Integration of continuous-time dynamics in a spiking neural network simulator

Contemporary modeling approaches to the dynamics of neural networks consider two main classes of models: biologically grounded spiking neurons and functionally inspired rate-based units. The unified simulation framework presented here supports the combination of the two for multi-scale modeling approaches, the quantitative validation of mean-field approaches by spiking network simulations, and an increase in reliability by usage of the same simulation code and the same network model specifications for both model classes. While most efficient spiking simulations rely on the communication of discrete events, rate models require time-continuous interactions between neurons. Exploiting the conceptual similarity to the inclusion of gap junctions in spiking network simulations, we arrive at a reference implementation of instantaneous and delayed interactions between rate-based models in a spiking network simulator. The separation of rate dynamics from the general connection and communication infrastructure ensures flexibility of the framework. We further demonstrate the broad applicability of the framework by considering various examples from the literature ranging from random networks to neural field models. The study provides the prerequisite for interactions between rate-based and spiking models in a joint simulation

Ontologies and Knowledge Aggregation in the Active Semantic Learning System

5 PagesInternational audienceThe construction of semantic-based learning systems depends on the development of ontologies and the capacity to integrate and exploit knowledge using semantic technologies, notably RDF and ontologies. In this paper we present some concepts and ontologies defined in the context of the Active Semantic Learning System (Active SLS) that are used to describe resources and the semantic relation between these concepts defined in different ontologies. The purpose is to obtain a learning system that is capable of aggregating knowledge from different sources from the web and to exploiting that knowledge for the benefit of the learner

On Stability in Control Systems

Stability definitions for generalized control systems - dynamical system

Mean-field equations for stochastic firing-rate neural fields with delays: Derivation and noise-induced transitions

In this manuscript we analyze the collective behavior of mean-field limits of large-scale, spatially extended stochastic neuronal networks with delays. Rigorously, the asymptotic regime of such systems is characterized by a very intricate stochastic delayed integro-differential McKean-Vlasov equation that remain impenetrable, leaving the stochastic collective dynamics of such networks poorly understood. In order to study these macroscopic dynamics, we analyze networks of firing-rate neurons, i.e. with linear intrinsic dynamics and sigmoidal interactions. In that case, we prove that the solution of the mean-field equation is Gaussian, hence characterized by its two first moments, and that these two quantities satisfy a set of coupled delayed integro-differential equations. These equations are similar to usual neural field equations, and incorporate noise levels as a parameter, allowing analysis of noise-induced transitions. We identify through bifurcation analysis several qualitative transitions due to noise in the mean-field limit. In particular, stabilization of spatially homogeneous solutions, synchronized oscillations, bumps, chaotic dynamics, wave or bump splitting are exhibited and arise from static or dynamic Turing-Hopf bifurcations. These surprising phenomena allow further exploring the role of noise in the nervous system.Comment: Updated to the latest version published, and clarified the dependence in space of Brownian motion

Spatiotemporal dynamics on small-world neuronal networks: The roles of two types of time-delayed coupling

We investigate temporal coherence and spatial synchronization on small-world networks consisting of noisy Terman-Wang (TW) excitable neurons in dependence on two types of time-delayed coupling: $\{x_j(t-\tau)-x_i (t)\}$ and $\{x_j(t-\tau)-x_i(t-\tau)\}$. For the former case, we show that time delay in the coupling can dramatically enhance temporal coherence and spatial synchrony of the noise-induced spike trains. In addition, if the delay time $\tau$ is tuned to nearly match the intrinsic spike period of the neuronal network, the system dynamics reaches a most ordered state, which is both periodic in time and nearly synchronized in space, demonstrating an interesting resonance phenomenon with delay. For the latter case, however, we can not achieve a similar spatiotemporal ordered state, but the neuronal dynamics exhibits interesting synchronization transition with time delay from zigzag fronts of excitations to dynamic clustering anti-phase synchronization (APS), and further to clustered chimera states which have spatially distributed anti-phase coherence separated by incoherence. Furthermore, we also show how these findings are influenced by the change of the noise intensity and the rewiring probability. Finally, qualitative analysis is given to illustrate the numerical results.Comment: 17 pages, 9 figure

Recensión del Libro de ROXIN, Claus, Derecho penal, Parte General, tomo II, Especiales formas de aparición del delito, Traducción y notas de Diego-Manuel Luzón Peña (Director), José Manuel Paredes Castañón, Miguel Díaz y García Conlledo, Javier de Vicente Remesal, en colaboración con otros, Editorial Civitas/Thomson Reuters, 2014, 1069 páginas.

A estas alturas no es necesario destacar la importancia de la obra de Roxin y la influencia que la misma ha ejercido en la Ciencia del Derecho penal en los últimos sesenta años no sólo en Alemania, sino en otros muchos países, especialmente en los de lengua española, tanto en España, como en todos los países latinoamericanos, incluyendo también a Brasil, en los que ha impartido innumerables conferencias, participado en diversos Congresos y recibido ya veinticinco doctorados honoris causa. Muchos son también los penalistas hispano parlantes que han estudiado directamente con él desde que se trasladó a la Universidad de Munich a principios de los años setenta del pasado siglo, después de unos años como Profesor en la Universidad de Gotinga. Innumerable es además el número de penalistas que indirectamente a través de sus trabajos, artículos, libros y monografías, traducidos al español, han adquirido o profundizado sus conocimientos de Derecho penal a través de la obra de Claus Roxin

Trying Cases in the Media: A Comparative Overview

The essay deals with the problem of media impact on ongoing trials. In particular, it proposes a taxonomy of three comparative models of governance (traditional common law approach; US approach; Continental European approach) and makes a case for the recognition of presumption of innocence as a fundamental rigth vis-à-vis the court of public opinion

Coordonatele auditului in marketingul financiar-bancar - situatia din Romania

The general term of internal audit was established in relation to the financial accounting activity; this notion was gradually replaced by a new approach which expands the sphere of the audit so that the preoccupation for the future is very important for any audit activity. If forming and consolidating a favorable image of the bank among service consumers represents a marketing problem, then solving it requires numerous instruments from the marketing policies; the most important role is attributed to the audit. The final goal of the marketing audit is drawing up a table regarding the performances and the efficiency of the bank, in relation to the risks involved by financial institutions and its operations. In this respect, specialists in banking management have come up with different models of calculations and rating systems in their trials to obtain the most accurate scan of the “state of health” of the banks, and moreover in their trials to identify the institutions which face financial and operational difficulties leading to bankruptcy. The uniform bank rating system is a specific instrument for the supervising activity and has its origins in the USA ; it has later been borrowed by German, Italian, Great Britain authorities, which use influential components in their banking system; later on, their system was adopted by most central banks within the European Union. In Romania, the uniform bank rating system has been implemented by N.B.R. (the National Bank of Romania) since 2000; the specific components that were analyzed are: the capital adequacy (C), the quality of assets (A), the management (M), profitability (P), liquidities (L) and sensitivity (S) starting from the year 2005. For short, this system is called CAMPL. The evaluation of these specific elements represents an important criterion for establishing a compound rating, which means assigning scores to each bank. The compound rating for the banking system is established based on economic – financial indicators and prudence indicators.marketing audit; uniform bank rating system; the capital adequacy; the quality of assets ; sensitivity to market risk