Journal: eLife
Article Title: Aberration correction in long GRIN lens-based microendoscopes for extended field-of-view two-photon imaging in deep brain regions
doi: 10.7554/eLife.101420
Figure Lengend Snippet: ( A ) Representative x (horizontal), z (vertical) projection of a z-stack of a subresolved fluorescent layer acquired with the uncorrected (top) or corrected (bottom) microendoscope based on the 6.4 mm-long GRIN rod. λ exc =920 nm; scale bars: 50 pixels. ( B ) Thickness (mean values ± s.e.m.) of the layer as a function of the distance from the center of the FOV for uncorrected (red, n=4) or corrected (blue, n=4) microendoscopes. The thickness of the film is measured as the FWHM of the Gaussian fit of the fluorescence intensity along segments orthogonal to the tangential line to the section of the film and located at different distances from the center of the FOV (see yellow labels on the bottom image). ( C,D ) Same as ( A,B ) for the microendoscope based on the 8.8 mm-long GRIN rod. ( E ) The distortion of the FOV in uncorrected and corrected microendoscopes is evaluated using a calibration ruler. The magnification factor is defined as the ratio between the nominal and the real pixel size of the image and shown as a function of the radial distance for uncorrected (red, n=3) or corrected (blue, n=3) microendoscopes. Data are shown as mean values ± s.e.m. Fitting curves are quartic functions f(x)=ax 4 +bx 2 +c (see also for details). ( F ) Same as ( E ) for the microendoscope based on the 8.8 mm-long GRIN rod. ( G–J ) The spatial resolution of microendoscopes was measured acquiring z-stacks of subresolved fluorescent beads (bead diameter: 100 nm) located at different radial distances using 2PLSM (λ exc =920 nm). ( G ) Representative x , y and x , z projections of a fluorescent bead located at a radial distance of 75 μm, imaged through an uncorrected (left) or a corrected (right) 6.4 mm-long microendoscope. Horizontal scale bars, 2 μm; vertical scale bars, 5 μm. ( H ) Same as ( G ) for the microendoscope based on the 8.8 mm-long GRIN rod. ( I ) Axial (left) and lateral (right) resolution (i.e. average size of the x , z and x , y projections of imaged beads, respectively) as a function of the radial distance from the center of the FOV for uncorrected (red) and corrected (blue) probes. Each data point represents the mean value ± s.e.m. of n=4–24 beads imaged using at least m=3 different 6.4 mm-long microendoscopes. Fitting curves are quartic functions f(x)=ax4+bx2+c (see for details). The horizontal black dash-dotted line indicates the axial resolution threshold of 10 µm. The black triangles indicate the intersections between the threshold and the curves fitting the data and mark the estimated radius of the effective FOV of the probes. ( J ) Same as ( I ) for the microendoscopes based on the 8.8 mm-long GRIN rod. Figure 3—source data 1. Numerical values to reproduce graphs in .
Article Snippet: Other , Calibration ruler, 4-dot calibration slide , Motic , Product code: 1101002300142 , .
Techniques: Fluorescence
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