Influence de l'inhibition synaptique sur le codage de l'information par les cellules mitrales du bulbe olfactif

Maxime Ambard 1
1 CORTEX - Neuromimetic intelligence
INRIA Lorraine, LORIA - Laboratoire Lorrain de Recherche en Informatique et ses Applications
Abstract : This thesis studies the encoding of sensory information in olfactory bulb relay neurons by combining experimental data analysis with computer modelling. The olfactory bulb is mainly composed of excitatory cells, called mitral cells, interconnected via local inhibitory neurons, called granule cells.

In the first part of the thesis, the analysis of electrophysiological data, recorded in vitro from rat olfactory bulb slices, shows that mitral cell firing is phase-locked to the fast local field potential oscillation. This phase-locking is largely reduced when the inhibitory synaptic conductance is pharmacologically blocked, hence highlighting the important role of synaptic inhibition. In order to extract the time course of the inhibitory synaptic conductance, we propose a new method based on the adjustment of a neuron model from experiments with local injections of a synaptic blocker. Using this method, we find that the inhibitory conductance fluctuations are correlated to the local field potential oscillations. A relationship between the received inhibition and the phase of mitral action potentials is also revealed. The probability to fire a phase-locked action potential increases if the neuron receives a large number of inhibitory synaptic events, and if these events are themselves phase-locked.

In the second part of the thesis, results from the previous analysis are used to design a computational model of the olfactory bulb in order to explore the encoding capacity of the mitral-granule interplay. It appears likely that mitral cells encode information in precise spike timings rather than in firing rates. We therefore study analytically the influence of the number and the temporal dispersion of the received inhibitory synaptic events on the spike timing precision of mitral cells. Our study concludes that spike timing precision requires a strong synaptic coupling between mitral and granule cells. Lastly, our olfactory bulb model is applied to the recognition of odours by using an array of artificial gas sensors.
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https://tel.archives-ouvertes.fr/tel-00401813
Contributor : Maxime Ambard <>
Submitted on : Monday, July 6, 2009 - 10:43:59 AM
Last modification on : Monday, April 16, 2018 - 10:42:05 AM
Long-term archiving on: Tuesday, June 15, 2010 - 6:04:29 PM

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  • HAL Id : tel-00401813, version 1

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Maxime Ambard. Influence de l'inhibition synaptique sur le codage de l'information par les cellules mitrales du bulbe olfactif. Modélisation et simulation. Université Henri Poincaré - Nancy I, 2009. Français. ⟨tel-00401813⟩

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