Search results for "neurones"
showing 10 items of 25 documents
The effect of neurodegenerative lesions on the mechanism of motor resonance induced by action observation
2018
The concept of “embodied cognition” considers that the classical Perception-Cognition-Action architecture proposing a sequential flow of processing with clean cuts between all modules is not appropriate to understand the behavioral effect of neurodegenerative disorders and to find innovative therapeutic solutions. In the last decades, the discovery of the mirror neurons (MN) has given a biological substrate to this theoretical perspective: the MN are now thought linking together knowledge about actions and perceptions not only to integrate perception in action planning and execution but also as a neural mechanism supporting a wide range of cognitive functions, e.g. empathy and language. At …
The generation of oligodendroglial cells is preserved in the rostral migratory stream during aging
2013
The subventricular zone (SVZ) is the largest source of newly generated cells in the adult mammalian brain. SVZ-derived neuroblasts migrate via the rostral migratory stream (RMS) to the olfactory bulb (OB), where they differentiate into mature neurons. Additionally, a small proportion of SVZ-derived cells contribute to the generation of myelinating oligodendrocytes. The production of new cells in the SVZ decreases during aging, affecting the incorporation of new neurons into the OB. However, the age-related changes that occur across the RMS are not fully understood. In this study we evaluate how aging affects the cellular organization of migrating neuroblast chains, the proliferation, and th…
Classification of spectra and search for biomarkers in prostate tumours from proton nuclear magnetic resonance spectroscopy
2010
Prostate cancer is the most common cancer in men over 50 years. Current detection methods either lack sensitivity or specificity or are unpleasant for the patient. Magnetic resonance spectroscopy allows the study of metabolism in vivo. The use of a high field machine (≥3T) has allowed us to dispense with the use of an endorectal coil, which is particularly uncomfortable for the patient. The objective of this thesis is to create an automatic method to detect cancer by processing data obtained through magnetic resonance spectroscopy MRS is a complex phenomenon, very sensitive to acquisition conditions. Firstly, we have studied how to improve and optimise signal acquisition. However, even with…
Research and implementation of artificial neural networks models for high velocity oxygen fuel thermal spraying
2020
In the high velocity oxygen fuel (HVOF) spray process, the coating properties are sensitive to the characteristics of in-flight particles, which are mainly determined by the process parameters. Due to the complex chemical and thermodynamic reactions during the deposition procedure, obtaining a comprehensive multi-physical model or analytical analysis of the HVOF process is still a challenging issue. This study proposes to develop a robust methodology via artificial neural networks (ANN) to solve this problem for the HVOF sprayed NiCr-Cr3C2 coatings under different operating parameters.First, 40 sets of HVOF spray experiments were conducted and the coating properties were tested for analysis…
Optimisation et implémentation de méthodes bio-inspirées d'extraction de caractéristiques pour la reconnaissance d'objets visuels
2016
Industry has growing needs for so-called “intelligent systems”, capable of not only ac-quire data, but also to analyse it and to make decisions accordingly. Such systems areparticularly useful for video-surveillance, in which case alarms must be raised in case ofan intrusion. For cost saving and power consumption reasons, it is better to perform thatprocess as close to the sensor as possible. To address that issue, a promising approach isto use bio-inspired frameworks, which consist in applying computational biology modelsto industrial applications. The work carried out during that thesis consisted in select-ing bio-inspired feature extraction frameworks, and to optimize them with the aim t…
Détermination de la texture de la feuille de vigne par imagerie
2013
National audience; Dans le contexte de la pulvérisation de précision, nombreuses sont les recherches menées sur l'optimisation d'utilisation des produits phytosanitaires. L'objectif final étant de réduire de manière significative la quantité d'intrant dans les cultures . Dans ce cadre, les travaux présentés dans cet article s'intéresse particulièrement à l'analyse de l'état de surface foliaire qui présente une part essentielle dans le processus d'adhésion du produit pulvérisé sur la feuille. L'analyse de surface de la feuille est réalisée à travers l'analyse des caractéristiques texturale extraites d'images microscopics. Afin de discriminer les différents cépages et âges des feuilles retenu…
Vers un lien entre plasticité du cerveau et satiété
2021
Vous venez de terminer un bon repas et vous vous sentez repu ?Des chercheurs (1) viennent de comprendre des mécanismes qui, dans votre cerveau, ont contribué à cet état. Il s’agit d’une cascade de réactions déclenchée par l’élévation du taux de glucose dans le sang.Dans une nouvelle étude menée chez la souris, l’équipe dirigée par Alexandre Benani, chercheur CNRS au Centre des Sciences du Goût et de l’Alimentation (2) montre que les circuits de neurones qui freinent la prise alimentaire sont activés après un repas et cette activation implique des mouvements de cellules dans le cerveau.Cette étude a été publiée dans Cell Reports le 3 mars 2020.Lire le communiqué de presse : https://bit.ly/3j…
Impact of perturbations on the neuron response
2017
International audience; We propose an overview of the effects of deterministic and stochastic perturbations on the response of a neuron. Our study is based on numerical simulations and experiments with an elementary neural circuit. We use different excitations to highlight various phenomena such as Mode locking, Vibrational Resonance, Ghost Stochastic Resonance... We close the study with a lattice of coupled circuit.
Microglia and α-synuclein implication in Parkinson's disease
2011
Age-related neurodegenerative disorders like Parkinson’s disease take an enormous toll on individuals and on society. Despite extensive efforts, Parkinson’s disease remains incurable and only very limited treatments exist. Indeed, Parkinson’s pathogenesis is still not clear and research on its molecular mechanisms is ongoing. In this study, we focused our interest on two abnormal events occurring in Parkinson’s patients, namely α-synuclein aggregation and microglial activation. We first investigated α-synuclein and its abnormal polymerisation. For this purpose, we developed novel methods, which allowed the in vitro production of different types of α-synuclein oligomers. Using highly sensiti…
Performances of neural networks for deriving LAI estimates from existing CYCLOPES and MODIS products
2008
International audience; This paper evaluates the performances of a neural network approach to estimate LAI from CYCLOPES and MODIS nadir normalized reflectance and LAI products. A data base was generated from these products over the BELMANIP sites during the 2001-2003 period. Data were aggregated at 3 km x 3 km, resampled at 1/16 days temporal frequency and filtered to reject outliers. VEGETATION and MODIS reflectances show very consistent values in the red, near infrared and short wave infrared bands. Neural networks were trained over part of this data base for each of the 6 MODIS biome classes to retrieve both MODIS and CYCLOPES LAI products. Results show very good performances of neural …