Focus-tunable microscope for imaging small neuronal processes in freely moving animals

Abstract

Miniature 1-photon microscopes have been widely used to image neuronal assemblies in the brain of freely moving animals over the last decade. However, these systems have important limitations for imaging indepth fine neuronal structures. We present a novel subcellular imaging 1-photon device that uses an electrically tunable liquid crystal lens to enable a motion-free depth scan in the search of such structures. Our miniaturized microscope is compact (10 mm x 17 mm x 12 mm), lightweight (≈ 1.4 g), provides fast acquisition rate (30-50 frames/second), high magnification (8.7x) and high resolution (1.4 μm) that allow imaging of calcium activity of fine neuronal processes in deep brain regions during a wide range of behavioural tasks of freely moving mice.