Undersampled Critical Branching Processes on Small-World and Random Networks Fail to Reproduce the Statistics of Spike Avalanches

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.

Undersampled Critical Branching Processes on Small-World and Random Networks Fail to Reproduce the Statistics of Spike Avalanches

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.

O desenvolvimento profissional docente e a participação colegiado no Atheneu Norte-Riograndense

To investigate the relationship that exists among the educational participation of the school board and the teacher's professional development, starting from the analysis teachers of a public institution who teaches daily in the city of Natal. We focused the possible relationships between the teacher's action and their professional development, which includes the participation of the School board, considered by us as a collective space. To accomplish this research we used Interviews (KAUFMANN, 1996; SILVA, 2002) to analyze the nine participants, who are teachers' of the school board, and their oral speeches, considered as main references of our study. While trying to understand the reasons that led the teachers to choose her/his educational profession, we noticed the difficulty of recognition of the job of lecturing as a profession. This fact comes as an obstacle to the perspective of the teachers' professional development. In what he/she refers to the forms of the teachers' participation in the board and their meanings, we noticed in first place that the feeling of it belongs one of the decisive factors it can be considered actively for the teacher to announce of the actions colegiadas. This for them to want and they believe that that is the best road for if they develop better while professionals and consequently to improve the situation of the school. In second place we noticed that the school board represents, a place of articulation of the equality among all the ones that form the school community. So, we tried to understand how they happened to the collective actions in the school, how the teachers presented them in spite of what they know, how a collective action should be presented in the elements of fragility of that process that inhibit the development of the overall action. Finally, we questioned the elements that would contribute to the educational professional development; we noticed that the teachers present the competence, the ethics and professional valorization, as factors that contributed at the present time to their educational professional development

A natureza da alma e o clinamen: ação e liberdade em Lucrécio

The concept of freedom and his presupposition, the free will or libera voluntas in Lucretius relies on the notion of clinamen (declination), an occasional and random motion of atoms, inaccessible to experience. It is endowed with a complex movement provided by spontaneity, without the need for mechanical causes. The action of perceiving (sensus) is selfconsciousness, according to which this will, illuminated by previous experiences (sensory, intellectual or emotional) of the soul, takes advantage of the freedom and own spontaneity of atomic motions to drive them to a perceived direction and chosen. On the other hand, if we consider that the declination has a predominant role for the acts of will, we are facing other problems and questions. There is always the choice of a determined action and, therefore, even if the individual is facing a need to act, is possible choose to do not continue finish this action. Thereby, the will is related to conditions that are originate, ultimately, from the images formed randomly in space and impress the soul: the simulacra of desire and pleasure. The declination itself is a very important notion in this research, in order to emphasize the relationship between the freedom and the kinetic of elements. The approach developed in this work had as main objective to investigate the philosophy of nature and the soul in Lucretius, their constituents and movement, as well as demonstrating how the notion of clinamen articulates with the concepts of image, desire and pleasure, proposing a possible interpretation for the declination as an indeterminate and ethical foundation of freedom

A questão do estilo na psicanálise lacaniana

Lacanian psychoanalysis has won a considerable space in brazilian university: a search for Lacan in the field of subject of the CAPES Thesis Bank shows 1.032 results! However the difference in the style of knowledge production and language usage is considerable between academic psychology and lacanian theory. The difficulty in reading and understanding Lacan is something pointed out by supporters and critics alike. In addition to that, his disciples choose many times to imitate his baroque, complex style, full of neologisms, causing perplexity in many unprepared audiences. What is the origin of such an enigmatic and polemic style of expression? How it became so widespread under the sign of repetition? And which are the consequences of this style to the communication, transmission and teaching of lacanian psychoanalysis? Through these questions it is our goal to contribute to the dialogue between lacanian psychoanalysis and the academy, to provide a better understanding of the causes of this style, analyzing the consequences it has to the transmission of psychoanalysis. We chose to perform a theoretical study, using authors that have treated Lacan s style and the history of psychoanalysis from a critical point of view, like Beividas (2000), Roustang (1987, 1988) and Gellner (1988), and also those that have defended and justified its legitimacy, like Glynos e Stavrakakis (2001), Fink (1997) and Souza (1985), using as well some works by Freud and Lacan. The study of these texts has led us to three main themes: 1) the difficulty of the lacanian text; 2) Lacan, heir of Freud; 3) consequences of the lacanian style. In the first one, we enumerate many different explanations and interpretations given by commentators about the difficulty and particularity of the lacanian discourse; in the second, we show how Lacan came to occupy the place of great idealization that was before destined to Freud, what made his style something to be taken as a model, to be imitated by disciples; in the third, we explore the way in which the concepts are treated in lacanian psychoanalysis, arguing that their multiple meanings point out that the final goal is not to build a clear and coherent theory, but to try to aim directly at the subject, to catch him

Ser-no-mundo com a criança portadora de câncer compreendendo a experiência de psicólogos nos serviços de oncologia pediátrica de Natal-RN

Cancer goes on to be a frightening disease by humanity, simetimes,it is considered as death, suffering and stigma synonym. Occurring at childhood, this meaning seems to acquire a more intense conotation, having in view of the perplexity and godliness feeling in the presence of the precocity of events, nearly always associated to the death. A psychologist co-existence with the cancer children is going acquiring, thus, a permeated sense by incognitas , fears and fantasy, which raised us the following question: how does the psychologist that answers children with cancer lives this experience? Therefore, the aim this research was to understand this co-existence experience. Our theoretical perspective comes from an existencial fenomenology and, more specifically, the Humanistic Approach and Martin Heidegger Existencial Ontology. The metodology is qualitative of phenomenological character. The access instrument to the experience was the narrative, such as purpose by Walter Benjamin. They were carried out nine semi-open interviews with psychologists who work on pediatric oncology services of Natal-RN city. Such interviews were recorded in cassette, transcripted and later, re-educated. These interviews were recorded, transcribed and later on edited with the help of the interviewee and turned into a text. The narrative comprehension was carried out on Heidegger Existencial Ontology, on dada exaustive reading and the clipping of indicative passages of experience sense of being psychologist on this area. The research suggests that the experience is oriented of clinic kowing-doing, being crossed by implications of key thematics which indicate the care as central ontologic element that orientates the way as these professionals come being in the world in association with the clientèle. Besides, the caring experience of these children acquire the sense of true living experience, since the cancer undoes the immortality illusion, launching the psychologist to his/her condition of being to the death and with that, calling him/her the authenticity. Is is only not dealt with to experience the anguish and the death imminence, but above all, re-meaning them in favour of a continual learning, of quality answering , besides other possibilities. Working with child cancer brings news perspectives and world views, making the psychologist a more human people and sensitive to the distracted needs. And we believe that, regardless of area which actuates, being psychologist is a particular way which choose to be citizen. Is is a project that will be delimited by society, history and culture and after all, by us like human being. Therefore, we understand that the results this research suggest the discussed thematic deepening on this intervention field in order to new sense possibilities can arise giving origin to other reflections about the clinical practice, the professional formation in Psychology and other possible developments