Figure 1: Fast volumetric Ca2+-imaging across a cortical column in the in-vivo mouse. a Cartoon depicting the extend of a cortical column as well as its cortical layers. Red line indicates maximum depth during imaging. b Left: 3D rendering of imaged volume (500x500x500µm), individual neurons are clearly resolved. Right: Example Ca2+ signal (∆F/F0) of GCaMP6 fluorescence extracted from the data. Time traces of 16 neurons out of a total of ~4000 are shown. Volume acquisition rate is 3Hz.
Figure 2: Brillouin microscopy. a Schematic layout of our confocal Brillouin microscope, in which two highly dispersive devices (‘VIPAs’) spatially disperse the scattered light spectrum onto a camera, from which visco-elastic properties of the sample can be deduced. b Brillouin microscopy stiffness map of a live zebrafish tail. Larger frequency shifts denote ‘stiffer’ tissue parts. In collaboration with the Diz-Muñoz lab.
The Prevedel group develops new optical techniques for investigating dynamic cellular processes deep inside tissue in-vivo.
Light microscopy has revolutionized our understanding in many areas of biology, and over the years tremendous progress has been achieved by imaging cellular and subcellular processes in transparent, fixed, or thin sample preparations. Yet in order to obtain a complete understanding of biological processes, in-vivo studies inside thick, three-dimensional living tissues are often required. However, when light interacts with thick biological tissue, the process of light scattering leads to low-resolution, ‘blurry’ images and an effective loss of excitation power with increasing imaging depth. This has severely limited the biomedical usefulness of light microscopy to, e.g., cultured cells in vitro or superficial layers of tissue in vivo. New approaches and tools are thus required to noninvasively image biological function at depth inside living tissue with sufficient resolution, speed and contrast.
Previous and current research
In the past, we have developed novel optical techniques for high-speed imaging, with a particular focus on functional imaging in the neurosciences. Amongst others, we have put forward a two-photon microscopy technique based on light-sculpting that has enabled the first whole-brain calcium imaging in C. elegans. In other work, we have established light-field deconvolution microscopy, an elegant approach to perform volumetric imaging that achieves unprecedented acquisition speeds while requiring no mechanical scanning. Recently, we extended our imaging methods to the scattering tissue domain and demonstrated fast volumetric calcium imaging across the majority of a cortical column in the mouse. Together with our collaborators, we apply our methods to study neuronal activity and cellular dynamics in a range of model organisms such as zebrafish larvae or behaving mice (see Fig. 1). Another focus of the group is to develop new optical techniques based on Brillouin scattering to ‘image’ mechanical properties of living tissues in a non-contact fashion and with diffraction-limited resolution in 3D (see Fig. 2).
Future projects and goals
The future focus of the group is to push the frontiers of deep tissue microscopy in terms of imaging depths and resolution by developing advanced and innovative optical imaging techniques. To do so we actively work in diverse fields such as multi-photon microscopy, active wave-front shaping, photo-acoustics as well as Brillouin spectroscopy. In particular, we intend to combine these into multi-modal imaging systems that allow studying cellular processes and dynamics at depths inaccessible so far by conventional microscopy. Our multidisciplinary team comprises of physicists, engineers, computer scientists and biologists, and we engage in close collaboration with fellow groups at EMBL in the fields of cell and developmental biology as well as neuroscience.