J. Marro, J.J. Torres and J.M. Cortes. Complex behavior in a network with time-dependent connections and silent nodes. Journal of Statistical Mechanics P02017, 2008 [pdf] We studied, both analytically and numerically, excitable networks in which connections are time-dependent and some of the nodes remain silent at each time step, and we show that these two features may induce intriguing functional complexity. More specifically, we consider (a) a heterogeneous distribution of […]
J.M.A.M. Kusters, J.M. Cortes, W.P.M. van Meerwijk, D.L. Ypey, A.P.R. Theuvenet and C.C.A.M. Gielen. Hysteresis and bi-stability by an interplay of calcium oscillations and action potential firing. Physical Review Letters 98: 098107, 2007. Nomination of PRL HighLights in the Magazine The Biological Physicist 7, April 2007 [pdf] Many cells reveal oscillatory behavior. Some cells reveal action-potential firing resulting from Hodgkin-Huxley (HH) type dynamics of ion channels in the cell membrane. […]
J. Marro, J.J. Torres and J.M. Cortes. Networks with Heterogeneously Weighted Connections and Partial Synchronization of Nodes. Computer Physics Communications 177: 180-183, 2007 [pdf] A network of stochastic nodes in which connections are heterogeneously weighted and dynamics may by varied from single-node updating to full synchronization as in familiar cellular automata is studied concerning computational strategies and states of attention in the brain.
J.J. Torres, J. M. Cortes, J. Marro and H.J. Kappen. Attractor Neural Networks with Activity-Dependent Synapses: The Role of Synaptic Facilitation. Neurocomputing 70: 2022-2025, 2007 [pdf] We studied an autoassociative neural network with dynamic synapses which include a facilitating mechanism. We have developed a general mean-field framework to study the relevance of the different parameters defining the dynamics of the synapses and their influence on the collective properties of the […]
J. Marro, J.J. Torres and J.M. Cortes. Chaotic hopping between attractors in neural automata. Neural Networks 20: 230-235, 2007 [pdf] We present a neurobiologically-inspired stochastic cellular automaton whose state jumps with time between the attractors corresponding to a series of stored patterns. The jumping varies from regular to chaotic as the model parameters are modified. The resulting irregular behavior, which mimics the state of attention in which a system shows […]
J.J. Torres, J.M. Cortes, J. Marro and H.J. Kappen. Competition between synaptic depression and facilitation in attractor neural networks. Neural Computation 19: 2739-2755, 2007 [pdf] We study the effect of competition between short-term synaptic depression and facilitation on the dynamic properties of attractor neural networks, using Monte Carlo simulation and a mean-field analysis. Depending on the balance of depression, facilitation, and the underlying noise, the network displays different behaviors, including […]
J. M. Cortes, J. Marro and J. J. Torres. Control of neural chaos by synaptic noise. Biosystems 87: 186-190, 2007 [pdf] We study neural automata or neurobiologically inspired cellular automata which exhibits chaotic itinerancy among the different stored patterns or memories. This is a consequence of activity-dependent synaptic fluctuations, which continuously destabilize the attractor and induce irregular hopping to other possible attractors. The nature of these irregularities depends on the […]
J. M. Cortes, J. J. Torres, J. Marro, P. L. Garrido and H. J. Kappen. Effects of fast presynaptic noise in attractor neural networks. Neural Computation 18: 614-633, 2006 [pdf] We study both analytically and numerically the effect of presynaptic noise on the transmission of information in attractor neural networks. The noise occurs on a very short timescale compared to that for the neuron dynamics and it produces short-time synaptic […]
J. J. Torres, J. Marro, P. L. Garrido, J. M. Cortes, F. Ramos and M. A. Munoz. Effects of static and dynamic disorder on the performance of neural automata. Biophysical Chemistry 115: 285-288, 2005 [pdf] We report on both analytical and numerical results concerning stochastic Hopfield-like neural automata exhibiting the following (biologically inspired) features: (1) Neurons and synapses evolve in time as in contact with respective baths at different temperatures; […]
Sebastiano Stramaglia, Leonardo Angelini, Jesus M. Cortes and Daniele Marinazzo. Synergy, redundancy and unnormalized Granger causality. EMBS 4037-4040, 2015 [arXiv:1504.03584] [pdf]
S. Stramaglia, J.M. Cortes, L. Angelini, M. Pellicoro and D. Marinazzo. Information flow in Ising models on brain networks. V.M. Mladenov and P.C. Ivanov (Eds.): NDES 2014, CCIS 438, pp. 301–308, 2014 [pdf]. We analyze the information flow in the Ising model on two real networks, describing the brain at the mesoscale, with Glauber dynamics. We find that the critical state is characterized by the maximal amount of information flow […]
J. Hidalgo, L.F. Seoane, J.M. Cortes and M.A. Muñoz. Does the phenomenon of stochastic amplification of fluctuations play a relevant role in cortical dynamics? AIP Conference Proceedings 1510: 94-100, 2012 [pdf] We review the mechanism of stochastic amplification of fluctuations in the context of fast cortical oscillations observed during up-states both in vitro and in vivo. For this purpose, we employ minimalistic models based on short-time synaptic depression with or […]
A. Lopez, J.M. Cortes, D. Lopez-Oller, R. Molina and A.K. Katsaggelos. Hyperparameters Estimation for the Bayesian Localization of the EEG Sources with TV Priors. EUSIPCO 2012: 20th European Signal Processing Conference , pags 489-493, 2012 [pdf] In this work we propose a new Bayesian method for the non-invasive localization of EEG sources. For this problem, most of the existing methods assume that the sources are distributed throughout the brain volume […]
J.M. Cortes, D. Marinazzo, T.J. Sejnowski and M.C.W. van Rossum. The Direction of Tilt Aftereffects Depends on Short-term Inhibitory Facilitation. NIPS 2011, Submitted but Rejected [pdf] Neural adaptation leads to changes in the responses of single neurons and neural populations during continued exposure to a stimulus. At the single neuron level, adaptation reduces responses to a constant stimulus. At the perceptual level, adaptation can manifest itself as aftereffects. For instance, […]
J.M. Cortes. Interfaces cerebro-maquina, un gran paso hacia la Inteligencia Artificial. Ciencia Cognitiva: Revista Electronica de Divulgacion 3: 24-26, 2009 [pdf] Dentro de la Neurociencia Computacional, la Neuro-ingeniería desarrolla sistemas de comunicación entre una máquina y alguna parte del sistema nervioso. Sin lugar a dudas, estos sistemas constituyen un gran reto científico, ingenieril y ético. Sin embargo, su correcto funcionamiento todavía plantea muchos problemas.
J.M. Cortes. La Neurociencia Computacional hoy: I. Que es y por que es dificil su estudio. Ciencia Cognitiva: Revista Electronica de Divulgacion 3: 5-7, 2009 [pdf] La Neurociencia Computacional es una disciplina consolidada, con más de 20 años de desarrollo, y que emplea técnicas muy diversas para entender diferentes computaciones cerebrales. Aquí se introduce brevemente mediante dos artículos. En el primero, “Qué es y por qué es difícil su estudio”, […]
J.M. Cortes. La Neurociencia Computacional hoy: II. Un ejemplo muy representativo en el campo. Ciencia Cognitiva: Revista Electronica de Divulgacion 3: 8-11, 2009 [pdf] La Neurociencia Computacional es un campo reciente, pero bien establecido dentro de las Neurociencias. En un primer artículo Cortes 2009, “Qué es y por qué es difícil su estudio”, explico su principal paradigma: todo proceso mental que tiene lugar en nuestro cerebro tiene un circuito o […]
J.M.A.M. Kusters, J.M. Cortes, W.P.M. van Meerwijk, D.L.Ypey, A.P.R. Theuvenet and C.C.A.M. Gielen. Oscillatory activity in cells: multi-stability and hysteresis. AIP Conference Proceedings 887: 40-50, 2007 [pdf] Oscillatory activity of cells has been the topic of many studies. Oscillatory activity can be due to action potential firing corresponding to the well-known Hodgkin-Huxley (HH) type dynamics of ion-channels in the cell membrane or due to IP3-mediated calcium oscillations in the endoplasmic […]
J.J. Torres, J. M. Cortes and J. Marro. Information processing with unstable memories. AIP Conference Proceedings 887: 115-128, 2007 [pdf] We present a theoretical framework which allows one to study both theoretically and numerically the effect of including activity dependent mechanisms in the dynamics of synapses in simple neural networks. In particular, we study synaptic changes at different time scales from less than the millisecond (fast synaptic noise) to the […]
J.M. Cortes, A. Greve and M.C.W. van Rossum. Dynamical effects on familiarity discrimination. AIP Conference Proceedings 887: 217-223, 2007 [pdf] One process involved in recognition memory is familiarity discrimination. Familiarity distinguishes almost immediately after stimulus presentation whether the item was previously encountered (old) or novel. By using a formalism based on attractor neural networks, we discuss different dynamical processes affecting familiarity discrimination. First, we compare two different familiarity discriminators, the […]
J. Marro, J. M. Cortes and J. J. Torres. Discriminacion, generalizacion y clasificacion mediante automatas neuronales con ruido que induce depresion sinaptica. In CEDI2005, Ed. Thomson, pp. 335-341, 2005 ISBN:84-9732-444-7 [pdf] En una serie de trabajos recientes se estudian varias realizaciones de redes de neuronas artificiales que tienen aspectos notables. Se trata de algoritmos que, además de mostrar una memoria asociativa eficaz, son capaces de detectar similitudes (generalización) y diferencias […]
J.M. Cortes. Cooperative Phenomena in Stochastic Neural Networks with Dynamic Synapses. PhD Thesis, 2005. ISBN: 84-3383-291-3 [pdf]
D. Marinazzo, M. Pellicoro, G. Wu, L. Angelini, J.M. Cortes and S. Stramaglia. Information transfer of an Ising model on a brain network. Computational NeuroScience (CNS) 2013 Meeting. BMC Neuroscience 2013, 14(Suppl 1):P376 We consider an anatomical connectivity matrix (66 nodes), obtained via diffusion spectrum imaging (DSI) and white matter tractography [1], describing the brain at a coarse scale, and implement on it an Ising model with Glauber dynamics, estimating […]
A Erramuzpe, GJ Ortega, J Pastor, RG de Sola, D Marinazzo, S Stramaglia and JM Cortes. Redundancy and synergetic circuits in inter-ictal activity of human temporal lobe epilepsy. Society for Neuroscience Annual Meeting 2014. The use of information theory in neuroscience have allowed to evaluate the interaction between groups of correlated variables, revealing their functional role and underlying circuits capable of processing information (Borst and Theunissen, 1999, Nat Neurosci; Panzeri […]
A Erramuzpe, JM Encinas, A Sierra, M Maletic-Savatic, AL Brewster, AE Anderson, S Stramaglia and JM M Cortes. Variations in whole-brain functional connectivity across seizure chronification in a mouse model of mesial temporal lobe epilepsy. Society for Neuroscience Annual Meeting 2014. How does the brain become epileptic? Although this is a major question for modern Neurology, we do not have yet a proper answer. Despite of intense research in the […]
I. Ortega-Martinez, J. Gardeazabal, A. Erramuzpe, R. Fernandez-Suarez, E. Alonso-Tejerina, G. Perez-Yarza, J.M. Cortes, I.M. de la Fuente, A. Asumendi and M.D. Boyano. Serum Proteomics in Melanoma Biomarker Discovery. 13th Annual World Congress of the Human Proteome Organization 2014. Introduction and objectives Patients with early-stage melanoma and no lymph node involvement have a high likelihood of cure after complete excision of the tumor by surgery. However, there is no effective […]
J.M. Cortes, J. Goñi, M.A. Muñoz and D.R. Chialvo. Generic dynamics at criticality links brain structure to function. Frontiers in Neuroinformatics, 2013 [pdf] The relation, influence, and constraints between structure and function of the human brain is not yet well understood, even for the widely studied resting state. In the last decade, different topological descriptors, and dynamical models such as neural mass or more complicated coupling models have shown how […]
V. Maki-Marttunen, J.M. Cortes, M. Villareal and D.R. Chialvo. Disruption of transfer entropy and inter-hemispheric brain functional connectivity in patients with disorder of consciousness. Computational NeuroScience (CNS) 2013 Meeting. BMC Neuroscience 2013, 14(Suppl 1):P83 [pdf] CNS 2013 Best Student Poster Award Winner. Recent studies suggest that the functional organization of brain networks is altered in patients with severe disorders of consciousness (DOC), including coma [1]. A better characterization of these […]
J.M. Cortes, D. Marinazzo, P. Series, M.W. Oram, T.J. Sejnowski and M.C.W. van Rossum. Neural adaptation reduces energy cost while preserving coding accuracy. Society for Neuroscience Annual Meeting 2010 Neurons in the primary visual cortex initially respond vigorously when a preferred stimulus is presented, but typically adapt as stimulation continues. The functional consequences of adaptation are unclear. Typically a reduction of firing reduces single neuron accuracy, but it has been […]
J.M. Cortes, D. Marinazzo, P. Tudela and E. Madrid. Causal connectivity analysis of tracking faces in presence of repeated distractors during working memory tasks. Society for Neuroscience Annual Meeting 2009 Recognition of a specific visual target among equally familiar distracters requires neural mechanisms for tracking items in working memory. High Density EEG recordings were obtained from sixteen right-handed normal participants while they performed a visual working memory task in which […]