An investigation of Hebbian phase sequences as assembly graphs

Hebb proposed that synapses between neurons that fire synchronously are strengthened, forming cell assemblies and phase sequences. The former, on a shorter scale, are ensembles of synchronized cells that function transiently as a closed processing system; the latter, on a larger scale, correspond to the sequential activation of cell assemblies able to represent percepts and behaviors. Nowadays, the recording of large neuronal populations allows for the detection of multiple cell assemblies. Within Hebb's theory, the next logical step is the analysis of phase sequences. Here we detected phase sequences as consecutive assembly activation patterns, and then analyzed their graph attributes in relation to behavior. We investigated action potentials recorded from the adult rat hippocampus and neocortex before, during and after novel object exploration (experimental periods). Within assembly graphs, each assembly corresponded to a node, and each edge corresponded to the temporal sequence of consecutive node activations. The sum of all assembly activations was proportional to firing rates, but the activity of individual assemblies was not. Assembly repertoire was stable across experimental periods, suggesting that novel experience does not create new assemblies in the adult rat. Assembly graph attributes, on the other hand, varied significantly across behavioral states and experimental periods, and were separable enough to correctly classify experimental periods (Naïve Bayes classifier; maximum AUROCs ranging from 0.55 to 0.99) and behavioral states (waking, slow wave sleep, and rapid eye movement sleep; maximum AUROCs ranging from 0.64 to 0.98). Our findings agree with Hebb's view that assemblies correspond to primitive building blocks of representation, nearly unchanged in the adult, while phase sequences are labile across behavioral states and change after novel experience. The results are compatible with a role for phase sequences in behavior and cognition.

Utilização de um ambiente virtual de aprendizagem: um estudo na perspectiva da prática docente

Advances related to information technology are visible and inherent to the management of contemporary organizations, regardless of industrial action. Synchronized with this dynamic, educational institutions are incorporating technological tools that assist its management and academic support to teachers in teaching and interaction with the students. Given that technological innovations are not always taken homogeneously and with the same degree of coverage, remain current and relevant studies on how these technologies are being used in academia. The objective of this research is to identify the usage profile of the functionality of a virtual learning environment related to teaching (undergraduate or postgraduate), demographic variables (age and gender) and institutional (time of admission and academic center of origin.) The methodology applied to the study is descriptive and quantitative. The research is characterized as census, covering all 2152 teachers of undergraduate and graduate students of the Federal University of Rio Grande do Norte, Brazil, who accessed the virtual classes of the Integrated Management of Academic Activities. The study findings revealed that there is a statistically significant difference regarding the use of these tools to teachers who work with undergraduate (49.3%) compared to graduate (6.6%). Regarding gender, women (40.1%) use the system more than men (38.5%). It was also observed that the younger teachers, aged 37 years, are the most active users (42.5%) of the Virtual Class with respect to their elders. For teachers with up to three years time of admission to the UFRN, the pattern of use is more advanced than those with more seniority, as well as the faculty of the Center for Science and Technology are the least likely to use the tools available in relation to other academic centers. It is hoped that with this study managers can direct actions to improve and expand the use of this environment by teachers

Arquitetura residencial em João Pessoa-PB a experiência moderna nos anos 1970

In the mid-1980s, the magazine Projeto published the Actual Brazilian Architecture catalogue presenting texts by Hugo Segawa and Ruth Verde Zein with a corpus of works and engaged architects of the 1960s and 1970s. To comprehend the Brazilian architectural production post-1964, in those years of the 1980s, became a significant mission to reactivate the Brazilian architectural debate weakened by the military dictatorship. In his doctoral thesis Spadoni (2003) deals with the different ways which characterizes the Brazilian architectural production of the 1970s. Marked by inventiveness, this production was in tune with the modern thinking and in the transition period between the 1970s and the 1980s it synchronized with the international debate about post-modern architecture. Considering Spadoni s doctoral thesis, this work deals with the modern experience observed in the one-family-houses built in the seventies in João Pessoa. Some modern experiences were not clear outside, to observe it, it was necessary to search for the type of experience into the spatial disposition and of the know-how constructive, because into the appearance some houses not make explicit the use of the modern language. Other observed experiences allude to the repertoire of the Brazilian period in the years 1940s-1960s, to the experience of the modern architecture in São Paulo of the 1960s, to the experiences in which the climate of the Northeastern region strongly influenced the architectural conception. We can also find in a reduced number of houses a particular experience: it refers to experiences that expose the constructive doing, which leave the material apparent and apply to the residential type the experience of the industrial pre-fabricated buildings