21 resultados para local field


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SCHEFFZUK, C. , KUKUSHKA, V. , VYSSOTSKI, A. L. , DRAGUHN, A. , TORT, A. B. L. , BRANKACK, J. . Global slowing of network oscillations in mouse neocortex by diazepam. Neuropharmacology , v. 65, p. 123-133, 2013.

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TORT, A. B. L. ; SCHEFFER-TEIXEIRA, R ; Souza, B.C. ; DRAGUHN, A. ; BRANKACK, J. . Theta-associated high-frequency oscillations (110-160 Hz) in the hippocampus and neocortex. Progress in Neurobiology , v. 100, p. 1-14, 2013.

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The processing of spatial and mnemonic information is believed to depend on hippocampal theta oscillations (5–12 Hz). However, in rats both the power and the frequency of the theta rhythm are modulated by locomotor activity, which is a major confounding factor when estimating its cognitive correlates. Previous studies have suggested that hippocampal theta oscillations support decision-making processes. In this study, we investigated to what extent spatial decision making modulates hippocampal theta oscillations when controlling for variations in locomotion speed. We recorded local field potentials from the CA1 region of rats while animals had to choose one arm to enter for reward (goal) in a four-arm radial maze. We observed prominent theta oscillations during the decision-making period of the task, which occurred in the center of the maze before animals deliberately ran through an arm toward goal location. In speed-controlled analyses, theta power and frequency were higher during the decision period when compared to either an intertrial delay period (also at the maze center), or to the period of running toward goal location. In addition, theta activity was higher during decision periods preceding correct choices than during decision periods preceding incorrect choices. Altogether, our data support a cognitive function for the hippocampal theta rhythm in spatial decision making

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The power-law size distributions obtained experimentally for neuronal avalanches are an important evidence of criticality in the brain. This evidence is supported by the fact that a critical branching process exhibits the same exponent t~3=2. Models at criticality have been employed to mimic avalanche propagation and explain the statistics observed experimentally. However, a crucial aspect of neuronal recordings has been almost completely neglected in the models: undersampling. While in a typical multielectrode array hundreds of neurons are recorded, in the same area of neuronal tissue tens of thousands of neurons can be found. Here we investigate the consequences of undersampling in models with three different topologies (two-dimensional, small-world and random network) and three different dynamical regimes (subcritical, critical and supercritical). We found that undersampling modifies avalanche size distributions, extinguishing the power laws observed in critical systems. Distributions from subcritical systems are also modified, but the shape of the undersampled distributions is more similar to that of a fully sampled system. Undersampled supercritical systems can recover the general characteristics of the fully sampled version, provided that enough neurons are measured. Undersampling in two-dimensional and small-world networks leads to similar effects, while the random network is insensitive to sampling density due to the lack of a well-defined neighborhood. We conjecture that neuronal avalanches recorded from local field potentials avoid undersampling effects due to the nature of this signal, but the same does not hold for spike avalanches. We conclude that undersampled branching-process-like models in these topologies fail to reproduce the statistics of spike avalanches.

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This work aims to study the associations as mediating the process of social change and its importance for local development. The hypothesis is that associations, but bring dynamism to the smaller cities and improve the living conditions of their members, relegated to the background social sustainability, understood this as a permanent exercise of mobilization and participation in community life. The assumptions of the study are that the practice group has influenced the processes of local development in Brazilian rural municipalities through the mediation of government programs and projects aimed at combating rural poverty require social organization for their achievement. The concept of local development in this work was rescued from studies of political economy and sociology. But the concepts of collective action and partnerships advêem studies of political participation and social development of the theory of alternative or solidarity. The party consisted of an empirical case study conducted with four associations of farmers in the municipality of Portalegre-RN. Why choose qualitative study was used the technique of semi-structured interviews with the chairmen I members of associations and other actors considered essential to understanding the study (religious leaders, local political power and chairman of the union of rural workers), a total of 20 interviews, in addition to the observations of field and documentary research in records of the.ir own organizations. The survey results show that the performance of groups of farmers are key components and determinants for the production I marketing of agricultural products and for boosting the economy, as well as security for minimum levels of citizenship. Yet we are still in a space purpose of social change, which comes to confirm the initial hypothesis of this work

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The subject of this research is the spiritual religious field, connected with the local cultural perspectives. Its basis is the analysis of two spiritual groups settled in Natal/RN: The Spiritual Group Evangelho no Lar and the Spiritual Center Garimpeiros da Luz . These two groups represent a point of convergence of several sectors of this religion, either through its insertion in the local sphere or in contact to nationally influent leaders, like the mediums Francisco Cândido Xavier and Divaldo Pereira Franco. Then, it aims to reach the potiguar singularities in their spiritualism approaches, looking for an analyses to possible connections between local values and themes from the spiritualism largely developed in Brazil. So, its objective is to act in the scope of influence, references, representations and adaptive practices in a local context, and they signalize special practices . The approaches until now developed refer only to the living of a Brazilian spiritualism, perfectly developed in contact with the catholic substrate, but there s still a gap about the local observation, with its peculiarities, which its research aims to disclosure. The option for a qualitative approach, in perfect relationship with the nature of the questions which were made was considered as an appropriate way to guide the study. To reach this, it will be made an ethnography of the studied groups, not only in the use of open interviews with its members but also in the contact and observation of its religious behavior, for example: meeting for studies of the doctrine, mediunic meetings, public lectures, helping the public in general. As results of this research we can point to the delimitation of local cultural references, which are undeniable, in relation to the identification of RN personalities who are considered coordinators or active spirits in the work performed by the groups. Thus, Auta de Souza, poetess and woman of great religiosity, Augusto Severo de Albuquerque Maranhão, martyr of the aeronautics, Father João Maria, object of popular devotion and Abdias Antônio de Oliveira, ex president of the Spiritual Federation of RN, present themselves as spiritual beings who lead the adaptability to the local context. In such a context, we have to point out the work of mediums, who, having a specific charisma, interacted with the groups in the establishment of these cultural bridges already made in their own contexts (national level), through the work equally possible to be locally reproduced. This and other facts, point out to perspectives of cultural circularity , including referring to a greater linking to sub layers in a true zone that converges and has circulation between an erudite spiritualism with another one, turned to the incorporation of local and popular elements