MiniFAST: A sensitive and fast miniaturized microscope forin vivoneural recording

Abstract

Observing the activity of large populations of neurons in vivo is critical for understanding brain function and dysfunction. The use of fluorescent genetically-encoded calcium indicators (GECIs) in conjunction with miniaturized microscopes is an exciting emerging toolset for recording neural activity in unrestrained animals. Despite their potential, current miniaturized microscope designs are limited by using image sensors with low frame rates, sensitivity, and resolution. Beyond GECIs, there are many neuroscience applications which would benefit from the use of other emerging neural indicators, such as fluorescent genetically-encoded voltage indicators (GEVIs) that have faster temporal resolution to match neuron spiking, yet, require imaging at high speeds to properly sample the activity-dependent signals. We integrated an advanced CMOS image sensor into a popular open-source miniaturized microscope platform. MiniFAST is a fast and sensitive miniaturized microscope capable of 1080p video, 1.5 μm resolution, frame rates up to 500 Hz and high gain ability (up to 70 dB) to image in extremely low light conditions. We report results of high speed 500 Hz in vitro imaging of a GEVI and ~300 Hz in vivo imaging of transgenic Thy1-GCaMP6f mice. Finally, we show the potential for a reduction in photobleaching by using high gain imaging with ultra-low excitation light power (0.05 mW) at 60 Hz frame rates while still resolving Ca2+ spiking activity. Our results extend miniaturized microscope capabilities in high-speed imaging, high sensitivity and increased resolution opening the door for the open-source community to use fast and dim neural indicators.

EDoF-Miniscope: pupil engineering for extended depth-of-field imaging in a fluorescence miniscope

“…We will also utilize a backside illuminated (BSI) CMOS sensor to significantly improve the SNR and dynamic range for in-vivo studies. While cutting edge sensors may increase the size and weight of the miniscope 11 , we are encouraged by the recent development of the MiniFAST BSI CMOS-based miniscope 31 in successfully applying high data rate and high pixel count BSI sensors to future generations of the EDoF-Miniscope. Our studies indicate that we may further decrease the size and weight of the platform while nominally affecting its imaging properties to further reduce the formfactor (see Supp.1.2 ) .…”

Wide-Field Calcium Imaging of Neuronal Network Dynamics In Vivo

“…Future iterations of such mini-mScopes could potentially include faster image sensors [ 160 ] to perform voltage imaging across the cortex in mice expressing GEVIs specifically optimized for mesoscale single-photon imaging [ 140 ]. Such devices may reveal new insights into how mesoscale activity at temporal scales higher than those that can be captured using Ca 2+ imaging mediate complex behaviors.…”

Large depth-of-field ultra-compact microscope by progressive optimization and deep learning

“…Thereby, not only compressing over 100,000 times in volume, our integrated microscope obtains the imaging performance beyond a commercial 5× microscope with over 10-times improved DOF which is necessary for practical applications on rough surfaces of most samples across a large FOV. Even compared with existing advanced miniaturized microsopes 25,[34][35][36][37][38] , the proposed integrated microscope has a much smaller size and weight (Supplementary Table 1). In the meantime, the total cost of the system is below 10 dollars for mass production with the plastic lenses used and no cemented lenses involved.…”