Neural processing relies on two basic elements: First, the intrinsic properties of neurons that allow processing of synaptic input from other neurons, and generation of action potentials as the computational result; second, the network of excitatory and inhibitory pathways of a complexity orders of magnitude greater than any humans have created. How these elements interact to generate computational function in the brain is the fundamental question of systems neuroscience, and we are addressing this with a symbiosis of experiments - electrophysiology and histology in the early visual system, and theoretical models – both biophysically-detailed and formal mathematical models of neurons and networks.

Thus our research focuses on how neurons and their networks accomplish functional computations, a.k.a. the biophysics of computation. The themes of this work can be divided into two general areas:

Synaptic integration and spike generation in single neurons

Each neuron in the brain instantiates a complex mapping from typically thousands of synaptic and many contextual (e.g. pancrinic) inputs, to the eventual action potential output. The biophysical structure underlying this transformation includes the non-linear interactions between synaptic inputs across neuron’s dendritic tree, the neuron’s voltage and second-messenger dependent membrane channels and, finally, the intracellular systems that regulate synaptic and membrane properties. Our work aims to characterize this mapping in neurons of the retina, hippocampus and cortex, with particular attention to the integrated analysis of the responses of neurons to both artificial (electrophysiological) and functional (visual) stimuli.

Functional architecture of cortical and peripheral brain regions

Sensory systems in the brain are characterized by the notion of the receptive field, which describes the filter properties of single cells that discriminate specific features in a given sensory modality. Our research focuses on the early visual system, including the retina, the lateral geniculate nucleus and the visual cortex, where we aim to describe the contributions of synaptic connectivity and intrinsic cellular properties that underlie classical and non-classical receptive field characteristics.

Description français (par J.J. Perrier)

Selected Publications

Team Members

• Principal Investigator - Lyle J. Graham, PhD (CNRS DR2)

• Daniele Marinazzo, PhD

• Adrien Schramm, PhD

• Iris Marangon (technician)

• Hans Bodart (intern, Université Paris Diderot)

Collaborators (alpha order)

• Anton Chizhov, PhD, Ioffe Institute, Saint Petersburg, Russia (former postdoc)

• David DiGregorio, PhD, CNRS, Institut Pasteur, Paris

• David Dubayle, PhD (MCU, Université Paris Descartes)

• Eduardo Fernandez, MD-PhD, University Miguel Hernandez, Alicante

• Boris Gutkin, PhD, CNRS, Ecole Normale Superiore Paris

• Mahmut Ozer, PhD, President (!), Zonguldak Karaelmas University, Turkey (former postdoc)

• Erez Persi, PhD, Tel-Aviv University (former postdoc)

• Johan Storm, MD-PhD, University of Oslo

• Koen Vervaeke, PhD, University College, London

Former Members

• Ricardo del Abajo, PhD (former postdoc)

• Thomas Gener, MS (former member)

• Kerry Weinberg (former intern, MIT)

• Anatoly Buchin, MS (former intern, Université Paris Descartes)

• Danyel Lee (former intern, Université Paris Descartes)

The Surf-Hippo Neuron Simulation System

Neurophysiology & New Microscopies Laboratory Université Paris Descartes, CNRS UMR 8154 45 rue des Saints Pères 75006 Paris, France

Office: +33 (0) 1 42 86 20 92 lyle@biomedicale.univ-paris5.fr