KeywordsOs processos que levam à seleção de certas categorias de informação para processamento preferencial, que caracterizam a atenção, dependem não apenas da história prévia do sistema selecionador, isto é, suas memórias, como também de expectativas geradas com base em memórias sobre regularidades passadas e planos de ação. Defende-se neste trabalho que a associação conceitual envolvendo memória e atenção é vantajosa pois permite oferecer explicações parcimoniosas sobre diversos fenômeros revelados em estudos sobre atenção, além de gerar previsões testáveis sobre os efeitos da experiência prévia no desempenho em testes de atenção. Apresenta-se aqui um modelo sobre a influência de memórias (representadas por vias facilitadas no sistema nervoso) na atividade da rede nervosa e nos processos atencionais durante o desempenho de determinados tipos de tarefas. IntroduçãoMemória corresponde ao processo pelo qual experiências anteriores levam à alteração do comportamento. Atenção corresponde a um conjunto de processos que leva à seleção ou priorização no processamento de certas categorias de informação; isto é, "atenção" é o termo que refere-se aos mecanismos pelos quais se dá tal seleção.O sistema nervoso, em seu processo histórico de interação inicial com o ambiente, reage não apenas a estímulos, mas também às contingências espaciais e temporais entre os estímulos, e também destes com suas respostas, num processo de aprendizagem que leva a modificações no seu funcionamento, caracterizando alterações "de-baixo-para-cima". Com o acúmulo desses registros sobre ocorrências anteriores -memórias no sentido amplo da palavra -e a identificação de regularidades na ocorrên-cia desses eventos, o sistema nervoso passa a gerar previsões (probabilísticas) sobre o ambiente. Então, passa a agir antecipatoriamente e a selecionar as informações que serão processadas -um processo de "cima-para-baixo" -o que confere grande vantagem adaptativa. 1 Uma das conseqüências desse processo é o desenvolvimento de intencionalidade; ou seja, como resultados almejados podem ser previstos com base em registros sobre regularidades passadas, o sistema nervoso pode (1) gerar ações que levem aos resultados desejados e (2) atuar no sentido de selecionar determinados tipos de informação para processamento adicional, isto é, direcionar sua atenção.É indiscutível que esse processo de seleção atencional depende não apenas da história prévia do sistema selecionador, envolvendo suas memórias e portanto o significado pessoal e emocional dos estímulos, mas também de expectativas geradas
In the near future, Brazil is expected to face a number of challenges with regards to economic and social development, and scientific production is a critical aspect of this development process. Over the past 30 years, there has been an almost 18-fold increase in the number of brazilian papers published, up from about 2,000 in 1980 to more than 35,000 in 2009. In this study we analyze the evolution of scientific production in terms of input (resources and permanent investigators) and output (scientific papers and doctorate graduates). We evaluate whether structural investments and the number of investigators at universities are both able to explain the increase in the number of papers, by investigating the relationships among growth rates in investments and the quantity of the papers published, as well as the number of doctorate graduates and active permanent investigators. As an indication of the fluctuations in investments pertaining to academic research, we consider the budget history of the largest Brazilian federal agencies charged with providing academic grants. We observe that the burgeoning number of papers has occurred independently of investments and the number of established investigators, thus suggesting an increase in the efficiency of Brazilian scientific output. Moreover, this increase in efficiency has occurred in conjunction with an increased number of Doctoral graduates per year. In this context, we propose that an evaluation of the academic structure is necessary in order to ascertain the risks of this increased ''efficiency''. Moreover, the recent cut of over US$ 1 billion announced by the Brazilian government may jeopardize the quality of scientific output in the future.
The trails formed by many ant species between nest and food source are two-way roads on which outgoing and returning workers meet and touch each other all along. The way to get back home, after grasping a food load, is to take the same route on which they have arrived from the nest. In many species such trails are chemically marked by pheromones providing orientation cues for the ants to find their way. Other species rely on their vision and use landmarks as cues. We have developed a method to stop foraging ants from shuttling on two-way trails. The only way to forage is to take two separate roads, as they cannot go back on their steps after arriving at the food or at the nest. The condition qualifies as a problem because all their orientation cues – chemical, visual or any other - are disrupted, as all of them cannot but lead the ants back to the route on which they arrived. We have found that workers of the leaf-cutting ant Atta sexdens rubropilosa can solve the problem. They could not only find the alternative way, but also used the unidirectional traffic system to forage effectively. We suggest that their ability is an evolutionary consequence of the need to deal with environmental irregularities that cannot be negotiated by means of excessively stereotyped behavior, and that it is but an example of a widespread phenomenon. We also suggest that our method can be adapted to other species, invertebrate and vertebrate, in the study of orientation, memory, perception, learning and communication.
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