In short, we are sending lasers into mouse brains to create sound so that we can measure the electrical activity of neurons.
We are developing advanced optical techniques to image non-invasively the electrical activity of single neurons in mice at large depths (> 1 mm). In this regime, much of the light has been scattered multiple times by the brain tissue and therefore cannot be used to build high resolution images (even with 2 or 3-photon microscopy). So we add another kind of waves to help us out: ultrasounds. When absorbers (like hemoglobin, or calcium indicators) heat up under pulsed illumination, they emit pressure waves that are not scattered by soft tissue, and can therefore be externally measured to reconstruct the inner optical absorption: this is the principle of photoacoustic imaging. But the conventional piezoelectric detectors are not sensitive enough at high frequencies needed to resolve single neurons. So we add one more laser, in order to optically measure sound and reach the desired resolution.
We believe that this new technique can have a significant impact in neurobiology, by providing non-invasive access to the deeper layers of the cortex and to the hippocampus.
Hi! I'm Thomas Chaigne and I'm working on this project as CNRS research fellow since January 2019.
Between 2012 and 2016, I did my PhD with Sylvain Gigan and Emmanuel Bossy at Langevin Institute and Kastler-Brossel Lab, where I combined wavefront shaping and photoacoustic imaging in order to focus light inside scattering media, and investigated super resolution in photoacoustic imaging.
Mosaic is an interdisciplinary research group gathering physicists and biologists interested in various topics such as nanophotonics, advanced optical imaging, tissue morphogenesis and neuroscience.
11 PIs and more than 30 postdocs and PhD students are part of this international group.
The Fresnel Institute is a research unit supported by Aix-Marseille Université, CNRS and Ecole Centrale Marseille. Bringing together over 170 scientists around various topics (electromagnetism, metamaterials, nanophotonics, optical
components, data processing, advanced imaging), the Institute is one of the largest optics/imaging-oriented lab in France.
We are always looking for curious and motivated candidates with interest ranging from physics to neurobiology, with a taste for making what you can't buy and deciphering what you don't understand.
Feel free to drop me an email using the link below.