Date : 05/05/2011

Internship proposal for : Master 2

Laboratory
IBENS UMR CNRS 8197 et INSERM 1024
46 rue d'Ulm
75005 Paris
Website: http://www.biologie.ens.fr/neuroctx/
Main discipline: Neurophysiology
Lab Director : Antoine Triller

Mentor
Laurent Bourdieu
E-mail: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
Phone: 0144323734

Subjects
subject 1: myelin
subject 2: optical microscopy
subject 3: cortex

Summary of lab's interests

Recently, the development of new experimental approaches allowing for simultaneous recording of many individual neurons in the living animal has lead to increasing interest in the dynamical coordination between the activities of cells in neural network. It is expected that the precise temporal organization of brain activity, such as the synchrony of discharge of hundreds or thousands of individual neurons, could be closely related to the coding and storing mechanisms used to represent information in the central nervous system. The work in our group participates to the study of this spatio-temporal organization of brain activity, and aims at a better understanding of the rules that governs encoding processes. Experimental approaches on behaving rats include multi-electrode recordings and, on anaesthetized rats, intra-cellular recordings and fast two-photon microscopy.

Summary of project

The degeneration of the neuron myelin sheath is involved in many neuropathologies of the central and peripheral nervous system. Quantitative myelin imaging is a necessary tool to follow the demyelination process and to evaluate potential remyelinating treatments. Unfortunately, current imaging techniques cannot provide images of individual myelinated fibers forming a sparse network in the grey matter. However, demyelination of the grey matter is an important hallmark of neurodegenerative diseases.
We have recently design a new optical method referred as deep-OCM, which allows the non-invasive observation of individual un-labeled myelinated fiber in the cortex of anaesthetized rats. This technique is based on optical coherence tomography (OCT), which consists in an interferometric selection of back-scattered photons in a thin slice within the thick tissue. Deep-OCM is an adaptation of OCT to the imaging in the depth (hundreds of microns) and at high spatial resolution (less than a micron in 3D) of biological tissue.
We have recently equipped our two-photon microscope with a deep-OCM setup. The project will have two parts:
- The characterization of the image formation in deep-OCM as a function of the depth penetration in the tissue, and in comparison with two-photon images. An adaptive optic loop will be used to improve image quality, which is degraded by optical aberration due to the tissue.
- The quantitative measurement of the evolution of the myelinated fiber concentration in the cortex of anaesthetized mice, in a model of neurodegenerative disease induce by cuprizone .