ensino porque pressupõe a experiência direta do aprendiz com situações reais vivenciadas, nas quais a abordagem instrucional é centrada no aluno. Desse modo, concluímos que para o ensino de conteúdos como Geometria, simetria, isometria, relação entre perímetro e área, entre outros que são abordados na Educação Básica, os modelos decorrentes da criação renda de bilro e outros modelos já descritos na tradição cearense podem ser usados como artefato cultural na criação de atividades didáticas

Fresamento com ar quente: uma proposta para minimizar a formação de trincas térmicas em ferramentas de metal duro

This work presents the results, analyses and conclusions about a study carried out with objective of minimizing the thermal cracks formation on cemented carbide inserts during face milling. The main focus of investigation was based on the observation that milling process is an interrupted machining process, which imposes cyclic thermal loads to the cutting tool, causing frequent stresses changes in its superficial and sub-superficial layers. These characteristics cause the formation of perpendicular cracks from cutting edge which aid the cutting tool wear, reducing its life. Several works on this subject emphasizing the thermal cyclic behavior imposed by the milling process as the main responsible for thermal cracks formation have been published. In these cases, the phenomenon appears as a consequence of the difference in temperature experienced by the cutting tool with each rotation of the cutter, usually defined as the difference between the temperatures in the cutting tool wedge at the end of the cutting and idle periods (T factor). Thus, a technique to minimize this cyclic behavior with objective of transforming the milling in an almost-continuous process in terms of temperature was proposed. In this case, a hot air stream was applied into the idle period, during the machining process. This procedure aimed to minimize the T factor. This technique was applied using three values of temperature from the hot air stream (100, 350 e 580 oC) with no cutting fluid (dry condition) and with cutting fluid mist (wet condition) using the hot air stream at 580oC. Besides, trials at room temperature were carried out. Afterwards the inserts were analyzed using a scanning electron microscope, where the quantity of thermal cracks generated in each condition, the wear and others damages was analyzed. In a general way, it was found that the heating of the idle period was positive for reducing the number of thermal cracks during face milling with cemented carbide inserts. Further, the cutting fluid mist application was effective in reducing the wear of the cutting tools.

Alterações da default mode network provocadas pela ingestão de Ayahuasca investigadas por Ressonância Magnética Funcional

Ayahuasca is psychotropic beverage that has been used for ages by indigenous populations in South America, notably in the Amazon region, for religious and medicinal purposes. The tea is obtained by the decoction of leaves from the Psychotria viridis with the bark and stalk of a shrub, the Banisteriopsis caapi. The first is rich in N-N-dimethyltryptamine (DMT), which has an important and well-known hallucinogenic effect due to its agonistic action in serotonin receptors, specifically 5-HT2A. On the other hand, β-carbolines present in B. caapi, particularly harmine and harmaline, are potent monoamine oxidase inhibitors (MAOi). In addition, the tetrahydroharmine (THH), also present in B. caapi, acts as mild selective serotonin reuptake inhibitor and a weak MAOi. This unique composition induces a number of affective, sensitive, perceptual and cognitive changes in individuals under the effect of Ayahuasca. On the other hand, there is growing interest in the Default Mode Network (DMN), which has been consistently observed in functional neuroimaging studies. The key components of this network include structures in the brain midline, as the anterior medial frontal cortex, ventral medial frontal cortex, posterior cingulate cortex, precuneus, and some regions within the inferior parietal lobe and middle temporal gyrus. It has been argued that DMN participate in tasks involving self-judgments, autobiographical memory retrieval, mental simulations, thinking in perspective, meditative states, and others. In general, these tasks require an internal focus of attention, hence the conclusion that the DMN is associated with introspective mental activity. Therefore, this study aimed to evaluate by functional magnetic resonance imaging (fMRI) changes in DMN caused via the ingestion of Ayahuasca by 10 healthy subjects while submitted to two fMRI protocols: a verbal fluency task and a resting state acquisition. In general, it was observed that Ayahuasca causes a reduction in the fMRI signal in central nodes of DMN, such as the anterior cingulate cortex, the medial prefrontal cortex, the posterior cingulate cortex, precuneus and inferior parietal lobe. Furthermore, changes in connectivity patterns of the DMN were observed, especially a decrease in the functional connectivity of the precuneus. Together, these findings indicate an association between the altered state of consciousness experienced by individuals under the effect of Ayahuasca, and changes in the stream of spontaneous thoughts leading to an increased introspective mental activity

A produção de biodiesel no assentamento Canudos RN: perspectivas e limites da inclusão social

The need to become energy self-sufficient a country with which Brazil has sought renewable energy sources due to the possibility of depletion of oil in coming decades. This paper will examine the perspective of social inclusion the latest energy plan developed by the Federal Government: the National Program of Biodiesel Production and Use - PNPB. It aims to find out whether that work with family farmers who participated in the PNPB socially included and what limits its inclusion. Secondly, the objective is to analyze the Brazilian biodiesel production and its uses. The methodology used for the preparation of this study was to examine the literature, visits to the study area, conducting interviews with the leadership of the settlement, questionnaires and semi-structured interviews with families producing sunflower. Finally, the research dealt with the statistical data. After analyzing the data was verified that the instrument PNPB is able to promote the social inclusion of family farmers, but this occurred in the initial stages because the families involved need a minimum framework of organization and infrastructure to develop activities related to biodiesel

Efeito agudo da respiração abdominal lenta sobre a atividade cerebral, respostas emocionais e cardiovasculares

Introduction: Slow abdominal breathing (SAB) stimulates baroreflex and generates respiratory sinus arrhythmia, changing cardiovascular, emotional and cerebral systems acute and chronically. However, although meditative practices have been receiving increasingly attention in the last years, there is no agreement on the neurophysiological changes underlying them, mainly because of the lack of topographical pieces of information. Purpose: We aimed to analyze the acute effect of SAB on brain activity, emotional and cardiovascular responses in untrained subjects in meditative techniques. Methods: Seventeen healthy adults’ men were assessed into two different sessions in a random and crossed order. Into experimental session, they breathed in 6 cycles/minute and in control session they kept breathing in normal rate, both for 20 minutes. xi Before, during, and after each session we assessed brain activity using electroencephalography (EEG), anxiety, mood, heart rate variability (HRV) and blood pressure. The sLORETA software was used to analyze EEG data for source localization of brain areas in which activity was changed. Results: The sLORETA showed that beta band frequency was reduced in frontal gyrus (P<0.01) and anterior cingulate cortex (P<0.05) both during and after SAB (P<0.05) compared to the moment before it. There was no change in brain activity in control session. Additionally, a two-way repeated measures ANOVA showed that there was no effect on anxiety (P>0.8) and mood (P>0.08). There were improvements in HRV (P<0.03), with increased RR interval and decreased HR after SAB, as well as increased SDNN, RMSSD, pNN50, low frequency, LF/HF ratio, and total power during it, with no changes in SBP and DBP. Conclusions: We conclude that SAB is able to change brain activity in areas responsible for emotional processing, even without behavioral changes. Furthermore, SAB improves HRV and does not change blood pressure in normotensive.

Influência da seca extrema na dinâmica fitoplanctônica de um reservatório da região tropical semiárida: uma abordagem morfofuncional

Droughts are climatic phenomena whose frequency has increased in the last decades and also compromised drinkable water supplies in semiarid regions. The lack of rain combined with high evaporation rates promotes a significant reduction of the volume of reservoirs in these regions. Shallower conditions favors nutrients concentration and phytoplankton overgrowth, including potentially toxic cyanobacteria blooming. Therefore, there is a tendency to the intensification of eutrophication in those reservoirs during drought periods. Phytoplankton can respond quickly to environmental conditions related to light and nutrient availability by changes in algal biomass and composition, therefore it is considered a good predictor of environmental variables. Two functional approaches - Reynolds’s Functional Groups (FG) and Kruk’s Morphologically Based Functional Groups (MBFG) - were used to assess which environmental variables were responsible for phytoplankton dynamics, in addition to compare which functional approach explains environmental changes better. This study highlights that the reduction of 90% in the volume of a tropical reservoir of Brazilian semi-arid region, as well as light limitation and nutrient increase, can promote phytoplankton overgrowth. Multivariate analyses using both functional approaches indicated a clear separation between high volumes and low volumes conditions, showing that light and nutrient availability were the main variables that better explained the combination of functional groups. The composition of phytoplankton assemblage changed from species of meso-eutrophic habitats (FG: F and J; MBFG: VI), to organisms of eutrophic and turbid environments (FG: SN and M; MBFG: VIII and VII) during shallower conditions. Both ecological approaches described properly the phytoplankton dynamics according to light and trophic state alterations related to the water volume reduction, therefore they can be considered as equivalent approaches for using in similar environments.

Efeitos do treino de marcha em esteira com adição de carga ao membro inferior não parético de indivíduos com acidente vascular cerebral: ensaio clínico controlado e randomizado

Introduction: Gait after stroke is characterized by a significant asymmetry between the lower limbs, with predominant use of the non-paretic lower limb (NPLL) over using the paretic lower limb. Accordingly, it has been suggested that adding load/weight to the NPLL as a form of restricting the movement of this limb may favor the use of the paretic limb, reducing interlimb asymmetry. However, few studies have been conducted up to this moment, which only investigated the immediate effects of this practice. Objectives: 1) Investigating whether there is an influence of adding load to the NPLL during treadmill training on cardiovascular parameters and on gait performance of individuals with stroke, compared to treadmill training without load addition; 2) Analyzing the effects of treadmill training with and without load added to the NPLL on kinematic parameters of each lower limb during gait; 3) Analyzing the effects of treadmill training with and without load added to the NPLL on measurements of functional mobility and postural balance of these patients. Materials and Methods: This is a randomized single blinded clinical trial involving 38 subjects, with a mean age of 56.5 years, at the subacute post-stroke phase (with mean time since stroke of 4.5 months). Participants were randomly assigned into an experimental group (EG) or control group (CG). EG (n= 19) was submitted to gait training on a treadmill with the addition of load to the NPLL by ankle weights equivalent to 5% of body weight. CG (n= 19) was only submitted to gait training on a treadmill. Behavioral strategies which included home exercises were also applied to both groups. The interventions occurred daily for two consecutive weeks (Day 1 to Day 9), being of 30 minutes duration each. Outcome measures: postural balance (Berg Functional Balance Scale – BBS), functional mobility (Timed Up and Go – TUG; kinematic variables of 180° turning) and kinematic gait variables were assessed at baseline (Day 0), after four training sessions (Day 4), after nine training sessions (Day 9), and 40 days after completion of training (Follow-up). Cardiovascular parameters (mean arterial pressure and heart rate) were evaluated at four moments within each training session. Analysis of variance (ANOVA) was used to compare outcomes between EG and CG in the course of the study (Day 0, Day 4, Day 9 and Follow-up). Unpaired t-tests allowed for intergroup comparison at each training session. 5% significance was used for all tests. Results: 1) Cardiovascular parameters (systemic arterial pressure, heart rate and derivated variables) did not change after the interventions and there were no differences between groups within each training session. There was an improvement in gait performance, with increased speed and distance covered, with no statistically significant difference between groups. 2) After the interventions, patients had increased paretic and non-paretic step lengths, in addition to exhibiting greater hip and knee joint excursion on both lower limbs. The gains were observed in the EG and CG, with no statistical difference between the groups and (mostly) maintained at follow-up. 3) After the interventions, patients showed better postural balance (higher scores on BBS) and functional mobility (reduced time spent on the TUG test and better performance on the 180° turning). All gains were observed in the EG and CG, with no statistically significant difference between groups and were maintained at follow-up. Conclusions: The addition of load to the NPLL did not affect cardiovascular parameters in patients with subacute stroke, similar to treadmill training without load, thus seemingly a safe training to be applied to these patients. However, the use of the load did not bring any additional benefits to gait training. The gait training program (nine training sessions on a treadmill + strategies and exercises for paretic limb stimulation) was useful for improving gait performance and kinematics, functional mobility and postural balance, and its use is suggested to promote the optimization of these outcomes in the subacute phase after stroke.

Simulador de dano à formação, aplicado ao Projeto e à execução da perfuração de poços de petróleo

With the high oil price variability, the petroleum and the reservoir engineers are usually face to face on how they can evaluate the well performance and productivity. They can improve high productivity from the well construction to the secondary recoveries, but they have never tried a measurement in the drilling operations about the lower productivity index. As a rule, frequently the drilling operations hear from the reservoir engineering and geology that, if there is a formation damage, probably some drilling operations practices were not done properly or the good practice in petroleum engineering or mud engineering were not observed. The study in this working search is an attempt of how to measure a formation damage just from the project drilling to the drilling operations, with datum from the fields in Brazilian northeast and putting into practice a Simulator developed from the modeling on the theory offered by different experts and sources in formation damage