Neuronal adaptation effects in decision making

Recently, there has been an increased interest on the neural mechanisms underlying perceptual decision making. However, the effect of neuronal adaptation in this context has not yet been studied. We begin our study by investigating how adaptation can bias perceptual decisions. We considered behavioral data from an experiment on high-level adaptation-related aftereffects in a perceptual decision task with ambiguous stimuli on humans. To understand the driving force behind the perceptual decision process, a biologically inspired cortical network model was used. Two theoretical scenarios arose for explaining the perceptual switch from the category of the adaptor stimulus to the opposite, nonadapted one. One is noise-driven transition due to the probabilistic spike times of neurons and the other is adaptation-driven transition due to afterhyperpolarization currents. With increasing levels of neural adaptation, the system shifts from a noise-driven to an adaptation-driven modus. The behavioral results show that the underlying model is not just a bistable model, as usual in the decision-making modeling literature, but that neuronal adaptation is high and therefore the working point of the model is in the oscillatory regime. Using the same model parameters, we studied the effect of neural adaptation in a perceptual decision-making task where the same ambiguous stimulus was presented with and without a preceding adaptor stimulus. We find that for different levels of sensory evidence favoring one of the two interpretations of the ambiguous stimulus, higher levels of neural adaptation lead to quicker decisions contributing to a speed–accuracy trade off.

The neuronal basis of attention: rate versus synchronization modulation

Extensive theoretical and experimental work on the neuronal correlates of visual attention raises two hypotheses about the underlying mechanisms. The first hypothesis, named biased competition, originates from experimental single-cell recordings that have shown that attention upmodulates the firing rates of the neurons encoding the attended features and downregulates the firing rates of the neurons encoding the unattended features. Furthermore, attentional modulation of firing rates increases along the visual pathway. The other, newer hypothesis assigns synchronization a crucial role in the attentional process. It stems from experiments that have shown that attention modulates gamma-frequency synchronization. In this paper, we study the coexistence of the two phenomena using a theoretical framework. We find that the two effects can vary independently of each other and across layers. Therefore, the two phenomena are not concomitant. However, we show that there is an advantage in the processing of information if rate modulation is accompanied by gamma modulation, namely that reaction times are shorter, implying behavioral relevance for gamma synchronization.

Eventos adversos em Unidade de Terapia Intensiva: percepção dos enfermeiros sobre a cultura não punitiva

A cultura de segurança nas unidades de terapia intensiva (UTI) pressupõe a abordagem não-punitiva dos eventos adversos (EA), porém questiona-se a sua existência segundo a percepção dos enfermeiros. Foram objetivos do estudo: caracterizar os sistemas de notificação de EA; verificar a freqüência dos eventos e conseqüências para os profissionais; verificar o grau de segurança dos enfermeiros para notificá-los. Estudo descritivo, com questionário respondido por 70 enfermeiros, em 2007, seguido da análise descritiva dos dados. A maioria dos enfermeiros (70,0%) referiu-se à existência de um sistema de notificação de EA nas instituições onde atuam. A ocorrência de EA algumas e várias vezes foram citadas por 51,4% e 28,6% dos enfermeiros, respectivamente. Para 74,3% da amostra, a punição ocorre às vezes e sempre, predominando a advertência verbal (49,0%). A maioria (74,3%) referiu sentir-se seguro e totalmente seguro para notificar um EA. Conclui-se que a cultura punitiva ainda persiste nas UTIs.

IKEA- Una compañía multinacional en la época de la globalización. La influencia de la cultura en la comunicación publicitaria

El fenómeno de la globalización es cada vez más presente en la vida cotidiana. Juntocon este proceso, se han desarrollado las compañías multinacionales. El reto de estas compañías es de sobrevivir en medios distintos y de adaptarse a cada público, que tiene sus especificidades.Las estrategias de comunicación se crean conforme con las exigencias de cada mercado local.¿Cuál es el papel de la cultura en el proceso de creación de las campañas de comunicación de las compañías multinacionales? ¿Qué indicios nos dan los eslóganes publicitarios sobre la relaciónque se establece entre la identidad del producto y las influencias culturales

The contribution of patch topology and demographic parameters to PVA predictions: the case of the European tree frog

Population viability analyses (PVA) are increasingly used in metapopulation conservation plans. Two major types of models are commonly used to assess vulnerability and to rank management options: population-based stochastic simulation models (PSM such as RAMAS or VORTEX) and stochastic patch occupancy models (SPOM). While the first set of models relies on explicit intrapatch dynamics and interpatch dispersal to predict population levels in space and time, the latter is based on spatially explicit metapopulation theory where the probability of patch occupation is predicted given the patch area and isolation (patch topology). We applied both approaches to a European tree frog (Hyla arborea) metapopulation in western Switzerland in order to evaluate the concordances of both models and their applications to conservation. Although some quantitative discrepancies appeared in terms of network occupancy and equilibrium population size, the two approaches were largely concordant regarding the ranking of patch values and sensitivities to parameters, which is encouraging given the differences in the underlying paradigms and input data.

Development of neuronal markers in aggregating fetal rat telencephalon cells cultured in the presence of triiodothyronine.

The concentrations of the general neuronal markers D2-protein (N-CAM), D3-protein and neuron specific enolase (NSE) in reaggregating cultures of fetal rat telencephalon cells were affected by the presence of 30 nM triiodothyronine in the defined culture medium. The extent of normal developmental changes were enhanced by triiodothyronine, as demonstrated by crossed immunoelectrophoresis. From 13 to 19 days in culture, the concentration of D2-protein decreased, and the concentrations of both D3-protein and NSE increased. Nerve growth factor (NGF) was without effect on the development of these general neuronal markers. However, as shown previously both triiodothyronine and NGF increased the activity of choline acetyltransferase, a marker for cholinergic neurons. The results suggest an enhanced overall differentiation of several types of telencephalon neurons in the presence of triiodothyronine, and a specific stimulation of cholinergic telencephalon neurons by NGF.

Tradução e adaptação para a cultura brasileira do Gaudenz-Fragebogen

O artigo visa descrever o processo de tradução e adaptação para a cultura brasileira do Gaudenz-Fragebogen, instrumento de origem alemã, utilizado no diagnóstico da incontinência urinária feminina. Seguiram-se, nesse intuito, as etapas recomendadas pela literatura internacional: tradução, síntese das traduções, retrotradução, avaliação pelo comitê de especialistas e pré-teste. Os processos de tradução e adaptação foram realizados a contento e o instrumento demonstrou ser de fácil compreensão. Entretanto, este é um estudo que antecede o processo de validação e será premente o emprego do instrumento em novas pesquisas para que sejam avaliadas suas propriedades de medida.