Neuronal Assembly Detection and Cell Membership Specification by Principal Component Analysis

LOPES-DOS-SANTOS, V. , CONDE-OCAZIONEZ, S. ; NICOLELIS, M. A. L. , RIBEIRO, S. T. , TORT, A. B. L. . Neuronal assembly detection and cell membership specification by principal component analysis. Plos One, v. 6, p. e20996, 2011.

Selective Coupling between Theta Phase and Neocortical Fast Gamma Oscillations during REM-Sleep in Mice

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.

Detecting cell assemblies in large neuronal populations

Recent progress in the technology for single unit recordings has given the neuroscientific community theopportunity to record the spiking activity of large neuronal populations. At the same pace, statistical andmathematical tools were developed to deal with high-dimensional datasets typical of such recordings.A major line of research investigates the functional role of subsets of neurons with significant co-firingbehavior: the Hebbian cell assemblies. Here we review three linear methods for the detection of cellassemblies in large neuronal populations that rely on principal and independent component analysis.Based on their performance in spike train simulations, we propose a modified framework that incorpo-rates multiple features of these previous methods. We apply the new framework to actual single unitrecordings and show the existence of cell assemblies in the rat hippocampus, which typically oscillate attheta frequencies and couple to different phases of the underlying field rhythm

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.

A Cabana Umbamdista Pai Joaquim de Angola: frente a intolerância a Umbanda na Cidade do Natal/RN

This dissertation presents an attempt to register the initial steps of african-Brazilian religion Umbanda in the city of Natal, capital of Rio Grande do Norte, from a case study of Cabana Umbanda Pai Joaquim de Angola, represented by its maintainer, umbanda of the priest José Clementino. The main objective is to record the memories of fans in aspects of its tradition, experience social and cultural religious building, in an attempt to show the religious hatred with practitioners of Umbanda. Used to: in audio recordings of festivals and rituals, narratives about the memories and stories of employees and their explanations, photographs, diary entries in the field, participant observation and interviews available. The analysis referred to in umbanda Natal / RN, was based on field research as a product of the visits that took place between the years 2006 to 2009 in Terreiro de Umbanda Pai Joaquim de Angola, located in the neighborhood of Rocas.

Ambiente pesqueiro e saúde: representações sociais sobre saúde e doença de pescadores e marisqueiras nos distritos de Diogo Lopes, Barreiras e Sertãozinho Macau RN

According to Brazil s Ministry of Fisheries and Aquaculture, artisanal fishermen are responsible for a significant fish production at national level, highlighting the importance of this activity. In Rio Grande do Norte State, Brazil, fishing has become an important part of economic and social processes. In this context, there are many inland fishing communities such as Barreiras, Diogo Lopes and Sertãozinho, which are part of Ponta do Tubarão State Reserve of Sustainable Development (RDSEPT), located in Macau and Guamaré, Rio Grande do Norte coastline cities. Fishermen and women, the last ones known as marisqueiras who work alongside the menfolk at sea, especially in the shellfish harvest, have been developing narrow relationships with nature, mainly with the sea, from where they extract their families subsistence. However, those communities have been facing several issues related to living conditions, health and diseases. Social representations have been analyzed in the speeches of fishermen/women who were registered active members in a fishermen association named Associação Colônia de Pescadores Z-41, regarding the period from 2008 to 2011. The analysis involved socio-economic profiles verification, identification and analysis of the group s main representative diseases and representations related to health and illness. This study searched for elements in order to provide the comprehension of the relationships among people s social representations and the fishing environment in which they live.. This qualiquantitative study was performed using recordings and transcriptions of structured and open-question interviews. The Collective Subject Speech tecnique proposed by Lefevre & Lefevre (2002) was applied to perform the interviews analysis using QualiQuantiSoft® software. The results showed that health and illness phenomena as well as social representations related to them in the fishing environment are not only abstract states but also physical ones, which interfere in all life extensions, establishing a set of relevant information that indicates that those people realize their own socio-cultural, economic, environmental and political context

Espaços transversais em educação matemática :uma contribuição para a formação de professores na perspectiva etnomatemática

This PH.D. thesis is an attempt to show the beginning, evolution and unfolding of the making of a pedagogical work proposal based on culturally-built knowings in the heart of a traditional community, having as one of its starting points the knowings and doings experienced by dish-making women from Maruanum living in the city of Macapá, State of Amapá, Brazil. This proposal is strongly associated with the need we have to think about the nature of (ethnological)-mathematical knowledge generated by particular communities and about the way such knowledge can be discussed, worked out, and validated in learning environments, regardless of the level of instruction and the constraints imposed by government programs and educational institutions. Among its theoretical foundations are studies on instrumental activities that are typical of the Maruanum ceramics and investigative studies from the point of view of ethnomathematics. Methodological development took place with the application of activities, where traditional and instrumental knowledge observed in the production of ceramics had been adapted for and brought into the school environment , participative observation, as well as data collecting and organization techniques, such as interviews, statements, and audio an visual recordings. Analysis of the data collected focused on the relationship between the data-generating potential and the purpose of this study. Our aim is to make and estimate of the potential contributions from local situations and/or problems it would possibly bring to the formative learning of people involved in the educational processes of these communities, with a view to a spatial and temporal transformation of reality

O ensino da história e o pensamento reflexivo-crítico da professora no 3º ano do Ensino Fundamental

This collaborative research is a qualitative approach, from historical and cultural perspective, made about a teacher of third grade of basic education in the area of history, in the municipality of Caicó / RN. It has as objective to investigate, in a collaborative action, if the design process of teaching and learning the discipline of history based on the relationship before / after allows the development of critical reflective thinking of the teacher in school practices. The theoretical and methodological approaches are supported in the postulates of Vygotsky (1998), Rubinstein (1973) and Linblinskaia (1979), among others, whose understanding has led us to reflect if the teacher develops the reflective critical-thinking in history discipline classes. The complexity of the study led us to an analysis exercise, using different methodological procedures, such as: bibliographic review of the literature, considering also the literature of the history area, interviews, observation in the classroom, video recordings and reflective sessions, enabling clarify the construction and reconstruction of thought that the teacher had been developing during the process of teaching and learning. The test results point to a dichotomy between theory and practice, and also to a certain fragility in the position of professor in teaching and learning the discipline of history, at the third grade of basic education. The teacher recognizes that she requires a theoretical deepening with more intensity, as a process of continuous training to improve the practice of teaching in history school, though, stating in her speech that her teaching practice is based on critical reflection. However, she presents serious limitations in classroom practices. We conclude that, although she has shown willing to work on a critical perspective of reality, showed also poor change at school practices, starting to reflect about her own actions, pointing her limits and the changes needed that didn t become reality yet. It s necessary a formative process for her. The study therefore showed that even with the sessions and reflective of deepening theoretical studies, the teacher does not change its profile, while maintaining its traditional vision in any pedagogical action. This research recommends the formation of school groups for further studies and discussion on the practices of education in history area from a reflective-critical thought perspective as a mean of personal and professional development

A recepção da criança com deficiência intelectual ao texto literário na educação infantil

The focus of this thesis is children's reception to literary texts starting from literary livelihood in an inclusive literary context, looking for the possible evidences that are present in the construction as reader/hearing of literature. Based on a study case, we search the ways of participation of a child (girl) with intellectual deficiency in situations of offering and reception of literary texts, looking for the understanding and explication of some aspects of her processing and the building up of an initial reader. The data were taken starting from observations in moments of reading and story-telling in the period from November to December/2008 and May to June/2009 in a public school of children education, in Natal- Brazil, in which there was a registered student showing intellectual deficiency associated to Down syndrome. As research tools we used: field diary, interview scripts and video recordings. The analyses were based on research from Amarilha (2001, 2006a, 2006b), Bettelheim (2007), Coelho (2008), Iser (1996), Jauss (1979, 1994), Luria (1990a, 1990b), Vygotsky (1991, 1993), Wallon (2007, 2008) amongst others. The research showed that although expressing little verbalization and limited levels of attention, body attitudes, movements and talks of the child under investigation, denounced engagement and rendition to the sonority of the texts shared. These data gives us traces that, under a mediating action, the child with intellectual limitation can turn into a reader/hearing subject of literature, developing a sensitive and a selective attitude towards the literary text. Amongst other aspects, we identified that (1) a conception of deficiency present through the school that recognizes his/her potential of developing and learning (2) the situation of sharing, that favours a relation with the texts through the other, and (3) the relevance of orality providing the semantic paths that help the child in the building up of meaning, presenting themselves as fundamental to her/his viewing of the literary text, and, therefore, the formation of the reader. Thus, recognizing her/his capacity and possibilities, we think it is important to guarantee to the child with intellectual deficiency, a space towards interaction with the fictional text in which the child can learn and live its ludic and interactive character, to enjoy its hearing abilities, benefiting, then, from the aesthetic experience lived, mainly, in collective situations mediated through the more experient reader and shared with her/his different pairs. The research shows yet that, looking after conditions that guarantee a comfortable environment to the story hearings in the classrooms that focus on children education, being aware of a selection and the prosody of stories, the didactic contract, the attention to individual reactions, enlarge the possibility of any child deficient or not to enjoy her/himself as reader/ hearing subject of literature, engaged in its richness and magic

Investigação histórica na formação de professores de matemática: um estudo centrado no conceito de função

In this study we analyzed the development of a teaching experience, involving students with a bachelor s degree in mathematics from UFRN, based on the history of mathematics and mathematical investigations with the aim of contributing to the improvement of the teaching-learning of mathematics. The historical investigation tasks were planned and applied in the classroom, focusing on functional thought. The results obtained during the experience were described and evaluated based on authors who support the assumption of investigation and history as an alternative to the learning of mathematics. We emphasize that the material of analysis consisted of a work diary, audio recordings, questionnaires with testimony of the students involved, and, in addition, the assessment of the teacher of that subject. With regard to the mathematical content, the study was restricted to the concept of function, forms of representation and notation. It was evident that students showed great improvement with regard to the necessary formalization of the mathematical contents which were focused on, and to the active involvement of the students at different stages of the study. We can affirm that the completed study certainly represents significant contributions to an approach in the teaching-learning of functional thought

A etnomatemática em uma cerâmica da região do Seridó/RN

This work has as objective to describe mathematical knowledge used as tools in the manufacture and marketing of tiles of red ceramic by potters of the Currais Novos village/ RN, located 250 km from the capital of Rio Grande do Norte. For us to reach our objective, we rely on conceptions ambrosianas of Ethnomatematics, besides of the qualitative research in an ethnographic approach. In the empirical part of the research, that went it accomplishes in the period from 2009 to 2012 in the Currais Novos Village, we support the following tools for data collection, semi-structured interviews, field diary, photographs, audio recordings and participant observations. In the analysis of the collected data, we can conclude that there are mathematical knowledge in the management of manufacture and marketing of tiles, often different from the academic mathematics, mainly in the wood cube, on cube of the clays, in the handler with the measures time, the count method , in the arrangement of tiles, in the preparation of the ceramic mass and sale of tiles. Theses knowledge were described and analyzed in the light of the theoretical Ethnomatematics, also supported in official documents, such as Parameters Nacional Curriculares. The analyzes of these knowledge generated subsidies for elaboration of an educational product - a proposal of didactic sequence destined to the Teaching of Mathematics in Elementary and Middle levels for the community schools and region, this proposal is in the Appendix to this work

Procedimentos de abertura e fechamento de tópicos na interação em sala de aula

This study is part of interactional perspective, focusing on Conversation Analysis theories, from the Textual Interactive Perspective and Text Linguistics . This research, from its guiding questions, aims at understanding the interaction between teacher and students in the process of the knowledge construction as well as at describing, analyzing and understanding aspects of topical organization speech in the classroom in elementary school, observing the opening and closing procedures of the speech topics in that particular space. Considering that the procedures for opening and closing of discursive topics occur through language marks, we tried to identify which speech marks are used in the opening and closing of the topics studied in the classroom, in interaction during the collaborative process of the discourse established between teacher and students. Therefore, this study is based on authors who analyze specific questions of the text in real context of language use: Koch (1993, 1999), Jubran et al (1991), Jubran (2006), Pine (2005), Penhavel (2010), Galembeck (2012), Barros (1991), Marcuschi (1986 , 1990, 1991 , 1998 , 1999, 2003 , 2004a), Kerbrat - Orecchioni (2006), Favero (1999, 2002) and Galvão (2004, 2010). As a methodology of investigation, the study is focused on the postulates of ethnographic research in order to carry out data collection, through audio and video recordings which were transcribed, according to the NURC project proposal, with some adaptations. Data analysis showed that the procedures for opening and closing of the speech topics occurred by the use of discourse markers, in particular the marker "then", allowing us to understand that these elements are important in the topical organization speech, contributing to ensure textual cohesion and coherence. We conclude that the organization of the discursive topic in the classroom occurs through events that support the explicitness of the content of teaching and learning, considering the diverse necessity of an institutional academic plan, whose main objective is the construction of knowledge

Indicadores de cálcio e de voltagem codificados geneticamente na detecção de potenciais de ação e inputs sinápticos em cultura de neurônios hipocampais

Recently, genetically encoded optical indicators have emerged as noninvasive tools of high spatial and temporal resolution utilized to monitor the activity of individual neurons and specific neuronal populations. The increasing number of new optogenetic indicators, together with the absence of comparisons under identical conditions, has generated difficulty in choosing the most appropriate protein, depending on the experimental design. Therefore, the purpose of our study was to compare three recently developed reporter proteins: the calcium indicators GCaMP3 and R-GECO1, and the voltage indicator VSFP butterfly1.2. These probes were expressed in hippocampal neurons in culture, which were subjected to patchclamp recordings and optical imaging. The three groups (each one expressing a protein) exhibited similar values of membrane potential (in mV, GCaMP3: -56 ±8.0, R-GECO1: -57 ±2.5; VSFP: -60 ±3.9, p = 0.86); however, the group of neurons expressing VSFP showed a lower average of input resistance than the other groups (in Mohms, GCaMP3: 161 ±18.3; GECO1-R: 128 ±15.3; VSFP: 94 ±14.0, p = 0.02). Each neuron was submitted to current injections at different frequencies (10 Hz, 5 Hz, 3 Hz, 1.5 Hz, and 0.7 Hz) and their fluorescence responses were recorded in time. In our study, only 26.7% (4/15) of the neurons expressing VSFP showed detectable fluorescence signal in response to action potentials (APs). The average signal-to-noise ratio (SNR) obtained in response to five spikes (at 10 Hz) was small (1.3 ± 0.21), however the rapid kinetics of the VSFP allowed discrimination of APs as individual peaks, with detection of 53% of the evoked APs. Frequencies below 5 Hz and subthreshold signals were undetectable due to high noise. On the other hand, calcium indicators showed the greatest change in fluorescence following the same protocol (five APs at 10 Hz). Among the GCaMP3 expressing neurons, 80% (8/10) exhibited signal, with an average SNR value of 21 ±6.69 (soma), while for the R-GECO1 neurons, 50% (2/4) of the neurons had signal, with a mean SNR value of 52 ±19.7 (soma). For protocols at 10 Hz, 54% of the evoked APs were detected with GCaMP3 and 85% with R-GECO1. APs were detectable in all the analyzed frequencies and fluorescence signals were detected from subthreshold depolarizations as well. Because GCaMP3 is the most likely to yield fluorescence signal and with high SNR, some experiments were performed only with this probe. We demonstrate that GCaMP3 is effective in detecting synaptic inputs (involving Ca2+ influx), with high spatial and temporal resolution. Differences were also observed between the SNR values resulting from evoked APs, compared to spontaneous APs. In recordings of groups of cells, GCaMP3 showed clear discrimination between activated and silent cells, and reveals itself as a potential tool in studies of neuronal synchronization. Thus, our results indicate that the presently available calcium indicators allow detailed studies on neuronal communication, ranging from individual dendritic spines to the investigation of events of synchrony in neuronal networks genetically defined. In contrast, studies employing VSFPs represent a promising technology for monitoring neural activity and, although still to be improved, they may become more appropriate than calcium indicators, since neurons work on a time scale faster than events of calcium may foresee

Encoding mechanisms based on fast oscillations in the retina of the cat and their dependencies on anesthesia

Processing in the visual system starts in the retina. Its complex network of cells with different properties enables for parallel encoding and transmission of visual information to the lateral geniculate nucleus (LGN) and to the cortex. In the retina, it has been shown that responses are often accompanied by fast synchronous oscillations (30 - 90 Hz) in a stimulus-dependent manner. Studies in the frog, rabbit, cat and monkey, have shown strong oscillatory responses to large stimuli which probably encode global stimulus properties, such as size and continuity (Neuenschwander and Singer, 1996; Ishikane et al., 2005). Moreover, simultaneous recordings from different levels in the visual system have demonstrated that the oscillatory patterning of retinal ganglion cell responses are transmitted to the cortex via the LGN (Castelo-Branco et al., 1998). Overall these results suggest that feedforward synchronous oscillations contribute to visual encoding. In the present study on the LGN of the anesthetized cat, we further investigate the role of retinal oscillations in visual processing by applying complex stimuli, such as natural visual scenes, light spots of varying size and contrast, and flickering checkerboards. This is a necessary step for understanding encoding mechanisms in more naturalistic conditions, as currently most data on retinal oscillations have been limited to simple, flashed and stationary stimuli. Correlation analysis of spiking responses confirmed previous results showing that oscillatory responses in the retina (observed here from the LGN responses) largely depend on the size and stationarity of the stimulus. For natural scenes (gray-level and binary movies) oscillations appeared only for brief moments probably when receptive fields were dominated by large continuous, flat-contrast surfaces. Moreover, oscillatory responses to a circle stimulus could be broken with an annular mask indicating that synchronization arises from relatively local interactions among populations of activated cells in the retina. A surprising finding in this study was that retinal oscillations are highly dependent on halothane anesthesia levels. In the absence of halothane, oscillatory activity vanished independent of the characteristics of the stimuli. The same results were obtained for isoflurane, which has similar pharmacological properties. These new and unexpected findings question whether feedfoward oscillations in the early visual system are simply due to an imbalance between excitation and inhibition in the retinal networks generated by the halogenated anesthetics. Further studies in awake behaving animals are necessary to extend these conclusions

Resposta comportamental e hormonal de machos não reprodutores de sagüi, callithrix jacchus, a estímulos sensoriais de filhotes não aparentados

Parental care in mammals is influenced by somatosensory stimuli from infants, such as vocalization and sight and by changes in the hormone levels of caretakers. The aim of this study was to evaluate the behavioral and hormonal responses of twelve non reproductive adult male common marmosets (Callithrix jacchus) to infant cues, vocalization recordings, sight and physical contact with newborn. Six out of twelve males had previous experience in caretaking. In article 1, adult males were exposed to newborn vocalizations for 10 minutes. On control condition no sound was presented. In article 2, males were tested on two conditions: a) Control: an empty acrylic transparent box (test box) was placed in male s cage for 15 minutes, and b) Experimental: males were exposed to newborns into a closed text box for 15 minutes. The cage was kept closed to prevented from tactile, smell and acoustic stimulation by the infant on common marmoset males. In article 3, males were exposed to an open or closed text box, which allowed or not their access to and social interaction with the infants. After each observation sessions, blood samples were collected to evaluate the cortisol levels of males. In all studies, behavioral response of adult males was significantly modified by newborns sight, vocalization and physical contact. Males approached and spent more time near the sound source and showed an increase in locomotion during sound exposure. Furthermore, males approached, smelled and spent more time near the test box when the newborn was inside it. There was no difference in behavioral pattern between experienced and non-experienced males in articles 1 and 2. In article 3, behavioral pattern of males was influence by previous caretaking experience. Experienced males recovered quicker and carried the infants more than the inexperienced ones. However, inexperienced males showed a decrease in recovery latency and an increase in carrying time after successive exposure to infants. Cortisol levels changed after exposure to infant s vocalization, especially for experienced adult males. Male hormonal profile was not affected by the sight of infants neither by their previous experienced in caretaking. The occurrence of social interaction between the caretaker and infant did not modify the hormonal profile of common marmoset males; however, as much as experienced males carried the infants their cortisol levels decreased. Thus, members of a social group or potential caretakers common marmosets exposed to sensory cues from dependent infant such as vocalization, sight, smell and physical contact, changed their behavioral and hormonal responses that are physiological modulators of parental behavior in common marmoset