Applied mathematics and computational neuroscience - Paris

Mathematical techniques for extracting synaptic activity from intracellular measurements
in neurons.

The objective of this project is to develop, analyze and implement mathematical methods
for extracting information about the synaptic conductances from neurophysiological
recordings. To achieve this objective we propose to address the following three
questions.
1) Measuring conductances in central neurons in vivo is essential to understand the
response selectivity of those neurons. Response selectivity can arise from particular
timings of excitation and inhibition, which can be amplified by intrinsic conductances.
In intracellular experiments, one can measure the membrane potential V(t), but the
conductances are hidden variables. We are interested in extracting the excitatory
synaptic conductance ge(t) and the inhibitory conductance gi(t), which are related to
V(t) through a differential equation. Because two variables are to be deduced from a
single quantity, all previous methods are based on multiple trials, which necessarily
mean that information about the variability unlocked to the stimulus is lost. We have
started to develop a method for single-trial measurements, which uses a controlled noisy
current injected in the neuron and a minimization procedure.
2) Another aspect of the project is the recording technique itself. Currently, our
recordings use a novel technique called Active Electrode Compensation, which uses an
electrode model and a computer program running in real time to control the recording
electrode. There are several aspects of this technique which would need improvements and
extensions.
3) Finally, we are also interested in extracting spike-triggered averages from
intracellular recordings.

We are collaborating on this project with Alain Destexhe and Yves Frégnac at the UNIC
lab (CNRS Gif-sur-Yvette), where all experiments (both in vitro and in vivo) will be
performed. The postdoctoral fellow will test his algorithms on experimental data but is
not expected to participate actively in the experiments. Details of the project are
available there:
<http://www.di.ens.fr/~brette/HRCORTEX/>http://www.di.ens.fr/~brette/HRCORTEX/

We are looking for a postdoctoral fellow with expertise in applied maths or physics, and
experience in programming. The research work will be related to the following domains:
control theory, signal processing, dynamical systems, probabilities, optimization.
Knowledge of neurophysiological models is a plus but is not required. A clear interest
for interdisciplinary work is an obvious requirement.

The candidate will work for 2 years in the Odyssee Lab at the Computer Science
Department of Ecole Normale Supérieure in Paris (45, rue d’Ulm, very central, in the
heart of the Quartier Latin) and/or at INRIA Sophia-Antipolis, near Nice on the French
Riviera. The position is fully funded by an ANR Neuroscience project.

Candidates should send a CV and the address of two referees to Romain Brette
(<mailto:Romain.Brette@ens.fr&gt;Romain.Brette@ens.fr) and Olivier Faugeras
(<mailto:Olivier.Faugeras@sophia.inria.fr&gt;Olivier.Faugeras@sophia.inria.fr). For further
information please contact Romain Brette.