摘要：SummaryTo understand brain functions, it is important to observe directly how multiple neural circuits are performing in living brains. However, due to tissue opaqueness, observable depth and spatiotemporal resolution are severely degradedin vivo. Here, we propose an optical brain clearing method forin vivofluorescence microscopy, termed MAGICAL (magical additive glycerol improves clear alive luminance). MAGICAL enabled two-photon microscopy to capture vivid images with fast speed, at cortical layer V and hippocampal CA1in vivo. Moreover, MAGICAL promoted conventional confocal microscopy to visualize finer neuronal structures including synaptic boutons and spines in unprecedented deep regions, without intensive illumination leading to phototoxic effects. Fluorescence emission spectrum transmissive analysis showed that MAGICAL improvedin vivotransmittance of shorter wavelength light, which is vulnerable to optical scattering, thus unsuited forin vivomicroscopy. These results suggest that MAGICAL would transparentize living brains via scattering reduction.Graphical AbstractDisplay OmittedHighlights•Oral glycerol administration (MAGICAL) enhances fluorescent signals in living brains•MAGICAL achievesin vivooptical clearing for living brains via scattering reduction•MAGICAL enablesin vivomicroscopy to observe brains faster, deeper, and more finelyOptical Imaging; Neuroscience
