The eye’s retina, the nerve tissue lining the back of the eye, is not just a camera, but rather a camera plus a sophisticated image processing system. It receives visual information from the outside world and processes it into signals that it then sends to the brain. The processing is performed by over seventy different types of retinal neurons organized into a three-layered network. The neurons in the bottom layer, the ganglion cells, are in charge of sending signals from the eye to the brain via the optic nerve. A small subset of these cells, pictured here in different colors, specifically responds to objects that move upwards in the visual field. In this image, we are looking down on the ganglion cell layer and can see the neurons’ long projections extending away to connect to the optic nerve.
This layer of mouse retina tissue was viewed with a confocal microscope. The cells were artificially stained with different colors, depending on their positions within the layer.
Image courtesy of In-Jung Kim, PhD, and Joshua Sanes, PhD, Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University