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.

Trajetória profissional e rupturas epistemológicas na educação física e na atuação do professor

This dissertation is the result of concerns with the theoretical-methodological and pedagogical learning processes occurred in the practice of physical education in school, which accompany me since the initial training, when I experienced learning in a piecemeal fashion, focused on technicality and sportivization. In order to better qualify the pedagogical interventions of physical education in school, I have always been worried on applying what I received at the University, but the routine of classes was always demanding others doings. In this sense, there were many moments of epistemological ruptures occurred in my training, in which I always sought new investment in training to account for the provision of a more humanistic and grounded in real educational precepts physical education. To that end I had to reflect on the pedagogical interventions throughout my training, in order not to carry out the activities as heavy doings, but as metamorphoses of knowledge and thus generating learning for students. Thus, this dissertation fits into this context with the overall goal of discussing my professional career, considering the epistemological ruptures of Physical Education, occurred in my training and expertise. The objective is also to identify the contributions of these formations in professional activities, centered on storytelling and reflection of significant experiences in the teaching of sports and Physical Education. We highlight the paradigm shifts, leaving the gymnastic methods, through dance-physical education method, psychomotor, reaching the contemporary critical theories experienced from the culture of movement as well as its implications for professional practice. We chose a qualitative research, using the autobiographical method, using as sources or techniques, narratives, photographic recording and video samples. In the studies within the area of education, for the most part, qualitative research came to oppose the positivist view of the quantification on analysis of social phenomena. New ideas were appearing in order to present innovative perspectives to understand the real. The survey data will be presented in narrated form (descriptive), analyzed based on the theoretical framework that guides the study, especially authors who discuss school physical education, vocational training and body conception. We believe our study may be of relevance for training in Physical Education that as from pedagogical reflections in certain historical realities, envisions being able to open new perspectives for the performance of other physical education teachers

Uso de rotas na área de uso e a relação com comportamento alimentar em Callithrix jacchus

Callithrix jacchus are small primates that live in cooperative reproductive family groups. They explore their home range in search of fruits, exudates and animal prey. In this study we investigate the existence of traveling routes and its relation with the feeding habits in a group of Callithrix jacchus. The group was followed for 6 months in an area of Atlantic secondary Forest at the FLONA-ICMBio of Nísia Floresta, Rio Grande do Norte. Two observers in alternated days collected data referring to the group s location using a GPS navigation device, plotting data in 5 minute intervals, and with a position accuracy under 9 meters. All behavioral recordings were done through focal time samplings. The recording windows were 15 minutes with 1 minute intervals. The main activity was foraging, which propelled the animals to explore the environment with inconsistent intensity through the months, and correlated with the location of fruits, exudates and sleeping sites. From another standpoint, most activities were focused in the core areas that featured most sleeping sites, exudates trees and fruit trees. Insects, mostly Orthopterans, were hunted in all areas. The greater ratio of movement was registered during the last hours of sunlight, when animals returned to the sleeping sites and ate a greater number of fruits. The spatial and seasonal distribution of fruits forced the animals to travel long routes. The capacity to remember the location and navigate efficiently through feeding sources is important to save energy and time costs. Learning and familiarizing with the environment through the use of landmarks and acquisition of new information is extremely important to increase the chances of survival in a constantly changing environment