Retinal computations

a seminar at the Institute of Neurosciences Timone in Marseille

http://profesores.elo.utfsm.cl/~mjescobar/

Date
November 9th, 2018
Who
María José Escobar, Ph.D.
What
"Retinal computations" : The retina is part of the nervous system and consists in well-organized layers of different cell types and functions. Those cells have been vastly studied in various animal models, and also the circuits conveying to different functional categories. All these different types of either physiological properties or computation equivalents revealed the retina as not a single light to electricity encoder but a pre-processing layer, which is in charge to extract relevant visual signals from the environment that are critical for animal survival. During this seminar, we describe some of the computations performed by the retina, and how this knowledge can be applied to solve engineering problems, such as image processing and robot controllers.

Sponsored by

http://www.int.univ-amu.fr/

Probabilities and Optimal Inference to understand the Brain

IMG_20180406_164630.jpg

a 2-day workshop at the Institute of Neurosciences Timone in Marseille

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Date
April 5-6th 2018
Location

Institute of Neurosciences Timone in Marseille in the south of France

Registration

Registration was free but mandatory, participation limited to 80 persons.

Main site

https://opt-infer-brain.sciencesconf.org/

Full program

https://opt-infer-brain.sciencesconf.org/program/details.

Registration

https://opt-infer-brain.sciencesconf.org/registration is free but mandatory.

Organizing committee
Paul Apicella, Frederic Danion, Nicole Malfait, Anna Montagnini and Laurent Perrinet
Contact

opt-infer-brain@sciencesconf.org

Sponsored by

http://www.int.univ-amu.fr/

EUVIP Session 7: Biologically Inspired Computer Vision (Special Session)

Compound eyes''

description of the session

Recent advances in imaging technologies have yielded scientific data at unprecedented detail and volume, leading to the need of a shift of paradigm in image processing and computer vision. Beyond the usual classical von Neumann architecture, one strategy that is emerging in order to process and interpret this amount of data follows from the architecture of biological organisms and shows for instance computational paradigms implementing asynchronous communication with a high degree of local connectivity in sensors or brain tissues. This session aims at bringing together researchers from different fields of Biologically Inspired Computer Vision to present latest results in the field, from fundamental to more specialized topics, including visual analysis based on a computational level, hardware implementation, and the design of new more advanced vision sensors. It is expected to provide a comprehensive overview in the computer area of biologically motivated vision. On the one hand, biological organisms can provide a source of inspiration for new computationally efficient and robust vision models and on the other hand machine vision approaches can provide new insights for understanding biological visual systems. This session covers a wide range of topics from fundamental to more specialized topics, including visual analysis based on a computational level, hardware implementation, and the design of new more advanced vision sensors. In particular, we expect to provide an overview of a few representative applications and current state of the art of the research in this area.

URL

http://www-l2ti.univ-paris13.fr/euvip2016/index.php/86-euvip2016/129-tentative-technical-program-in-detail

date
October 26th, 2016
Location
Ecole Centrale Marseille
Address

38 rue Frédéric Joliot-Curie 13013 Marseille, France Phone : +33 (0)4 91 05 45 45

Programme
  • 13.30 '''Visual System Inspired Algorithm For Contours, Corner And T Junction Detection''', Antoni Buades, Rafael Grompone Von Gioi

  • 13.50 '''Biologically-inspired characterization of sparseness in natural images''', Laurent Perrinet

  • 14.10 Color filter array imitating the random nature of color arrangement in the human cone mosaic Prakhar Amba, David Alleysson

  • 14.30 '''An Illuminant-Independent Analysis Of Reflectance As Sensed By Humans, And Its Applicability To Computer Vision''', Alban Flachot, Phelma, J.Kevin O'Regan, Edoardo Provenzi

  • 14.50 '''Categorization of microscopy images using a biologically inspired edge co-occurrences descriptor''', Lionel Fillatre, Michel Barlaud, Laurent Perrinet

  • biography of organizer and contact information

    Laurent Perrinet is researcher in Computational Neuroscience at the "Institut de Neurosciences de la Timone" (France), a joint research unit (CNRS / Aix-Marseille Université). He graduated from the aeronautics engineering school SUPAERO, in Toulouse (France) with a signal processing and stochastic modelization degree. His research program is focusing in bridging the complex dynamics of realistic models of large-scale models of spiking neurons with functional models of low-level vision. His current challenge is to be able to translate, or compile in computer terminology, such functional models into neural architectures that would exhibit similar dynamics. He was co-editor of the book "Biologically inspired computer vision: fundamentals and applications", Wiley VCH, 2016. Contact Information

    FACETS Code Jam Workshop #4

    Progressive reconstruction of an image using spikes

    We held a CodeJam 22nd-24th June 2010, in Marseille.

    • From the website:

      The goal of the FACETS CodeJam workshops is to catalyze open-source, collaborative software development in computational and systems neuroscience and neuroinformatics, by bringing together researchers, students and engineers to share ideas, present their work, and write code together. The general format of the workshops is to dedicate the mornings to invited and contributed talks, leaving the afternoons free for discussions and code sprints.
      
       For the 4th FACETS CodeJam, the main theme of the meeting will be workflows: what are the best practices for combining different tools (simulators, analysis tools, visualization tools, databases etc.) to ensure the efficient and reproducible flow of data and information from experiment conception to publication and archiving?
      
       (...)
      
       The meeting organizers gratefully acknowledge the support of the European Union through the FACETS Project (grant no. IST-2005-15879), and the International Neuroinformatics Co-ordinating Facility (INCF). We also wish to express our great appreciation to the DyVA team at the Institut de Neurosciences Cognitives de la Méditerranée for providing us with a great location and much assistance.
    • http://neuralensemble.org/meetings/CodeJam4.html

    • http://neuralensemble.org/meetings/CJ4_Program_v2.pdf

    • FACETS code jam #4

    • see the presentation of an interactive neural demo.

    Computational Neuroscience: From Representations to Behavior

    Second NeuroComp Marseille Workshop

    Date
    27-28 May 2010
    Location

    Amphithéâtre Charve at the Saint-Charles' University campus - Métro : Line 1 et 2 (St Charles), a 5 minute walk from the railway station.
    Map (Amphithéâtre Charve, University Main Entrance, etc.)
    Metro, Bus and Tramway
    Getting to Marseille from Airport

    Registration

    Registration was free but mandatory, participation limited to 80 persons.

  • This workshop is organized by NeuroComp Marseille which is a local node of the NeuroComp group. First workshop was organized April 6-7 2009.

  • check out the following-up special issue rassembling some contributions to this workshop.

  • Computational Neuroscience emerges now as a major breakthrough in exploring cognitive functions. It brings together theoretical tools that elucidate fundamental mechanisms responsible for experimentally observed behaviour in the applied neurosciences. This is the second Computational Neuroscience Workshop organized by the "NeuroComp Marseille" network.

    It will focus on latest advances on the understanding of how information may be represented in neural activity (1st day) and on computational models of learning, decision-making and motor control (2nd day). The workshop will bring together leading researchers in these areas of theoretical neuroscience. The meeting will consist of invited speakers with sufficient time to discuss and share ideas and data. All conferences will be in English.

    Program

    27 May 2010 Neural representations for sensory information & the structure-function relation

    9h00-9h30

    Reception and coffee

    9h30-10h00

    Laurent Perrinet
    Institut de Neurosciences Cognitives de la Méditerranée, CNRS and Université de la Méditerranée - Marseille
    «Presentation of the Workshop and Topic»

    10h00-11h00

    Gabriel Peyré
    CNRS and Université Paris-Dauphine
    '''«Sparse Geometric Processing of Natural Images»'''
    In this talk, I will review recent works on the sparse representations of natural images. I will in particular focus on both the application of these emerging models to image processing problems, and their potential implication for the modeling of visual processing.
    Natural images exhibit a wide range of geometric regularities, such as curvilinear edges and oscillating textures. Adaptive image representations select bases from a dictionary of orthogonal or redundant frames that are parameterized by the geometry of the image. If the geometry is well estimated, the image is sparsely represented by only a few atoms in this dictionary.
    On an ingeniering level, these methods can be used to enhance the resolution of super-resolution inverse problems, and can also be used to perform texture synthesis. On a biological level, these mathematical representations share similarities with low level grouping processes that operate in areas V1 and V2 of the visual brain. We believe both processing and biological application of geometrical methods work hand in hand to design and analyze new cortical imaging methods.

    11h00-12h00

    Jean Petitot
    Centre d'Analyse et de Mathématique Sociales, Ecole des Hautes Etudes en Sciences Sociales - Paris
    «Neurogeometry of visual perception»

    In relation with experimental data, we propose a geometric model of the functional architecture of the primary visual cortex (V1) explaining contour integration. The aim is to better understand the type of geometry algorithms implemented by this functional architecture. The contact structure of the 1-jet space of the curves in the plane, with its generalization to the roto-translation group, symplectifications, and sub-Riemannian geometry, are all neurophysiologically realized by long-range horizontal connections. Virtual structures, such as illusory contours of the Kanizsa type, can then be explained by this model.

    12h00

    Lunch

    14h00-14h45

    Peggy Series
    Institute for Adaptive and Neural Computation, Edinburgh
    «Bayesian Priors in Perception and Decision Making»
    We'll present two recent projects:
    - The first project (with M. Chalk and A. R. Seitz) is an experimental investigation of the influence of expectations on the perception of simple stimuli. Using a simple task involving estimation and detection of motion random dots displays, we examined whether expectations can be developed quickly and implicitly and how they affect perception. We find that expectations lead to attractive biases such that stimuli appear as being more similar to the expected one than they really are, as well as visual hallucinations in the absence of a stimulus. We discuss our findings in terms of Bayesian Inference.
    - In the second project (with A. Kalra and Q. Huys), we explore the concepts of optimism and pessimism in decision making. Optimism is usually assessed using questionnaires, such as the LOT-R. Here, using a very simple behavioral task, we show that optimism can be described in terms of a prior on expected future rewards. We examine the correlation between the shape of this prior for individual subjects and their scores on questionnaires, as well as with other measures of personality traits.

    14h45-15h45

    Heiko Neumann(in collaboration with Florian Raudies)
    Inst. of Neural Information Processing, Ulm University Germany
    «Cortical mechanisms of transparent motion perception – a neural model»
    Transparent motion is perceived when multiple motions different in directions and/or speeds are presented in the same part of visual space. In perceptual experiments the conditions have been studied under which motion transparency occurs. An upper limit in the number of perceived transparent layers has been investigated psychophysically. Attentional signals can improve the perception of a single motion amongst several motions. While criteria for the occurrence of transparent motion have been identified only few potential neural mechanisms have been discussed so far to explain the conditions and mechanisms for segregating multiple motions.
    A neurodynamical model is presented which builds upon a previously developed neural architecture emphasizing the role of feedforward cascade processing and feedback from higher to earlier stages for selective feature enhancement and tuning. Results of computational experiments are consistent with findings from physiology and psychophysics. Finally, the model is demonstrated to cope with realistic data from computer vision benchmark databases.
    Work supported by European Union (project SEARISE), BMBF, and CELEST

    15h45-15h00

    Coffee break

    16h00-17h00

    /!\ CANCELED /!\ Rudolf Friedrich
    Institute für Theoretische Physik Westfälische Wilhelms Universität Münster
    «Windows to Complexity: Disentangling Trends and Fluctuations in Complex Systems»
    In the present talk, we discuss how to perform an analysis of experimental data of complex systems by disentangling the effects of dynamical noise (fluctuations) and deterministic dynamics (trends). We report on results obtained for various complex systems like turbulent fields, the motion of dissipative solitons in nonequilibrium systems, traffic flows, and biological data like human tremor data and brain signals. Special emphasis is put on methods to predict the occurrence of qualitative changes in systems far from equilibrium.
    [1] R. Friedrich, J. Peinke, M. Reza Rahimi Tabar: Importance of Fluctuations: Complexity in the View of stochastic Processes (in: Springer Encyclopedia on Complexity and System Science, (2009))

    17h00-17h45

    General Discussion

    28 May 2010 Computational models of learning and decision making

    9h30-10h00

    Andrea Brovelli
    Institut de Neurosciences Cognitives de la Méditerranée, CNRS and Université de la Méditerranée - Marseille
    «An introduction to Motor Learning, Decision-Making and Motor Control»

    10h00-11h00

    Emmanuel Daucé
    Mouvement & Perception, UMR 6152, Faculté des sciences du sport
    «Adapting the noise to the problem : a Policy-gradient approach of receptive fields formation»
    In machine learning, Kernel methods are give a consistent framework for applying the perceptron algorithm to non-linear problems. In reinforcement learning, the analog of the perceptron delta-rule is called the "policy-gradient" approch proposed by Williams in 1992 in the framework of stochastic neural networks. Despite its generality and straighforward applicability to continuous command problems, quite few developments of the method have been proposed since. Here we present an account of the use of a kernel transformation of the perception space for learning a motor command, in the case of eye orientation and multi-joint arm control. We show that such transformation allows the system to learn non-linear transformation, like the log-like resolution of a foveated retina, or the transformation from a cartesian perception space to a log-polar command, by shaping appropriate receptive fields from the perception to the command space. We also present a method for using multivariate correlated noise for learning high-DOF control problems, and propose some interpretations on the putative role of correlated noise for learning in biological systems.

    11h00-12h00

    Máté Lengyel
    Computational & Biological Learning Lab, Department of Engineering, University of Cambridge
    «Why remember? Episodic versus semantic memories for optimal decision making»
    Memories are only useful inasmuch as they allow us to act adaptively in the world. Previous studies on the use of memories for decision making have almost exclusively focussed on implicit rather than declarative memories, and even when they did address declarative memories they dealt only with semantic but not episodic memories. In fact, from a purely computational point of view, it seems wasteful to have memories that are episodic in nature: why should it be better to act on the basis of the recollection of single happenings (episodic memory), rather than the seemingly normative use of accumulated statistics from multiple events (semantic memory)? Using the framework of reinforcement learning, and Markov decision processes in particular, we analyze in depth the performance of episodic versus semantic memory-based control in a sequential decision task under risk and uncertainty in a class of simple environments. We show that episodic control should be useful in a range of cases characterized by complexity and inferential noise, and most particularly at the very early stages of learning, long before habitization (the use of implicit memories) has set in. We interpret data on the transfer of control from the hippocampus to the striatum in the light of this hypothesis.

    12h00-14h00

    Lunch

    14h00-15h00

    Rafal Bogacz
    Department of Computer Science, University of Bristol
    «Optimal decision making and reinforcement learning in the cortico-basal-ganglia circuit»
    During this talk I will present a computational model describing decision making process in the cortico-basal ganglia circuit. The model assumes that this circuit performs statistically optimal test that maximizes speed of decisions for any required accuracy. In the model, this circuit computes probabilities that considered alternatives are correct, according to Bayes’ theorem. This talk will show that the equation of Bayes’ theorem can be mapped onto the functional anatomy of a circuit involving the cortex, basal ganglia and thalamus. This theory provides many precise and counterintuitive experimental predictions, ranging from neurophysiology to behaviour. Some of these predictions have been already validated in existing data and others are a subject of ongoing experiments. During the talk I will also discuss the relationships between the above model and current theories of reinforcement learning in the cortico-basal-ganglia circuit.

    15h00-15h30

    Coffee break

    15h30-16h30

    Emmanuel Guigon
    Institut des Systèmes Intelligents et de Robotique, UPMC - CNRS / UMR 7222
    «Optimal feedback control as a principle for adaptive control of posture and movement»

    16h30-17h15

    General Discussion

    Sponsored by

    http://www.incm.cnrs-mrs.fr/ http://www.ism.univmed.fr/ http://sites.univ-provence.fr/ifrscc/ http://www.univmed.fr/ http://www.univ-provence.fr/ Pole 3c

    WORKSHOP: "Brain dynamics, from information to behavior"

    April 6th and 7th, 2009 @ Medecine Faculty «la Timone»

    This workshop is organized in order to promote theoretical and computational neuroscience at the future Neuroscience Institute @ la Timone.

    Monday, April 6th

    Session 1

    Modeling and Analysis of Behavior and Function Chair: Guillaume Masson

    9 :00-9 :40

    Raoul Huys: A phase flow perspective to motor control and timing mechanisms

    9 :40-10 :20

    Anna Montagnini: Dynamic inference for smooth pursuit eye movements

    10 :20-11 :00

    BREAK

    11 :00-11 :40

    Laurent Pezard: Symbolic dynamics of behavioral sequences

    11:40-12 :20

    Laurent Perrinet: Decoding low-level neural information to track visual motion

    12 :20-14 :00

    LUNCH

    Session 2

    Dynamics of neural and brain networks - Chair: Bruno Cessac

    14 :00-14 :40

    Viktor Jirsa: What does the brain do when it does nothing?

    14:40- 15 :20

    Alain Destexhe: Modeling network activity states based on conductance measurements

    15 :20-16 :00

    BREAK

    16 :00-16 :40

    Alexa Riehle: Modifications in motor cortical dynamics induced by practice

    16:40- 17 :20

    Jens Starke: Analysis of spatio-temporal pattern formation in the olfactory bulb

    Tuesday, April 7th

    Session 3

    Epilepsy - Chair: Patrick Chauvel

    9 :00-9 :40

    Christophe Bernard: Alterations in brain dynamics and behavior in epilepsy

    9 :40-10 :20

    John Terry: Applications of mean-field modelling of macroscale brain activity: Anticipation, Evolution and Suppression of Seizures

    10 :20-11 :00

    BREAK

    11 :00-11 :40

    Louis Lemieux: The study of epileptogenic networks using multimodal imaging in the resting state

    11:40-12 :20

    Fabrice Wendling: Lumped-parameter and detailed models of epileptogenic networks: insights into the interpretation of depth-EEG recordings in TLE

    12 :20-14 :00

    LUNCH

    Session 4

    Brain dynamics from brain imaging - Chair: Bruno Poucet

    14 :00-14 :40

    Stefan Kiebel: Recognizing sequences of sequences

    14:40- 15 :20

    Jean-Luc Blanc: Entropy estimation of symbolic sequences: application to synchronization detection

    15 :20-16 :00

    BREAK

    16 :00-16 :40

    Andrea Brovelli: The neural computations of instrumental learning

    16:40- 17 :20

    Petra Ritter: Spatiotemporal dynamics of spontaneous and evoked EEG-fMRI signals

    Deuxième conférence française de Neurosciences Computationnelles, "Neurocomp08"

    La deuxième conférence française de Neurosciences Computationnelles, "Neurocomp08", s'est déroulée à la Faculté de Médecine de Marseille du 8 au 11 octobre 2008. Cette conférence, organisée par le groupe de travail Neurocomp, a permis de réunir les principaux acteurs français du domaine (francophones ou non). Le champ des Neurosciences Computationnelles porte sur l'étude des mécanismes de calcul qui sont à l'origine de nos capacités cognitives. Cette approche nécessite l'intégration constructive de nombreux domaines disciplinaires, du neurone au comportement, des sciences du vivant à la modélisation numérique. Avec ce colloque, nous avons offert un lieu d'échanges afin de favoriser des collaborations interdisciplinaires entre des équipes relevant des neurosciences, des sciences de l'information, de la physique statistique, de la robotique. Cette édition a également été l'occasion d'ouvrir le cadre à de nouveaux domaines (modèles pour l'imagerie, interfaces cerveau-machine,...) notamment grâce à des ateliers thématiques (une nouveauté dans cette édition). Certains des principaux enjeux du domaine ont été présentés par quatre conférenciers invités : Ad Aertsen (Freiburg, Allemagne), Gustavo Deco (Barcelone, Espagne), Gregor Schöner (Bochum, Allemagne), Andrew B. Schwartz (Pittsburgh, USA). Des interventions orale plus courtes et plus spécifiques étaient également au programme, sur la base d'une sélection du comité de lecture. Une cinquantaine de posters ont également été présentés au cours de ces journées. Le premier jour était consacré aux modèles de la cellule neurale, aux modèles des traitements visuels et corticaux, ainsi qu'aux modèles de réseaux de neurones bio-mimétiques. La seconde journée était consacrée aux interfaces cerveau-machine, à la dynamique des grands ensembles de neurones, à la plasticité fonctionnelle et aux interfaces neurales. Enfin, la journée de samedi était consacrée à des ateliers thématiques, l'un sur les interfaces cerveau-machine, l'autre sur la vision computationnnelle. Cette conférence a connu un beau succès de par l'affluence (200 personnes environ) et la qualité des interventions. Ce succès tient également au fort soutien financier et organisationnel qu'elle a obtenu de ses partenaires. Les organisateurs remercient le CNRS, la Société des neurosciences, le conseil régional de la région Provence Alpes Côte d'Azur, le conseil général des Bouches de Rhône, la mairie de Marseille, l'université de Provence, l'IFR "Sciences du cerveau et de la cognition", l'INRIA, ainsi que la faculté de médecine de Marseille et l'université de la Méditerranée qui ont hébergé la conférence.

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