A Computational Framework for Ultrastructural Mapping of Neural Circuitry
A typical low magnification (3,000×) field for synaptic screening in the rabbit inner plexiform layer was captured on a Hitachi H-600 with film images at ≈25% overlap. (A and B) represent part of the overlapping fields with slightly different densities due to the auto-exposure of different images.
(C and D) represent the difference of (A and B) after translational/rotational best alignments for two regions (circles 1 and 2). When imagery in circle 2 is aligned best (C) the regions in circle 1 are shifted and have a higher image dispersion. The same is true when imagery in circle 1 is aligned best (D). The quality of alignment is quantified by normalized intensity histograms of corresponding patches. When spots are well-aligned (blue) the histograms are narrow, when poorly aligned (yellow) the intensity variance is high. The two spots are 6 μm apart. The histograms are peak normalized pixel number (ordinate) versus pixel value (abscissa, 0–255). Arrows indicate various ribbon and conventional synapses.