Expérimental et théorique
The study of large scale neuronal circuits throughout the brain is currently one of the biggest challenge in neurobiology. Non-invasive imaging of neuronal activity with single cell resolution is however currently limited to shallow depths, due to prominent light scattering beyond one millimeter. Photoacoustic imaging, a fascinating technique relying on ultrasound generation upon the absorption of a light pulse, has been developed to overcome this issue and probe optical absorption contrast at large depths in biological tissue. To achieve cellular resolution, the detected ultrasound bandwidth must be as large as 100 MHz, which is beyond the reach of conventional piezo-electric based sensors. The project aims at developing an all-optical photoacoustic imaging setup to non-invasively access neuronal activity at large depths (≳ 2 mm) in the mouse brain. The candidate will design and fabricate Fabry-Perot cavities for the optical interferometric detection of ultrasound. To provide high temporal resolution as required for neuronal activity imaging, the candidate will investigate wide-field interrogation strategies of these cavities. In particular, he/she will implement data acquisition and image reconstruction approaches based on compressive sensing. These techniques will be applied to perform calcium imaging in mice.