In this way, Briggman et al. imaged the responses of ganglion cells with 2P while applying visual stimuli to an adult mouse retina. The white spots in the image to the right are the ganglion cell bodies, and the dark branches are blood vessels. The colored circles mark the locations of On-Off Direction-Selective Ganglion Cell. These direction-selective ganglion cells (DSGC) fall into four types, which are each selective to one of the four cardinal directions, and are marked by four colors (magenta, green, red, and yellow).