Contrasting roles of axonal (pyramidal cell) and dendritic (interneuron) electrical coupling in the generation of neuronal network oscillations

Electrical coupling between pyramidal cell axons, and between interneuron dendrites, have both been described in the hippocampus. What are the functional roles of the two types of coupling? Interneuron gap junctions enhance synchrony of γ oscillations (25-70 Hz) in isolated interneuron networks and also in networks containing both interneurons and principal cells, as shown in mice with a knockout of the neuronal (primarily interneuronal) connexin36. We have recently shown that pharmacological gap junction blockade abolishes kainate-induced γ oscillations in connexin36 knockout mice; without such gap junction blockade, γ oscillations do occur in the knockout mice, albeit at reduced power compared with wild-type mice. As interneuronal dendritic electrical coupling is almost absent in the knockout mice, these pharmacological data indicate a role of axonal electrical coupling in generating the γ oscillations. We construct a network model of an experimental γ oscillation, known to be regulated by both types of electrical coupling. In our model, axonal electrical coupling is required for the γ oscillation to occur at all; interneuron dendritic gap junctions exert a modulatory effect

Note on Gauge Theory on Fuzzy Supersphere

We construct a supermatrix model whose classical background gives two-dimensional noncommutative supersphere. Quantum fluctuations around it give the supersymmetric gauge theories on the fuzzy supersphere constructed by Klimcik. This model has a parameter $\beta$ which can tune masses of the particles in the model and interpolate various supersymmetric gauge theories on sphere.Comment: 13 pages, LaTe

Employing ternary fission of 242^{242}Pu as a probe of very neutron rich matter

Detailed assessments of the ability of recent theoretical approaches to modeling existing experimental data for ternary fission confirm earlier indications that the dominant mode of cluster formation in ternary fission is clusterization in very neutron rich, very low density, essentially chemically equilibrated, nucleonic matter. An extended study and comparison of these approaches applied to ternary fission yields in the thermal neutron induced reaction $^{241}$Pu($n_{\rm th}$,f) has been undertaken to refine the characterization of the source matter. The resonance gas approximation has been improved taking in-medium effects on the binding energies into account. A temperature of 1.29 MeV, density of $6.7 \times 10^{-5}$ nucleons/fm$^3$ and proton fraction $Y_p$ = 0.035 are found to provide a good representation of yields of the ternary emitted light particles and clusters. In particular, results for $Z= 1$ and 2 isotopes are presented. Isotopes with larger $Z$ are discussed, and the roles of medium and continuum effects, even at very low density are illustrated.Comment: 19 pages, 5 figure

Porque comemos o que comemos?: determinantes psicossociais da selecção alimentar

Este artigo apresenta uma breve análise sobre os determinantes psicossociais do comportamento alimentar. É essencial compreendermos os factores subjacentes às escolhas alimentares dos indivíduos, isto é, compreendermos porque é que comemos os alimentos que comemos e porque comemos a quantidade de alimentos que comemos, se pretendemos intervir neste domínio, seja ao nível da promoção da saúde, seja ao nível da prevenção ou tratamento da doença. No presente trabalho, apresenta-se uma análise sobre alguns dos determinantes psicológicos e sociais da regulação do comportamento alimentar, bem como uma síntese de alguns dos modelos explicativos da selecção alimentar (Modelo Desenvolvimental e Modelo Cognitivo). Procedemos, ainda, a uma reflexão sobre a relação entre alimentos, emoções, cognições e comportamentos, assim como a uma reflexão sobre a relação entre o stress e o comportamento alimentar. ------ ABSTRACT ------ This paper presents a brief analysis of the psychosocial determinants of eating behaviour. It is essential to understand the factors underlying food selection, that is to say, the factors that contribute to the individual eating, what he/she eats and how much he/she eats. In this paper, we present an analysis of some of the psychological and social factors which regulate eating behaviour, as well as some of the theoretical models that try to explain eating behaviour regulation (namely the Developmental Model and the Cognitive Model). We also discuss some issues concerning the relation between food, emotion, cognition and behaviour, and the relation between stress and eating behaviour