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‣ Avaliação em ambientes virtuais de aprendizagem: desafios para uma abordagem colaborativa

Dantas, Eugenia Maria; Araújo, Célia Maria
Fonte: Universidade Aberta; LE@D Publicador: Universidade Aberta; LE@D
Tipo: Conferência ou Objeto de Conferência
Publicado em /12/2013 Português
Relevância na Pesquisa
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A contemporaneidade se caracteriza pelas tecnologias acessíveis a usuários comuns. Diferentes dispositivos, como computadores, celulares, câmeras digitais, jogos eletrônicos, estão interligados por meio da internet, favorecendo a comunicação em rede. A capacidade de operacionalização por meio de interações não lineares impõe a necessidade de refletir sobre estratégias relacionadas aos processos de ensino-aprendizagem e da avaliação. Destaca-se, nesse contexto, ambientes cujo uso se volta para atender finalidades educacionais, como é o caso do Moodle. Compreender como esse ambiente tem sido utilizado enquanto ferramenta colaborativa nos processos de ensino-aprendizagem e na avaliação se constitui o objetivo deste trabalho. A base empírica assenta-se na experiência do ensino a distância da Universidade Federal do Rio Grande do Norte, Brasil, mais especificamente no curso de Geografia a Distância, desde 2007. Dessa forma, questiona-se: as tecnologias da informação e da comunicação potencializam os procedimentos didático-pedagógicos no processo de ensino-aprendizagem e da avaliação? Como elas têm sido utilizadas para favorecer uma avaliação enquanto processo que envolve a organização da informação...

‣ Educação a distância na informação em saúde: o ensino do EPI INFO; Distance Learning in Health Information: Teaching Epi Info

Figueiredo, Marcia Aparecida
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/06/2007 Português
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Esta investigação verificou a aplicabilidade da Educação a Distância com vistas a instrumentar um público de acadêmicos, docentes e profissionais da área de saúde, para o uso do programa de banco de dados e estatística EPI INFO. Os objetivos da investigação foram planejar o conteúdo programático e implementar um curso online sobre construção e manuseio de banco de dados de estatística EPI INFO, verificar as facilidades e as dificuldades na implantação da Educação a Distância (EaD) e descrever a avaliação dos alunos relativa ao Curso no Ambiente Virtual de Aprendizagem. O Ambiente Virtual de Aprendizagem (AVA) utilizado para desenvolvimento do Curso foi CoL (Cursos Online). O conteúdo foi desenvolvido e organizado em quatro unidades: Unidade 1: Criação do Questionário; Unidade 2: Entrando com Dados; Unidade 3: Gerenciamento Básico de Dados na Análise; Unidade 4: Análise Intermediária: Estatísticas Básicas e Recuperação dos Dados. Foram inscritos 32 alunos; destes, 10 participaram efetivamente. Os alunos que completaram o Curso avaliaram de maneira satisfatória a utilização da Internet como ferramenta de aprendizado. O Curso Epi Info desenvolvido na modalidade a distância apresentou, nos itens avaliados...

‣ Dinâmica do sistema córtico-hipocampal durante o condicionamento contextual de medo; Cortico-hippocampal system dynamics during contextual fear conditioning

Kunicki, Ana Carolina Bione
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/02/2012 Português
Relevância na Pesquisa
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O estabelecimento das memórias de longo prazo requer uma efetiva comunicação do hipocampo com o neocortex. Um mecanismo plausível envolvido na comunicação neuronal e na plasticidade sináptica é a sincronização da atividade elétrica cerebral na frequência teta. Estudos recentes mostraram que a sincronização entre os ritmos teta do hipocampo e do córtex pré-frontal aumenta durante a evocação das memórias aversivas e diminui após a extinção do aprendizado. Entretanto, outros ritmos cerebrais, como as ondas delta, também estão envolvidos nas respostas comportamentais do medo e nos processos de memória. Desta forma, o ritmo teta, que já foi bastante estudado pelo seu papel no aprendizado e na memória, e o ritmo delta, por seu envolvimento no ciclo sono-vigília, foram investigados considerando a relação causal entre eles. Ainda não está bem estabelecido como os ritmos delta e teta podem juntos contribuir nos processos cognitivos ou como os ritmos do hipocampo podem influenciar ou receber influencias da atividade cortical. Neste trabalho foi investigada a contribuição dos ritmos delta e teta em função do estado comportamental (vigília ativa ou congelamento) e do tipo de memória evocada (recente ou remota). Além disso...

‣ Projeto Fénix : sentidos de um projeto emergente : a constituição de caminhos conducentos ao sucesso escolar

Moreira, Maria Luísa Pinho Teixeira das Neves Tavares
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Tese de Doutorado
Publicado em 17/05/2013 Português
Relevância na Pesquisa
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A escola inclusiva prevê que todos os alunos tenham as mesmas oportunidades de aprendizagem e de sucesso educativo. Dar o mesmo a todos não nos parece que seja um princípio de equidade e de justiça. Os alunos são diferentes, possuem ritmos de aprendizagem diferentes e, como tal, a escola deve organizar-se no sentido de facultar esta diferenciação que conduza aos princípios anteriormente enunciados – equidade e justiça. Foi nesta premissa que desenhamos, no Agrupamento de Escolas de Beiriz, o Projeto Fénix. Neste seguimento, desenvolveu-se um estudo, a nível nacional com a aplicação de provas a alunos do 2º ano do 1º ciclo, nas áreas de Matemática e Língua Portuguesa. O grupo controlo foi constituído por alunos de 5 Agrupamentos de Escolas Não Fénix e o grupo experimental por alunos de 5 Agrupamentos de Escola com o Projeto Fénix, aplicando-se, no total, 840 provas. Para ajudar a delinear e a estruturar esta investigação, formularam-se quatro objetivos orientadores: i) Avaliar a perceção de alunos e agentes educativos quanto ao impacto da utilização da tecnologia organizacional do Projeto Fénix no sucesso escolar dos alunos e na melhoria organizacional de escola; ii) Identificar em que medida é que os resultados dos alunos do 2º ano do 1º ciclo do ensino básico se diferenciam em função da intervenção do Projeto Fénix; iii) Identificar em que contextos sociodemográficos o Projeto Fénix assume maior impacto; iv) Avaliar a capacidade de transversalidade do Projeto ao longo dos ciclos do ensino básico quanto ao sucesso escolar. Optou-se por uma metodologia de investigação mista. As principais técnicas e instrumentos de recolha de dados consistiram na aplicação de pré teste e de um pós teste aplicado...

‣ Learning-related coordination of striatal and hippocampal theta rhythms during acquisition of a procedural maze task

DeCoteau, William E.; Thorn, Catherine; Gibson, Daniel J.; Courtemanche, Richard; Mitra, Partha; Kubota, Yasuo; Graybiel, Ann M.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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The striatum and hippocampus are conventionally viewed as complementary learning and memory systems, with the hippocampus specialized for fact-based episodic memory and the striatum for procedural learning and memory. Here we directly tested whether these two systems exhibit independent or coordinated activity patterns during procedural learning. We trained rats on a conditional T-maze task requiring navigational and cue-based associative learning. We recorded local field potential (LFP) activity with tetrodes chronically implanted in the caudoputamen and the CA1 field of the dorsal hippocampus during 6–25 days of training. We show that simultaneously recorded striatal and hippocampal theta rhythms are modulated differently as the rats learned to perform the T-maze task but nevertheless become highly coherent during the choice period of the maze runs in rats that successfully learned the task. Moreover, in the rats that acquired the task, the phase of the striatal–hippocampal theta coherence was modified toward a consistent antiphase relationship, and these changes occurred in proportion to the levels of learning achieved. We suggest that rhythmic oscillations, including theta-band activity, could influence not only neural processing in cortico-basal ganglia circuits but also dynamic interactions between basal ganglia-based and hippocampus-based forebrain circuits during the acquisition and performance of learned behaviors. Experience-dependent changes in coordination of oscillatory activity across brain structures thus may parallel the well known plasticity of spike activity that occurs as a function of experience.

‣ Hippocampal-dependent learning requires a functional circadian system

Ruby, Norman F.; Hwang, Calvin E.; Wessells, Colin; Fernandez, Fabian; Zhang, Pei; Sapolsky, Robert; Heller, H. Craig
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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Decades of studies have shown that eliminating circadian rhythms of mammals does not compromise their health or longevity in the laboratory in any obvious way. These observations have raised questions about the functional significance of the mammalian circadian system, but have been difficult to address for lack of an appropriate animal model. Surgical ablation of the suprachiasmatic nucleus (SCN) and clock gene knockouts eliminate rhythms, but also damage adjacent brain regions or cause developmental effects that may impair cognitive or other physiological functions. We developed a method that avoids these problems and eliminates rhythms by noninvasive means in Siberian hamsters (Phodopus sungorus). The present study evaluated cognitive function in arrhythmic animals by using a hippocampal-dependent learning task. Control hamsters exhibited normal circadian modulation of performance in a delayed novel-object recognition task. By contrast, arrhythmic animals could not discriminate a novel object from a familiar one only 20 or 60 min after training. Memory performance was not related to prior sleep history as sleep manipulations had no effect on performance. The GABA antagonist pentylenetetrazol restored learning without restoring circadian rhythms. We conclude that the circadian system is involved in memory function in a manner that is independent of sleep. Circadian influence on learning may be exerted via cyclic GABA output from the SCN to target sites involved in learning. Arrhythmic hamsters may have failed to perform this task because of chronic inhibitory signaling from the SCN that interfered with the plastic mechanisms that encode learning in the hippocampus.

‣ Cognitive Performance as a Zeitgeber: Cognitive Oscillators and Cholinergic Modulation of the SCN Entrain Circadian Rhythms

Gritton, Howard J.; Stasiak, Ashley M.; Sarter, Martin; Lee, Theresa M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 18/02/2013 Português
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The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals that can synchronize or entrain to environmental cues. Although light exerts powerful influences on SCN output, other non-photic stimuli can modulate the SCN as well. We recently demonstrated that daily performance of a cognitive task requiring sustained periods of attentional effort that relies upon basal forebrain (BF) cholinergic activity dramatically alters circadian rhythms in rats. In particular, normally nocturnal rats adopt a robust diurnal activity pattern that persists for several days in the absence of cognitive training. Although anatomical and pharmacological data from non-performing animals support a relationship between cholinergic signaling and circadian rhythms, little is known about how endogenous cholinergic signaling influences SCN function in behaving animals. Here we report that BF cholinergic projections to the SCN provide the principal signal allowing for the expression of cognitive entrainment in light-phase trained animals. We also reveal that oscillator(s) outside of the SCN drive cognitive entrainment as daily timed cognitive training robustly entrains SCN-lesioned arrhythmic animals. Ablation of the SCN, however, resulted in significant impairments in task acquisition...

‣ Machine Learning Helps Identify CHRONO as a Circadian Clock Component

Anafi, Ron C.; Lee, Yool; Sato, Trey K.; Venkataraman, Anand; Ramanathan, Chidambaram; Kavakli, Ibrahim H.; Hughes, Michael E.; Baggs, Julie E.; Growe, Jacqueline; Liu, Andrew C.; Kim, Junhyong; Hogenesch, John B.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 15/04/2014 Português
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Over the last decades, researchers have characterized a set of “clock genes” that drive daily rhythms in physiology and behavior. This arduous work has yielded results with far-reaching consequences in metabolic, psychiatric, and neoplastic disorders. Recent attempts to expand our understanding of circadian regulation have moved beyond the mutagenesis screens that identified the first clock components, employing higher throughput genomic and proteomic techniques. In order to further accelerate clock gene discovery, we utilized a computer-assisted approach to identify and prioritize candidate clock components. We used a simple form of probabilistic machine learning to integrate biologically relevant, genome-scale data and ranked genes on their similarity to known clock components. We then used a secondary experimental screen to characterize the top candidates. We found that several physically interact with known clock components in a mammalian two-hybrid screen and modulate in vitro cellular rhythms in an immortalized mouse fibroblast line (NIH 3T3). One candidate, Gene Model 129, interacts with BMAL1 and functionally represses the key driver of molecular rhythms, the BMAL1/CLOCK transcriptional complex. Given these results, we have renamed the gene CHRONO (computationally highlighted repressor of the network oscillator). Bi-molecular fluorescence complementation and co-immunoprecipitation demonstrate that CHRONO represses by abrogating the binding of BMAL1 to its transcriptional co-activator CBP. Most importantly...

‣ Visuo-motor coordination ability predicts performance with brain-computer interfaces controlled by modulation of sensorimotor rhythms (SMR)

Hammer, Eva M.; Kaufmann, Tobias; Kleih, Sonja C.; Blankertz, Benjamin; Kübler, Andrea
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 06/08/2014 Português
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Modulation of sensorimotor rhythms (SMR) was suggested as a control signal for brain-computer interfaces (BCI). Yet, there is a population of users estimated between 10 to 50% not able to achieve reliable control and only about 20% of users achieve high (80–100%) performance. Predicting performance prior to BCI use would facilitate selection of the most feasible system for an individual, thus constitute a practical benefit for the user, and increase our knowledge about the correlates of BCI control. In a recent study, we predicted SMR-BCI performance from psychological variables that were assessed prior to the BCI sessions and BCI control was supported with machine-learning techniques. We described two significant psychological predictors, namely the visuo-motor coordination ability and the ability to concentrate on the task. The purpose of the current study was to replicate these results thereby validating these predictors within a neurofeedback based SMR-BCI that involved no machine learning.Thirty-three healthy BCI novices participated in a calibration session and three further neurofeedback training sessions. Two variables were related with mean SMR-BCI performance: (1) a measure for the accuracy of fine motor skills, i.e., a trade for a person’s visuo-motor control ability; and (2) subject’s “attentional impulsivity”. In a linear regression they accounted for almost 20% in variance of SMR-BCI performance...

‣ Light as a central modulator of circadian rhythms, sleep and affect

LeGates, T.A.; Fernandez, D.C.; Hattar, S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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Light has profoundly influenced the evolution of life on earth. As widely appreciated, light allows us to generate images of our environment. However, light, through the atypical intrinsically photosensitive retinal ganglion cells (ipRGCs; Box 1), also influences behaviors that are essential for our health and quality of life, yet are independent of image formation. These include the synchronization of the circadian clock to the solar day, tracking of seasonal changes, and regulation of sleep. Irregular light environments lead to problems in circadian rhythms and sleep, which eventually cause mood and learning deficits. Recently, it was found that irregular light can also directly impact mood and learning without producing major disruptions in circadian rhythms and sleep. Here, we will discuss the indirect and direct influence of light on mood and learning and provide a model for how light, the circadian clock, and sleep interact to influence mood and cognitive functions. Box 1Intrinsically photosensitive retinal ganglion cells (ipRGCs)Retinal photoreceptors transduce light energy into electrical signals that initiate vision. The classical photoreceptors, rods and cones, possess modified cilia that consist of stacks of membranes in which photopigments (rhodopsin and cone opsins) are concentrated. Rods are exquisitely sensitive and are able to detect even a few photons. Rods are therefore used for night vision. Cones are less sensitive than rods and are used for day and color vision. Color vision is mediated by cone photoreceptors that express cone-opsins with sensitivity peaks at different wavelengths (colors) of light. Humans have three cone types: short...

‣ State-dependencies of learning across brain scales

Ritter, Petra; Born, Jan; Brecht, Michael; Dinse, Hubert R.; Heinemann, Uwe; Pleger, Burkhard; Schmitz, Dietmar; Schreiber, Susanne; Villringer, Arno; Kempter, Richard
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 26/02/2015 Português
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Learning is a complex brain function operating on different time scales, from milliseconds to years, which induces enduring changes in brain dynamics. The brain also undergoes continuous “spontaneous” shifts in states, which, amongst others, are characterized by rhythmic activity of various frequencies. Besides the most obvious distinct modes of waking and sleep, wake-associated brain states comprise modulations of vigilance and attention. Recent findings show that certain brain states, particularly during sleep, are essential for learning and memory consolidation. Oscillatory activity plays a crucial role on several spatial scales, for example in plasticity at a synaptic level or in communication across brain areas. However, the underlying mechanisms and computational rules linking brain states and rhythms to learning, though relevant for our understanding of brain function and therapeutic approaches in brain disease, have not yet been elucidated. Here we review known mechanisms of how brain states mediate and modulate learning by their characteristic rhythmic signatures. To understand the critical interplay between brain states, brain rhythms, and learning processes, a wide range of experimental and theoretical work in animal models and human subjects from the single synapse to the large-scale cortical level needs to be integrated. By discussing results from experiments and theoretical approaches...

‣ GR3027 antagonizes GABAA receptor-potentiating neurosteroids and restores spatial learning and motor coordination in rats with chronic hyperammonemia and hepatic encephalopathy

Johansson, Maja; Agusti, Ana; Llansola, Marta; Montoliu, Carmina; Strömberg, Jessica; Malinina, Evgenya; Ragagnin, Gianna; Doverskog, Magnus; Bäckström, Torbjörn; Felipo, Vicente
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Português
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Hepatic encephalopathy (HE) is one of the primary complications of liver cirrhosis. Current treatments for HE, mainly directed to reduction of ammonia levels, are not effective enough because they cannot completely eliminate hyperammonemia and inflammation, which induce the neurological alterations. Studies in animal models show that overactivation of GABAA receptors is involved in cognitive and motor impairment in HE and that reducing this activation restores these functions. We have developed a new compound, GR3027, that selectively antagonizes the enhanced activation of GABAA receptors by neurosteroids such as allopregnanolone and 3α,21-dihydroxy-5α-pregnan-20-one (THDOC). This work aimed to assess whether GR3027 improves motor incoordination, spatial learning, and circadian rhythms of activity in rats with HE. GR3027 was administered subcutaneously to two main models of HE: rats with chronic hyperammonemia due to ammonia feeding and rats with portacaval shunts (PCS). Motor coordination was assessed in beam walking and spatial learning and memory in the Morris water maze and the radial maze. Circadian rhythms of ambulatory and vertical activity were also assessed. In both hyperammonemic and PCS rats, GR3027 restores motor coordination...

‣ Prática de ensino supervisionada em educação pré-escolar e 1º ciclo do ensino básico: a diferenciação pedagógica e a qualidade dos processos de aprendizagem

Marques, Patrícia
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Dissertação de Mestrado
Português
Relevância na Pesquisa
37.659214%
O atual relatório retrata e analisa a experiência vivenciada na Prática de Ensino Supervisionada em dois contextos escolares diferentes: Pré-escolar e 1º Ciclo do Ensino Básico revelando um percurso de aprendizagens interligadas no quadro das quatro dimensões contempladas no Perfil de Desempenho Profissional do Educador de Infância e do Professor do 1º Ciclo. Recorrendo à observação participada e participante apurei algumas inferências quanto às características das crianças assim como os seus ritmos de aprendizagem. Logo, foram concebidas estratégias de ensino/aprendizagem adequadas ao grupo. As crianças têm características diferentes e aprendem de maneira distinta, logo o ensino diferenciado foi uma opção que permitiu atender à sua especificidade e permitir o desenvolvimento de aprendizagens mais significativas; ABSTRACT: The present report describes and analyzes the experience in supervised teaching practice in two different contexts: Kindergarten and elementary school revealing it was a journey of interlinked experiences as is described in the four dimensions of the profile performance for the kindergarten teacher and the elementary school teacher. By engaged observation I was able to infer some of the characteristics of the children and their learning rhythms. As a result...

‣ Identificación de las dificultades de regulación del tiempo de los estudiantes universitarios en formación a distancia.; Identification of Time Regulation Difficulties of College Students in Distance Learning.

Romero, Margarida; Barberá, Elena
Fonte: Universidade de Múrcia Publicador: Universidade de Múrcia
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
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Online distance learning allows a high temporal flexibility, whose drawbacks have been scarcely studied. The aim of this study is to identify the temporal difficulties of online learners in the context of distance education in relation to the temporal flexibility of the virtual campus. Students in distance education need to regulate their learning time more than in traditional universities where the learning times are externally regulated by the institution and the faculty. In distance education the learning rhythms and schedules are allocated in a more flexible way by the teacher and the institution. The article discusses the need for a high development of the time self-regulation competency in relation to the temporal flexibility offered by the virtual campus. After that, we introduce the methodology for identifying the time factor difficulties of the participants through a focus group methodology with a sample of tutors with a high degree of experience. The results indicate the lack of planning and time management competencies are considered by tutors as the main difficulty of learners in distance learning.; Estudiar en un campus virtual permite una alta flexibilidad temporal, cuyos inconvenientes han sido poco analizados. El objetivo de este estudio es identificar las dificultades temporales de los estudiantes universitarios en el contexto de la formación a distancia en relación a la flexibilidad temporal del campus virtual. Los estudiantes en formación a distancia necesitan regular sus tiempos de aprendizaje en mayor medida que en la formación presencial...

‣ A aprendizagem baseada em recursos e a promoção da autonomia dos alunos no Quadro da Biblioteca Escolar

Pais, Maria Paula Marques Baptista Coelho
Fonte: Universidade Aberta de Portugal Publicador: Universidade Aberta de Portugal
Tipo: Dissertação de Mestrado
Publicado em //2013 Português
Relevância na Pesquisa
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Dissertação de Mestrado em Gestão da Informação e Bibliotecas Escolares apresentada à Universidade Aberta; A aprendizagem centrada em recursos (resource based learning) envolve uma forte apropriação do processo de ensino-aprendizagem pelos alunos e a tomada de consciência de que o conhecimento é algo de muito pessoal que se vai construindo de acordo com o ritmo de aprendizagem individual e os interesses pessoais. Atual porquanto reconhecedora da importância fundamental da personalidade do aprendente no próprio processo de ensino-aprendizagem, esta metodologia apresenta um grande apelo ao trabalho do mediador enquanto elo de ligação aos recursos, escritos e não escritos e de mobilizador ativo dos estudantes na procura dos mesmos. Profundamente interligada ao aperfeiçoamento das novas tecnologias, novos suportes e novas literacias, responsáveis pela multiplicidade dos recursos disponíveis em contexto educativo, esta abordagem contribuiu igualmente para atenuar o tradicional fosso existente entre professores e alunos no acesso à informação, contribuindo para uma maior acessibilidade e democratização deste caminho. Desempenham aqui um papel fundamental as Bibliotecas Escolares, trabalhando as múltiplas competências afetas às literacias da informação...

‣ Amyloid Beta Peptides Differentially Affect Hippocampal Theta Rhythms In Vitro

Gutiérrez-Lerma, Armando I.; Ordaz, Benito; Peña-Ortega, Fernando
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
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27.461763%
Soluble amyloid beta peptide (Aβ) is responsible for the early cognitive dysfunction observed in Alzheimer's disease. Both cholinergically and glutamatergically induced hippocampal theta rhythms are related to learning and memory, spatial navigation, and spatial memory. However, these two types of theta rhythms are not identical; they are associated with different behaviors and can be differentially modulated by diverse experimental conditions. Therefore, in this study, we aimed to investigate whether or not application of soluble Aβ alters the two types of theta frequency oscillatory network activity generated in rat hippocampal slices by application of the cholinergic and glutamatergic agonists carbachol or DHPG, respectively. Due to previous evidence that oscillatory activity can be differentially affected by different Aβ peptides, we also compared Aβ25−35 and Aβ1−42 for their effects on theta rhythms in vitro at similar concentrations (0.5 to 1.0 μM). We found that Aβ25−35 reduces, with less potency than Aβ1−42, carbachol-induced population theta oscillatory activity. In contrast, DHPG-induced oscillatory activity was not affected by a high concentration of Aβ25−35 but was reduced by Aβ1−42. Our results support the idea that different amyloid peptides might alter specific cellular mechanisms related to the generation of specific neuronal network activities...

‣ Measuring individual locomotor rhythms in honey bees, paper wasps and other similar-sized insects

Giannoni-Guzmán, Manuel A.; Avalos, Arian; Perez, Jaime Marrero; Loperena, Eduardo J. Otero; Kayım, Mehmet; Medina, Jose Alejandro; Massey, Steve E.; Kence, Meral; Kence, Aykut; Giray, Tugrul; Agosto-Rivera, José L.
Fonte: Company of Biologists Publicador: Company of Biologists
Tipo: Artigo de Revista Científica
Publicado em 15/04/2014 Português
Relevância na Pesquisa
27.461763%
Circadian rhythms in social insects are highly plastic and are modulated by multiple factors. In addition, complex behaviors such as sun-compass orientation and time learning are clearly regulated by the circadian system in these organisms. Despite these unique features of social insect clocks, the mechanisms as well as the functional and evolutionary relevance of these traits remain largely unknown. Here we show a modification of the Drosophila activity monitoring (DAM) system that allowed us to measure locomotor rhythms of the honey bee, Apis mellifera (three variants; gAHB, carnica and caucasica), and two paper wasps (Polistes crinitus and Mischocyttarus phthisicus). A side-by-side comparison of the endogenous period under constant darkness (free-running period) led us to the realization that these social insects exhibit significant deviations from the Earth's 24 h rotational period as well as a large degree of inter-individual variation compared with Drosophila. Experiments at different temperatures, using honey bees as a model, revealed that testing the endogenous rhythm at 35°C, which is the hive's core temperature, results in average periods closer to 24 h compared with 25°C (23.8 h at 35°C versus 22.7 h at 25°C). This finding suggests that the degree of tuning of circadian temperature compensation varies among different organisms. We expect that the commercial availability...

‣ Observational Learning of New Movement Sequences Is Reflected in Fronto-Parietal Coherence

van der Helden, Jurjen; van Schie, Hein T.; Rombouts, Christiaan
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 31/12/2010 Português
Relevância na Pesquisa
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Mankind is unique in her ability for observational learning, i.e. the transmission of acquired knowledge and behavioral repertoire through observation of others' actions. In the present study we used electrophysiological measures to investigate brain mechanisms of observational learning. Analysis investigated the possible functional coupling between occipital (alpha) and motor (mu) rhythms operating in the 10Hz frequency range for translating “seeing” into “doing”. Subjects observed movement sequences consisting of six consecutive left or right hand button presses directed at one of two target-buttons for subsequent imitation. Each movement sequence was presented four times, intervened by short pause intervals for sequence rehearsal. During a control task subjects observed the same movement sequences without a requirement for subsequent reproduction. Although both alpha and mu rhythms desynchronized during the imitation task relative to the control task, modulations in alpha and mu power were found to be largely independent from each other over time, arguing against a functional coupling of alpha and mu generators during observational learning. This independence was furthermore reflected in the absence of coherence between occipital and motor electrodes overlaying alpha and mu generators. Instead...

‣ Automated Classification of L/R Hand Movement EEG Signals using Advanced Feature Extraction and Machine Learning

Alomari, Mohammad H.; Samaha, Aya; AlKamha, Khaled
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/12/2013 Português
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In this paper, we propose an automated computer platform for the purpose of classifying Electroencephalography (EEG) signals associated with left and right hand movements using a hybrid system that uses advanced feature extraction techniques and machine learning algorithms. It is known that EEG represents the brain activity by the electrical voltage fluctuations along the scalp, and Brain-Computer Interface (BCI) is a device that enables the use of the brain neural activity to communicate with others or to control machines, artificial limbs, or robots without direct physical movements. In our research work, we aspired to find the best feature extraction method that enables the differentiation between left and right executed fist movements through various classification algorithms. The EEG dataset used in this research was created and contributed to PhysioNet by the developers of the BCI2000 instrumentation system. Data was preprocessed using the EEGLAB MATLAB toolbox and artifacts removal was done using AAR. Data was epoched on the basis of Event-Related (De) Synchronization (ERD/ERS) and movement-related cortical potentials (MRCP) features. Mu/beta rhythms were isolated for the ERD/ERS analysis and delta rhythms were isolated for the MRCP analysis. The Independent Component Analysis (ICA) spatial filter was applied on related channels for noise reduction and isolation of both artifactually and neutrally generated EEG sources. The final feature vector included the ERD...

‣ Learning alters theta amplitude, theta-gamma coupling and neuronal synchronization in inferotemporal cortex

Kendrick, Keith M; Zhan, Yang; Fisher, Hanno; Nicol, Alister U; Zhang, Xuejuan; Feng, Jianfeng
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Artigo de Revista Científica
Português
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RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.; Abstract Background How oscillatory brain rhythms alone, or in combination, influence cortical information processing to support learning has yet to be fully established. Local field potential and multi-unit neuronal activity recordings were made from 64-electrode arrays in the inferotemporal cortex of conscious sheep during and after visual discrimination learning of face or object pairs. A neural network model has been developed to simulate and aid functional interpretation of learning-evoked changes. Results Following learning the amplitude of theta (4-8 Hz), but not gamma (30-70 Hz) oscillations was increased, as was the ratio of theta to gamma. Over 75% of electrodes showed significant coupling between theta phase and gamma amplitude (theta-nested gamma). The strength of this coupling was also increased following learning and this was not simply a consequence of increased theta amplitude. Actual discrimination performance was significantly correlated with theta and theta-gamma coupling changes. Neuronal activity was phase-locked with theta but learning had no effect on firing rates or the magnitude or latencies of visual evoked potentials during stimuli. The neural network model developed showed that a combination of fast and slow inhibitory interneurons could generate theta-nested gamma. By increasing N-methyl-D-aspartate receptor sensitivity in the model similar changes were produced as in inferotemporal cortex after learning. The model showed that these changes could potentiate the firing of downstream neurons by a temporal desynchronization of excitatory neuron output without increasing the firing frequencies of the latter. This desynchronization effect was confirmed in IT neuronal activity following learning and its magnitude was correlated with discrimination performance. Conclusions Face discrimination learning produces significant increases in both theta amplitude and the strength of theta-gamma coupling in the inferotemporal cortex which are correlated with behavioral performance. A network model which can reproduce these changes suggests that a key function of such learning-evoked alterations in theta and theta-nested gamma activity may be increased temporal desynchronization in neuronal firing leading to optimal timing of inputs to downstream neural networks potentiating their responses. In this way learning can produce potentiation in neural networks simply through altering the temporal pattern of their inputs.; Peer Reviewed