Tamily Weissman, Jeff Lichtman, and Joshua Sanes (2007). Image taken from a transgenic “Brainbow” mouse that enables neuroscientists to distinguish between neighboring, densely packed neurons by illuminating them in different colors. This photomicrograph shows a few of the many neurons that are found in the neocortex.
Image via "Portraits of the Mind: Visualizing the Brain from Antiquity to the 21st Century," by Carl Schoonover; Published by Abrams, featured on Book Bench, the New Yorker blog
Made me think of the kaleidoscope that is Klimt: