A Model of Stimulus-Specific Neural Assemblies in the Insect Antennal Lobe

It has been proposed that synchronized neural assemblies in the antennal lobe of insects encode the identity of olfactory stimuli. In response to an odor, some projection neurons exhibit synchronous firing, phase-locked to the oscillations of the field potential, whereas others do not. Experimental data indicate that neural synchronization and field oscillations are induced by fast GABAA-type inhibition, but it remains unclear how desynchronization occurs. We hypothesize that slow inhibition plays a key role in desynchronizing projection neurons. Because synaptic noise is believed to be the dominant factor that limits neuronal reliability, we consider a computational model of the antennal lobe in which a population of oscillatory neurons interact through unreliable GABAA and GABAB inhibitory synapses. From theoretical analysis and extensive computer simulations, we show that transmission failures at slow GABAB synapses make the neural response unpredictable. Depending on the balance between GABAA and GABAB inputs, particular neurons may either synchronize or desynchronize. These findings suggest a wiring scheme that triggers stimulus-specific synchronized assemblies. Inhibitory connections are set by Hebbian learning and selectively activated by stimulus patterns to form a spiking associative memory whose storage capacity is comparable to that of classical binary-coded models. We conclude that fast inhibition acts in concert with slow inhibition to reformat the glomerular input into odor-specific synchronized neural assemblies

Finding optimal stimuli ensemble of a cortical network

We explore the determination of the optimal stimuli ensemble of a cortical network on the basis of numerical simulations of a local recurrent network. The optimal stimulus ensemble is determined with the Blahut-Arimoto algorithm using indices of population activity (multiunit activity and local field potentials). We show that the optimal stimulus ensemble is characterized by a distribution where the stimulus which induces a change in the dynamics of the network is highly represented. These results suggests that bifurcation points in the networks dynamic are highly informative and were in accordance with preliminary observation of electrophysiological recordings

Opposite role of slow and fast GABAergic inhibition in synchronization and spike timing precision

International audienc

Modelización como proceso básico en la resolución de problemas contextualizados: un análisis de necesidades

Este trabajo explora las necesidades formativas del alumnado de primer curso del grado en Educación Primaria en el ámbito de la modelización matemática y la resolución de problemas contextualizados. Se ha puesto el foco en el análisis de las estrategias seguidas por el alumnado para abordar un problema, así como en la detección de los errores cometidos; todo ello con el objeto de diagnosticar las necesidades de formación y elaborar un perfil del alumnado que permita adaptar su instrucción a su conocimiento. Los resultados ponen de manifiesto la necesidad de trabajar estrategias para resolver problemas, el pensamiento visual y el manejo de unidades de medida

Information Content in Cortical Spike Trains during Brain State Transitions

Summary Even in the absence of external stimuli there is ongoing activity in the cerebral cortex as a result of recurrent connectivity. This paper attempts to characterize one aspect of this ongoing activity by examining how the information content carried by specific neurons varies as a function of brain state. We recorded from rats chronically implanted with tetrodes in the primary visual cortex during awake and sleep periods. Electro‐encephalogram and spike trains were recorded during 30‐min periods, and 2-4 neuronal spikes were isolated per tetrode off‐line. All the activity included in the analysis was spontaneous, being recorded from the visual cortex in the absence of visual stimuli. The brain state was determined through a combination of behavior evaluation, electroencephalogram and electromyogram analysis. Information in the spike trains was determined by using Lempel-Ziv Complexity. Complexity was used to estimate the entropy of neural discharges and thus the information content (Amigóet al. Neural Comput., 2004, 16: 717-736). The information content in spike trains (range 4-70 bits s−1) was evaluated during different brain states and particularly during the transition periods. Transitions toward states of deeper sleep coincided with a decrease of information, while transitions to the awake state resulted in an increase in information. Changes in both directions were of the same magnitude, about 30%. Information in spike trains showed a high temporal correlation between neurons, reinforcing the idea of the impact of the brain state in the information content of spike trains

Competencia matemática del alumnado de grado de educación primaria: un análisis de necesidades

Este trabajo explora las necesidades formativas en Matemáticas del alumnado de nuevo ingreso en el grado de Educación Primaria. Estos estudiantes, de procedencia heterogénea, suelen presentar un rendimiento irregular en Matemáticas, acompañado de baja autoestima hacia la materia y de una concepción meramente instrumental de la misma. Presentamos un análisis exploratorio del grado de competencia matemática que demuestran nuestros alumnos. Partiendo de la concepción de competencia matemática de PISA (OECD, 2013a), se han seleccionado diferentes ítems liberados que cubren los distintos contenidos del currículo de Educación Primaria, así como los procesos y capacidades PISA. Las respuestas a esos ítems que proporciona el alumnado de primer año de grado de Educación Primaria permiten trazar un perfil de sus necesidades formativas. Dicho perfil nos proporciona la información necesaria para afrontar la formación matemática de los estudiantes noveles de magisterio desde su propio conocimiento

Comment les enseignements interdisciplinaires peuvent-ils motiver l’apprentissage des Mathématiques ?

Math teachers are often confronted with student’s fear or disinterest toward mathematics. We aim to demonstrate to the students that mathematics are understandable by anyone. The different activities set up during our classes brought together mathematics and different subjects (as physics, art, literature or civics) in order to assess how the contextualization of mathematics can affect student’s motivation to learn. The analysis of the students reactions to those activities enabled us to highlight the fact that interdisciplinary teaching, by placing mathematical concepts within everyday life situations, can increase the motivation and educational success of students while arousing their interest in various subjects.Un problème que les enseignants de mathématiques rencontrent dans leurs classes est le désintérêt ou la peur de la part des élèves envers les mathématiques. Nous voulons montrer aux élèves que les mathématiques sont accessibles à tous. Les différentes activités mises en place dans nos classes de sixièmes, cinquièmes et secondes, mettent en relation les mathématiques et d’autres disciplines (comme la physique, l’art, le français ou l’éducation civique), afin d’estimer dans quelle mesure la contextualisation des mathématiques permet de motiver leur apprentissage par les élèves. L’analyse des réactions des élèves à ces activités, nous a permis de mettre en évidence le fait qu’un enseignement interdisciplinaire, en replaçant les concepts mathématiques dans des situations de la vie réelle, peut permettre d’augmenter la motivation et la réussite éducative des élèves, tout en éveillant leur curiosité pour des disciplines variées