Imaging Through the Whole Brain of Drosophila at λ/20 Super-Resolution

Abstract

Recently, many super-resolution technologies were demonstrated, significantly impacting biological studies by observation of cellular structures down to nanometer precision. However, current super-resolution techniques mostly rely on wavefront engineering or wide-field imaging of signal blinking/fluctuation, and thus imaging depth are limited due to tissue scattering/aberration. Here we present a technique that is capable to image through an intact Drosophila brain with 20 nm lateral resolution at ~200 μm depth. The spatial resolution is provided by molecular localization of a photoconvertible fluorescent protein Kaede, whose blinking state is reported for the first time. The deep-tissue observation is enabled by optical sectioning of spinning disk microscopy, as well as reduced scattering of optical clearing. Together these techniques are readily available for many biologists, providing three-dimensionally resolution of densely entangled dendritic fibers in a complete Drosophila brain. The method paves the way toward whole-brain neural network studies, and is applicable to other high-resolution bio-imaging.

Keywords: deep-tissue imaging, neural circuit tracing, photoconvertible fluorescent protein, localization microscopy