Viren Jain, a postdoc in Seung's MIT lab, with the help of researchers at the Max Planck Institute for Medical Research in Heidelberg, Germany, mapped the neurons in a rabbit's retina. Each color represents a distinct neuron. The neurons were traced from a large set of monochrome pictures of the rabbit's retina taken with an electron microscope, such as the black-and-white images on either side of the neural tangle.