Structure and function of the olfactory bulb microcircuit

Michele Pignatelli
EPFL, 2009
EPFL thesis

Abstract

The aim of this study is to contribute to understand the physiology of the Olfactory System through detailed microcircuit investigation, adopting advanced electrophysiological and anatomical techniques. Multiple patch clamp recordings allow understanding the structural foundations supporting the network architecture, the biophysical rules adopted by the microcircuit connectivity and the fine dynamic of the synaptic transmission. The study focuses on the Olfactory Bulb microcircuit as a first neuronal processor of sensory inputs. The excitatory elements of the Olfactory Bulb microcircuit are anatomically defined by affiliation to the same receptive field: the Glomerulus. A correlated subthreshold activity between microcircuit elements defines the physiological signature of the microcircuit. We experimentally addressed three fundamental issues: origin of the correlated subthreshold activity, connectivity rules and dynamic of the synaptic transmission. In the first study we attribute the origin of correlated subthreshold activity to a class of pacemaker cells responsible for the synchronization of the population onset and acting therefore as a timer of the microcircuit response. In the second study we investigated the connectivity rules supporting the interaction between excitatory cells. The tight apposition between gap junctions and chemical synapses on the excitatory cells dendrites allows gap junctions to propagate postsynaptic potentials toward surrounding compartments. The result of the propagation is represented by an enhancement in the amplification of the sensory information and an increase in the speed of the reaction time. In the third study we extensively analyzed the mechanisms of the synaptic transmission and the activity dependent properties of synapses, revealing a potential role for the short-term plasticity in the development of the sensory processing. The results of our investigation are going to constitute the foundation of a database available for high definition multi-compartmental modeling of the Olfactory Bulb network.

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https://infoscience.epfl.ch/record/129756?ln=en

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Michele Pignatelli
EPFL, 2009
EPFL thesis

Abstract

Official source

https://infoscience.epfl.ch/record/129756?ln=en

About this result

Related concepts (22)

Related concepts

Related publications (46)

Related publications

Related publications (46)

Coding of temporal information by activity-dependent synapses

Henry Markram, Idan Segev

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2002

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Michele Giugliano

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2010

Transmission across neocortical synapses depends on the frequency of presynaptic activity (Thomson & Deuchars, 1994). Interpyramidal synapses in layer V exhibit fast depression of synaptic transmission, while other types of synapses exhibit facilitation of transmission. To study the role of dynamic synapses in network computation, we propose a unified phenomenological model that allows computation of the postsynaptic current generated by both types of synapses when driven by an arbitrary pattern of action potential (AP) activity in a presynaptic population. Using this formalism, we analyze different regimes of synaptic transmission and demonstrate that dynamic synapses transmit different aspects of the presynaptic activity depending on the average presynaptic frequency. The model also allows for derivation of mean-field equations, which govern the activity of large, interconnected networks. We show that the dynamics of synaptic transmission results in complex sets of regular and irregular regimes of network activity.

1998