Cortical dynamics and coding mechanisms

Leader

Research center

45 rue d’Ulm
75230 Paris
Marc Mézard

Institution

Ecole Normale Supérieure
Inserm
CNRS
ED158
Université Pierre et Marie Curie

Laboratory

Institut de Biologie de l'ENS IBENS
U1024 UMR8197
Labex Memolife, Programme France Bio-Imaging, NIH Brain Initiative 2017

Keywords

Integrative neuroscience
Tactile sensory modality
Barrel cortex
Two-photon fluorescence microscopy
Adaptive optics
Available to host a PhD student

Publications

L. Estebanez, J. Bertherat, D.E. Shulz, L. Bourdieu, J.-F. Léger, High order statistics of naturalistic stimuli are orderly mapped in the primary somatosensory cortex, (2016) Nature Comm. 7:13528.

J. Wang, J.-F. Leger, J. Binding, C. Boccara, S. Gigan and L. Bourdieu, Measuring aberrations in the rat brain by coherence-gated wavefront sensing using a Linnik interferometer, Biomed. Opt. Exp. (2012) 3(10) 2510-25.

V. Szabo*, C. Ventalon*, V. De Sars, J. Bradley, and V. Emiliani, “Spatially selective photoactivation with computer generated holography and functional fluorescence imaging in freely behaving mice with a fiberscope”, Neuron, 84 (6), 1157-1169. (2014) * Equal contribution.

S. Schott, J. Bertolotti, J.F. Léger, L. Bourdieu and S. Gigan, Characterization of the angular memory effect of scattered light in biological tissues. Opt. Exp. 23(10) (2015) 13505-16, arXiv:1502.00270.

W. Akemann, J.-F. Léger, C. Ventalon, B. Mathieu, S. Dieudonné and L. Bourdieu, Fast spatial beam shaping by acousto-optic diffraction for 3D non-linear microscopy, Opt. Express 23(22), 28191-28205 (2015).

 

Fields of research

Neurophysiology / systems neuroscience

Research Theme

We study the representation of sensory information in a cortical column by recording optically the activity of tens to thousands of neurons. We are interested in particular in the tactile information collected by the rodent whiskers and encoded in the barrel field of the primary somato-sensory cortex. Our work focuses on the coding of elementary stimuli at the scale of a single whisker and on the influence on this integration of the sensory context, which can be modulated e.g. by the spatio-temporal correlation of all whiskers.

To address these questions, our group develops new experimental tools that allow in two-photon fluorescence microscopy the optimal recording of neuronal network activity in vivo on anaesthetized or behaving animals: adaptive optics to improve imaging depth, ultrafast scans using acousto-optic deflectors to increase the temporal resolution of the recordings as well as their signal to noise ratio, and optical coherent tomography to visualize myelinated axons without labeling.

Team members

Wang Jinyu
Paresys Gérard
Léger Jean François
Ventalon Cathie

Lab rotation

Adaptive changes in neuronal receptive fields during different conditioning strategies

Team leader: 

BOURDIEU Laurent

Dates: 

January 2, 2018 - June 29, 2018

Application deadline: 

June 29, 2018

Period

~ Jan-March 2018

~ April-June 2018 (to be discussed)

Project

We propose to study how cortical receptive fields  in the primary auditory cortex (A1) can be rapidly reshaped by behavioral conditioning. We will use multi-electrodes (Silicon probes) to record neuronal activity in anaesthetized and in awake mice. We will focus on adaptive plasticity in receptive fields of A1 neurons, and explore how operant conditioning for a single tone can change the receptive field properties of both inhibitory interneurons and excitatory pyramidal cells, and how this process depends on cortical layers.

Experiments will consist in (i) implanting electrodes over the auditory cortex of naive mice, (ii) measuring neuronal receptive fields in a large ensemble of neurons, (iii) training animals on an auditory task, (iv) measuring changes in the receptive fields of the same cells following conditioning. An important aspect of these experiments is that we will use two different reinforcement strategies during training – one group of mice will receive aversive (negative reinforcement) conditioning and a second group of mice will receive appetitive (positive reinforcement) conditioning. This will allow us to analyze the effects of reward valence, as well as tone conditioning, on neuronal receptive field plasticity. In parallel, a PhD student in the team is currently studying the effect of conditioning in the upper layers of A1 (layers I-III) with two-photon microscopy calcium imaging. The comparison of the observed changes in supragranular, granular and subgranular layers of A1 will provide a complete view of the circuit rearrangements taking place in this cortex during learning. This is a collaborative project between our group and Dr. Shihab Shamma’s group at the DEC department (ENS). The supervision of this project will be done by Jean-François Léger in Laurent Bourdieu’s team at IBENS and Yves Boubenec in Shihab Shamma’s team at the DEC. These experiments will provide a better understanding of the cellular basis of adaptive neuronal changes during classical conditioning, and also yield new insights into the effects of learning and reward on early sensory processing.

Contact

Ecole Normale Supérieure - IBENS - 46, rue d’Ulm 75005 Paris - +33 1 44 32 37 34 - leger@biologie.ens.fr

Supervisor: 

LEGER Jean-François