Séminaire ICE : « Nonlinear optical microscopy of developing and brain tissue »

Abstract
Many questions in developmental biology and neuroscience require tissue-scale measurements of multiple cell parameters. Recent progress in in-depth and large-scale microscopy approaches are transforming brain imaging, but generally lack efficient color contrast modalities. After introducing the basic concepts of multiphoton microscopy, the talk will discuss ongoing work aiming at augmenting the information content of multiphoton microscopy of tissues.
First, we will present chromatic multiphoton serial (ChroMS) microscopy, a recent approach combining trichromatic two-photon (2P) excitation through wavelength mixing and microtome-based serial block-face image acquisition to acquire large-volume images of color-labelled brain tissue. This approach provides micrometric color imaging with constant resolution over the entire imaged volume. We illustrate its potential of ChroMS for several types of measurements, such as color-based morphological, clonal and connectivity analyses. Then, we will discuss three-photon (3P) microscopy, a recent approach providing superior imaging depth than 2P microscopy in highly scattering tissues, but requiring the development of novel infrared MHz OPA sources. Finally, we will discuss the combination of multiphoton fluorescence imaging with coherent contrast modalities providing complementary information such as third harmonic generation (THG).

Bio
Emmanuel Beaurepaire (EB) is a specialist of multiphoton microscopy of biological tissues. Trained in engineering physics and informatics in INP Grenoble (France), he worked two years as a visiting scientist at Cornell University (NY,USA) in Prof Watt Webb’s lab, and prepared a PhD in optics at ESPCI in Paris (France) with Claude Boccara and Jerome Mertz. He was hired by the CNRS in 2001 and joined the laboratory for optics and biosciences at Ecole polytechnique (Palaiseau,France), where he initiated and coordinates the advanced microscopy group. EB pioneered many technological fields such as third-harmonic generation microscopy and multicolor 2-photon microscopy, and their applications to live embryo imaging and neurodevelopment.